*Golbaghi, G. (1); Haghdoost, M. (1); Pitard, I. (1); Castonguay, A. (1)

(1) INRS - Institut national de la recherche scientifique

Ruthenium complexes are presently an object of great attention in the field of medicinal chemistry, as antitumor agents with selective antimetastatic properties and low systemic toxicity. Interest in Ru anticancer drugs has been growing rapidly since NAMI-A and KP1019 have successfully entered phase II clinical trials. Besides, some ruthenium complexes are active against platinum resistant cells and also display less side effects. Our goal is to create a series of multitasking ruthenium complexes bearing aromatase inhibitors currently used for estrogen receptor positive breast cancer (ER+) therapy. Ruthenium can act as a cell-killing agent through various modes of action, whereas aromatase inhibitors such as Letrozole and Anastrozole can act as anticancer agents by linking to aromatase, blocking the activity of the enzyme responsible for the production of estrogens in postmenopausal women. In this presentation, we report the synthesis of a series of ruthenium-Letrozole and ruthenium-Anastrozole complexes as well as their characterization using various techniques, including nuclear magnetic resonance spectroscopy, X-ray crystallography and high resolution mass spectrometry. In addition, we report their in vitro human breast cancer cell antiproliferative and antimigratory activities, which were assessed by MTS and wound healing assays, respectively. Furthermore, the results of in vivo toxicity test of the complexes on zebrafish embryos are also discussed.

*Haghdoost, M. (1); Golbaghi, G. (1); Létourneau, M. (1); Castonguay, A. (1)

(1) INRS - Institut national de la recherche scientifique

Ruthenium complexes are promising candidates to replace platinum-based drugs, as they tend to exhibit high activity against cis-platin resistant cell lines and induce a lower occurrence of side effects than platinum-based complexes, possibly due to their different mechanism of actions [1]. In this study, four new structurally similar Ru(II) complexes with bidentate N,O donor ligands are reported, including the synthesis, characterization and in vitro antiproliferative activity of two different human cancer cell lines, notably MCF-7 (breast) and SH-SY5Y (neuroblastoma). Their structural properties, aquation reactivity, lipophilicity and cellular uptake as well as their ability to catalyze the reduction of NAD+ to NADH under abiotic and biological conditions were also studied. Results showed that the cytotoxicity, cellular uptake and lipophilicity of these complexes are significantly related to each other. The established lipophilicity-cytotoxicity relationship was used to design a ruthenium complex with a much higher antiproliferative activity.

[1] Leijen, S., et al., Invest New Drugs, 2015. 33(1): p. 201-14.

*Schott, O. (1); Chartrand, D. (1); Pal, A. K. (1); Hanan, G. S. (1)

(1) Département de Chimie, Université de Montréal, Montréal, Québec, H3C 3J7

The development and well-being of our society rely on innovative research concerning sufficient clean energy resources. Nowadays, with global warming issue, new alternatives to fossil fuels are based on carbon neutral energies. In the field of molecular artificial photosynthesis, photo-catalytic systems are developed to oxidize water in order to reduce CO₂ or protons [1]. Mimetic system for hydrogen generation was initiated by Lehn and Al. [2]: a system with a sacrificial electron donor such as triethanolamine, a photosensitizer Ru(bipy)₃²⁺ and ' cobaloxime ' catalyst produce some hydrogen under blue light irradiation. Efficiency of photo-systems PS/Cat linked by coordination bonding is explored in literature [3]. Recently in our group, development of polynuclear supramolecular architecture Ru/Co proves greater efficiency as compared to Ru(bipy)₃²⁺[4]. In this following work, a heteroleptic photosensitizer [Ru(L)X(bipy)₃-X]²⁺ (L= 4,4'-Bis(phenyl)aminocarbonyl] -2,2'-bipyridine) are investigated in different photo-reaction conditions (various wavelengths of irradiation, various concentrations, organic or aqueous media). In this case, a other supramolecular approach by halide recognition of amide pocket and the chloride of cobaloxime are evaluated for photo-catalysis. Additionally, cyclohexyl oxime Co derivative catalysts are experimented for hydrogen generation. Ru[(diphenyl-[4,4'-Bis(phenyl)aminocarbonyl]-2,2'-bipyridine)(bipy)₂][PF₆]₂ and Co(chg)₂ClDMAP(chg=cyclohexane1-2dione oxime) enhance interesting performances compared to references. Herein, photo-physical, electrochemical measurements, and photo-catalytic activities of the new species are discussed.

[1] Serena Berardi, Samuel Drouet, Laia Franca`s, Carolina Gimbert-Surinach, Miguel Guttentag, Craig Richmond, Thibaut Stoll , Antoni Llobet. Chem.Soc. Rev. 2013, 42, 1847
[2] J. Hawecker, J-M Lehn, R. Ziessel, Nouveau Journal de Chimie. 1983, 7, 271
[3] Frischmann, P. D.; Mahata, K.; Wuerthner, F. Chem. Soc. Rev. 2014, 43, 7501
[4] Rousset, E.; Chartrand, D.; Ciofini, I.; Marvaud, V.; Hanan, G. S. Chem Commun (Camb) 2015

*Harkness, R. (1); Mittermaier, A. (1)

(1) McGill University

G-quadruplexes (GQs) are 4-stranded DNA structures formed by tracts of stacked, Hoogsteen-hydrogen bonded guanosines. GQs are found in gene promoters and telomeres where they regulate gene transcription and telomere elongation. Though GQ structures are well-characterized, many aspects of their conformational dynamics are poorly understood. For example, when there are surplus guanosines in some of the tracts, they can slide with respect to one another, a process we term G-register (GR) exchange. These motions could in principle entropically stabilize the folded state, crucially benefitting GQs as their stabilities are closely tied to biological function. We have developed a method for characterizing GR exchange where each isomer in the wild-type conformational ensemble is trapped by mutation and thermal denaturation data for the set of trapped mutants and wild-type are analyzed simultaneously. This yields GR isomer populations as a function of temperature, quantifies conformational entropy and sheds light on correlated sliding motions of the G-tracts. We measured entropic stabilizations from GR exchange up to 14.3 ± 1.6 J mol^-1 K^-1, with melting temperature increases up to 7.3 ± 1.6°C. Furthermore, bioinformatic analysis suggests a majority of putative human GQ sequences are capable of GR exchange, pointing to the generality of this phenomenon.

*Labelle, M.-A. (1); Ispas-Szabo, P. (1); Mateescu, M.-A.(1)

(1) Département de chimie, Université du Québec à Montréal

En Europe, les Maladies Inflammatoires Chroniques de l’Intestin (MICI) augmentent tous les ans avec plus de 260 000 nouveaux cas. L’objectif de cette étude est d’obtenir des comprimés de sulfate de baryum (BS) avec différentes charges et d’observer leur comportement comme traceurs pour les MICIs. Hypothèse : certains polymères pourraient générer des matrices avec un temps de livraison prédéterminée pour différents segments du tractus gastro-intestinal et permettre d’imager avec précision les boyaux. Différents polymères (cationique, anionique, neutre) ont été étudiés en relation avec la charge de BS (10-80% w/w). Les comprimés obtenus par compaction directe ont été analysés par la dureté ainsi que leur comportement pendant l’hydratation par des fluides gastriques et intestinaux simulés. Les polymères anioniques CarboxyMéthyl Cellulose et CarboxyMéthyl Amidon peuvent contenir jusqu’à 60% de BS et sont donc indiqués pour la livraison au petit intestin. HydroxyPropylMéthyl Cellulose (HPMC, un polymère neutre) a démontré une grande stabilité à haute charge (80%) et est recommandé comme transporteur pour l’acheminement au colon.

*Luo, Z. (1); Friscic, T. (1); Khaliullin, R. (1)

(1) McGill University

Despite very similar structure pregnenolone (pre) and progesterone (pro), two steroid molecules, demonstrate dramatically different propensity to interact with aromatic molecules. It has been recently found that in the solid-state complexation with a wide variety of aromatic systems, pro forms cocrystals unselectively with almost all of them whereas pre cocrystallizes only with very few. The importance of intermolecular interactions of steroids for their biological signaling function motivated us to perform a systematic comparative analysis of intermolecular binding in cocrystals of pro and pre. To make such comparative examination possible we designed a computational procedure that generates experimentally inaccessible structures of pre cocrystals without relying on conventional crystal structure prediction algorithms, which would be unfeasible in this case. A detailed examination of the fundamental nature of interactions between steroid and aromatic molecules revealed that the different cocrystallization propensity of pro and pre cannot be attributed to the difference in the distribution of charges over the steroid backbone as has been suggested before. The observed phenomenon has more complex origins than previously thought and is a result of a fine balance between the strength of steroid-steroid and steroid-aromatics interactions.

*Palato, S. (1); Seiler, H. (1); McGovern, L. (2); Kambhampati, P. (1)

(1) Department of Chemistry, McGill University, Montreal, Canada
(2) Département de Chimie, École Normale Supérieure, Paris, France

Les nanocristaux ultrapetits (<1.1m) de séléniure de cadmium (NC CdSe) présentent un pic de photoluminescence (PL) large, au rouge de la photoluminescence de l’exciton de cœur. Le contrôle de cet état de surface permettrait des applications dans le domaine de l’éclairage et de la nano-détection[1]. Or, la compréhension microscopique de cet état de surface est incomplète. Nous rapportons les résultats de l’analyse de la PL des NC ultrapetits grâce à un spectromètre streak, dotée de résolution simultanée en temps et longueur d’ondes. La photoluminescence résolue en temps révèle un pic de surface dynamique, se déplaçant vers le rouge (jusqu’à 100nm en 500ns). Ce phénomène, jusqu’ici inconnu, est présent pour toutes les tailles de NC ultrapetits étudiés et est influencé par les ligands. L’échelle temporelle lente et la magnitude de ce décalage spectral n’est pas prise en compte par les modèles actuels de l’émission blanche de ces matériaux. L’échelle de temps similaire au temps de vie de la fluorescence suggère l’occurrence de plusieurs populations indépendantes, aux spectres et dynamiques différentes. Les données peuvent être expliquées par un faible nombre de telles populations (2-3). Cette explication est cohérente avec des études récentes sur l’impact des ligands sur la PL de surface[2].

[1] L. Jethi, M. M. Krause, and P. Kambhampati, J. Phys. Chem. Lett. 6, 718 (2015).
[2] M. M. Krause and P. Kambhampati, Phys. Chem. Chem. Phys. 17, 18882 (2015).

*Rojas-Gutiérrez, P. A. (1); DeWolf, C. (1); Capobianco, J. (1)

(1) Concordia University

Lanthanide doped nanomaterials have gained significant attention due to the fact they can emit light under a multiphoton excitation process, where they are able to convert low energy light such as near-infrared (NIR) to ultraviolet and visible emissions in a process known as upconversion. Lanthanide-doped upconverting nanoparticles (Ln-UCNPs) have garnered attention for developments of novel biological probes. However, several requirements such as, water dispersibility, bio-compatibility, high colloidal stability, and the possibility of functionalization with targeting agents, must be achieved before Ln-UCNPs reach their full potential in biological applications. Supported lipid bilayer (SLB) is a self-assembling of two-dimensional continuous bilayer made of lipid molecules that interact via hydrophobic interactions, mimicking cell membranes. Enveloping nanoparticles with SLB is an alternative method that produces water dispersible nanoparticles with high bio-compatibility and gives the possibility of drug encapsulation inside the lipid bilayer. In the present work we show the formation and characterization of a SLB on LiYF₄:Tm³⁺/Yb³⁺ UCNPs.

Reber, C. (1); *Schütz, M. (2)

(1) Université de Montréal
(2) Technische Universität München

Since 1998, at least 15 theoretical studies presenting calculations on the vibrational frequencies of cis- and trans-Pt ( [PtCl₂(NH₃)₂] ) have been published. However, only a few of them include experimental results, especially for trans-Pt. This work presents detailed variable-temperature Raman spectra of cis- and trans-[PtCl₂(NH₃)₂], as well as of cis-[PtBr₂(NH₃)₂]. Important recent information about temperature dependent structural changes in the cis-Pt system[1] is expanded towards trans-Pt and cis-[PtBr₂(NH₃)₂], two compounds for which only low-quality or no crystal structures are reported, despite their current pharmaceutical interest.[2] Our experimental data form a new benchmark for theoretical studies.[3] The influence of isotope distribution, crystal packing and asymmetry effects on vibrational band splitting is outlined. For cis-[PtBr₂(NH₃)₂], the Raman spectra and crystal structures expand fundamental physical information about this rather neglected compound.[4]

[1] V. P. Ting, M. Schmidtmann, C. C. Wilson, M. T. Weller, Angewandte Chemie International Edition 2010, 49, 9408-9411.
[2] T. Marzo, G. Bartoli, C. Gabbiani, G. Pescitelli, M. Severi, S. Pillozzi, E. Michelucci, B. Fiorini, A. Arcangeli, A. G. Quiroga, BioMetals 2016, 1-8.
[3] Y. Wang, Q. Liu, L. Qiu, T. Wang, H. Yuan, J. Lin, S. Luo, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2015, 150, 902-908.
[4] K. Nakamoto, P. J. McCarthy, J. Fujita, R. A. Condrate, G. T. Behnke, Inorganic Chemistry 1965, 4, 36-43.

*Khan, A. (1); Borozenko, O. (2); Badia, A. (2); DeWolf, C. (1)

(1) Department of Chemistry, Concordia University, 7141 Sherbrooke Street West, Montréal, Québec
(2) Département de Chimie, Université de Montréal, 2900 boulevard Edouard-Monpetit, Montréal, Québec

As oxygen is inhaled it has to first cross a very thin layered membrane, lung surfactant, before it can enter the bloodstream. This lung surfactant membrane is composed of saturated and unsaturated phospholipids and membrane proteins which serve to reduce the surface tension at the air-liquid interface of the alveoli preventing alveolar collapse. To maintain this function through repetitive compression-expansion cycles, the film employs a mechanism of reversible reservoir formation and exhibits a high degree of fluidity. The inhalation of nanoparticulate may interfere with the functional properties of pulmonary surfactant including lowering the film collapse, altering viscoelastic properties and modifying lipid reservoir formation. This study aims to determine the degree to which nanoparticles interfere with the phase structure, compressibility, and viscoelastic properties when they deposit on the lipid membrane. The lung surfactant films are modelled using monolayers of lipid-only mixtures and natural membrane extracts, namely Survanta and Infasurf (two clinical formulations comprising extracted lipids and proteins in different ratios). Surface pressure area-isotherms, Brewster angle microscopy, rheological measurements and GIXD data of films in the absence and presence of cationic, neutral and anionic silica nanoparticles will be presented.

*Miclette Lamarche, R. (1); DeWolf, C. E. (1)

(1) Concordia university

Phenolic compounds such as tannins exhibit antioxidant, metal chelating and protein-binding abilities; surfactants with this functionality may confer these properties to self-assembled structures and surfaces. We have previously shown the phenolic headgroup to be extremely self-adhesive give strong lateral rigidity to monolayers at liquid surfaces. The extent to which the phase behaviour can be tuned by modifying the intermolecular interactions via changes in subphase composition (such as pH, salt concentration and temperature) will be presented for lauryl gallate (C12) and octadecylgallate (C18) surfactants which exhibit liquid expanded and condensed phases, respectively, at the air water interface. The film organizational changes are determined by grazing incidence x-ray diffraction (GIXD) while morphology is assessed using Brewster angle microscopy at the air-water interface and atomic force microscopy for films deposited on mica. The competition of hydrogen-bonding and p-stacking interactions between headgroups can be manipulated to yield highly directional domain growth and control over the inter-surfactant distance. Contrary to what is observed for most surfactant monolayers, GIXD measurements show that the gallate headgroups are arranged in a crystalline packing state with limited free rotation, attributed to strong hydrogen bonding and p-stacking interactions of the gallate headgroup. The combination of parameters required to modify this preferred headgroup arrangement will be discussed. An understanding of the impact of these parameters on film organization is essential for the design of functional surface coatings.

*Allouche, E. M. D. (1); Charette, A. B. (1)

(1) Université de Montréal

The cyclopropane moiety is the 10th most used ring for the development of new drugs.[1] For this reason, our research group is developing methodologies for the synthesis of stereoenriched cyclopropanes. Recently, the enantio- and diastereo- synthesis of highly substituted iodocyclopropanes have been described.[2] In order to access highly 1,2,3-substituted stereoenriched cyclopropanes moieties, new coupling conditions of iodocyclopropanes were developed. Although the Suzuki-Miyaura cross-coupling of iodocyclopropanes had been reported in the 1990's,[3] a complete optimization to improve the yields and the scope of the reaction was undertaken to make this transformation a very useful process to generate more complex cyclopropane derivatives.

[1] Taylor, R. D.; MacCoss, M.; Lawson, A. D. G. J. Med. Chem. 2014, 57, 5845.
[2] (a) Beaulieu, L.-P. B.; Zimmer, L. E.; Charette, A. B. Chem. Eur. J. 2009, 15, 11829. (b) Beaulieu, L.-P. B.; Zimmer, L. E.; Gagnon, A.; Charette, A. B. Chem. Eur. J. 2012, 18, 14784.
[3] Charette, A.B.; Giroux, A. J. Org. Chem. 1996, 61, 8718-8719.

*Alshamrani, A. K. (1); Jessop, P. G. (1)

(1) Queen's University

Neutral organic bases such as amidines are very useful in studies of the reactivity of CS₂ to create C-C bonds. Reaction of amidines with CS₂ in the absence of water and without adding other reagents or solvents is less documented. In this study, the examined cyclic amidines have shown different reactivity, and produced different important sulfur and nitrogen containing products. Previously, in our lab the reaction of CS₂ with acyclic amidines with no NH bond and having both bulky and non bulky groups to the imine nitrogen tend to form isothiocyanates and thioamide simultaneously without addition of solvent or desulfurization reagents. In contrast, in the recent study, the reaction of cyclic amidines tetrahydropyrimidines with CS₂ required adding solvent to complete the reaction, and they form different products (amidinium salt, zwitterionic adduct, or cyclic trithioanhydride) depending on the substituents on the amine nitrogen or central carbon of the amidine. The difference in the reactivity is attributed to the ability of the acyclic amidine molecules to rotate around the imine (N=C) bond after it bind to the CS₂ to produce two linear molecules, while that cannot happen in the case of the cyclic amidines.

*Chen, F. (1); Forgione, P. (1)

(1) Concordia University

Palladium catalyzed C-C bond formation method is an important part in synthetic chemistry. Pd-mediated desulfinative cross-coupling reactions is one of the recently developed environmental benign cross-coupling reactions. The starting material sulfinate salts are bench stable and easy to handle, but can undergo self-disproportionation in solution. Therefore, it is limiting the use of this useful method in synthesis. Extending the versatility of the usage of sulfinate salts can be achieved through the introduction of a protecting group to maintain the sulfinic acid functional group. The pyridine functional group is chosen mainly due to the directing impact on the ortho-functionalization and it can also act as a protecting group. The Pd-catalyzed halogenation with pyridine directed ortho-functionalization provide access to other useful scaffolds. Later the N-heteroarenes can be removed to regain the sulfinic acid functional group for further transformation. All those approaches can contribute to the methods in accessing multi functionalized arene systems.

*Chingle, R. (1); Lubell, W. D. (1)

(1) Université de Montréal, Department of Chemistry, Succursal Centre-ville, Montréal, Quebec, H3C 3J7, Canada

Azopeptides have been synthesized for the first time by oxidation of aza-glycine residues and their pericyclic chemistry explored in the pursuit of peptidomimetics [1,2]. Diels-Alder cyclization and Alder-ene reactions on the imino urea amino amide surrogates have enabled respectively construction of constrained aza-pipecolyl residues and assembly of aza-allylglycines possessing substituents on the α- and β-nitrogen of the semicarbazide. Azopeptide configuration and influence on conformation were studied by X-ray crystallography. Azopeptide intermediates were used to synthesize mimics of the Ala-Val-Pro-Ile sequence from the second mitochondria derived activator of caspases (Smac) protein [2]. Evaluation for ability to induce apoptosis in cancer cells in MCF-7 breast cancer cells identified novel azapeptides that induced cell death more ef?ciently than the parent tetra-peptide likely by a caspase-9 mediated apoptotic pathway.

[1] Chingle, R.; Lubell, W. D. Org. Lett. 2015, 17, 5400-5403
[2] Chingle, R.; Ratni, S.; Claing, A.; Lubell, W. D. Biopolymers (Pept. Sci.) 2016, 106, 235-244

*Crifar, C. (1); Lubell W. D. (1)

(1) Université de Montréal

Peut-être l'un des plus importants motifs rencontrés dans les produits naturels, les indoles sont aussi communément employés en chimie des matériaux. En médecine, ils sont même référés comme des "pharmacophores privilégiés". Ce dernier siècle, une attention toute particulière a été portée sur la synthèse et la fonctionnalisation d’indoles et dérivés. La synthèse des indoles substitués en position 3 par un groupement alkyle est d’autant plus importante par leur utilité et leurs propriétés physiologiques. La chimie en flux continu a rarement été appliquée à la synthèse d’indoles. Plus précisément, seule la synthèse de Fisher a été reportée. Nous décrirons une méthode alternative, en flux continu, développée afin d’obtenir des indoles substitués en position 3.

*Geranurimi, A. (1); Lubell, W. D. (1)

(1) University of Montreal

Les analogues de α-amino-β-hydroxy-γ-lactames (Hgl) peuvent être considérés comme des analogues rigides de sérine ou de thréonine. En effet, les angles dièdres ω, ψ, et χ ainsi que les tours β peuvent être stabilisés par le cycle lactamique. Les stéréo-isomères des α-amino-β-hydroxy-γ-lactames (Hgl) ainsi que leurs homologues α-amino-γ-lactames (Agl) ont été synthétisés et incorporés dans une séquence peptidique d’intérêt afin d’étudier l’influence de la configuration sur la conformation et l’activité biologique. Une étude par spectroscopie de dichroïsme circulaire a été employée afin d’évaluer la capacité des différents diastéréomères à adopter une conformation de tour β et la comparer avec leurs activités biologiques, et ainsi pouvoir déterminer la conformation active. De plus, par modification du groupement hydroxyle, une seconde génération de β-substitué α-amino-γ-lactames ont été préparé afin de mimer d’autres chaines latérales d’acides aminés.

de léséleuc, M.§ (1); *Godin, É.§ (1); Parisien-Collette, S. (1); Lévesque, A. (1); Collins, S. K. (1)

(1) Université de Montréal

Les macrolactones sont l’un des motifs les plus répandus en chimie, mais leur synthèse est souvent difficile à cause de la compétition avec la réaction intermoléculaire lors de l’étape de macrocyclisation. Les stratégies traditionnelles pour contourner le problème d’oligomérisation requièrent l’utilisation de conditions d’addition lente et de haute dilution. Notre groupe a développé des conditions de couplage de type Glaser-Hay d’alcynes terminaux macrocycliques en utilisant la stratégie de séparation de phase. Cette technique nous permet d’effectuer la macrocyclisation à haute concentration sans la nécessité d’addition lente. Les travaux présentés portent sur l’application de cette méthode pour la synthèse d’un macrocycle complexe. La synthèse totale formelle de l’Ivorenolide A, une macrolactone à 18 membres qui possède un motif diyne conjugué et des propriétés immunosupprésantes, sera discutée. Les étapes-clés inclus une macrocyclisation de type Glaser-Hay en débit continu et une réaction de métathèse d’oléfine Z-sélective.

Minozzi, C. (1)

(1) Université de Montréal

La catalyse photochimique utilisant la lumière visible devient une technique de plus en plus utilisée dans le développement de la chimie. C’est une technique puissante permettant de réaliser de nombreuses réactions chimiques dans des conditions douces et offrant une grande chimiosélective dans la formation de liens carbone carbone. De nombreux photocatalyseurs sont utilisés pour réaliser ces transformations, notamment comme les catalyseurs de Ruthénium ou Iridium qui ont une très bonne réactivité mais leur rareté présente un désavantage. Je présente ici le développement et l’application de nouveaux catalyseurs de cuivre hétéroleptiques comportant des ligands phosphines et amines bidentate. Due à leur large gamme d’absorbance ces photocatalyseurs sont capables de performer dans des processus réactionnels différents comme un couplage réducteur décarboxylatif C(sp)3-C(sp), les réactions de transfert d’atome ou encore la conversion d’alcools en halogènes.

Raymond, M. (1); *Morin, É. (1); Dubart, A. (1); Collins, S. K. (1)

(1) Université de Montréal

La neomarchantin A est un produit naturel, membre de la famille des composés bisbibenzyliques, qui est extrait de la plante chinoise Marchantia polymorpha. La synthèse de ces composés emploie habituellement une macrocyclisation difficile nécessitant souvent un grand excès de réactifs, une haute dilution et/ou l’addition lente du substrat. Notre groupe s’intéresse depuis longtemps à l’amélioration des réactions de macrocyclisation. Nous présenterons une synthèse de la neomarchantin A comportant, comme étape-clé, une réaction catalytique de fermeture de cycle par métathèse réalisée dans un réacteur gaz-liquide en débit continu.

*Plescia, J. (1); De Cesco, S. (1); Mariaule, G. (1); Moitessier, N. (1)

(1) McGill University

Le cancer est une maladie qui affecte 40% des canadiens. Plusieurs liens ont été découverts concernant la croissance des tumeurs. Au sein de notre groupe de recherche, nous nous concentrons sur deux protéases à sérine: prolyl oligopeptidase (POP) et la protéine d'activation du fibroblaste (FAP) qui sont liées à l'angiogenèse et la croissance des tumeurs, respectivement. Nous utilisons notre propre logiciel de modélisation pour découvrir des composés prometteurs comme inhibiteurs covalents. Nous avons effectué des séries de criblages virtuels pour chacune de nos enzymes : notre premier objectif était de développer des inhibiteurs sélectifs de POP. Après avoir modifié virtuellement des composés prometteurs, nous avons synthétisé avec beaucoup de succès trois série de molécules peptidomimétiques et bicycliques très actives et sélectives in vitro et dans les cellules. Avec le succès de ce projet, nous l'avons étendu pour trouver des inhibiteurs doubles de FAP-POP. Nous avons synthétisé récemment une série d'inhibiteurs potentiels peptidomimétiques en seulement deux étapes. Présentement, nous avons étendu encore plus le projet pour concevoir un acide boronique bicyclique chiral, le premier de son genre, dont la synthèse actuellement est en cours (< 10 étapes).

*Rochette, E. (1); Fontaine, F.-G. (1)

(1) Université Laval

Les paires de Lewis frustrées (FLPs) sont reconnues pour leur capacité à activer une diversité de petites molécules, notamment l’hydrogène moléculaire, ce qui a mené à leur application dans plusieurs systèmes catalytiques sans métal. Récemment, la réactivité des FLPs a été étendue à l’activation de liens Csp²-H ainsi qu’à la borylation catalytique d’hétéroarènes. Les récentes avancées concernant la synthèse et l’activité de précatalyseurs stables aux conditions ambiantes ainsi que le design et la synthèse de catalyseurs plus actifs seront discutées.

*Santandrea, J. (1); Minozzi, C. (1); Cruché, C. (1); Collins, S. K. (1)

(1) Université de Montréal

Alkynes are among the most versatile and derivatized functional groups in organic synthesis. They can be directly substituted by a heteroatom (N, O, P, S), but heteroatom-substituted alkynes have yet to be fully exploited in synthesis. The limited use of these compounds is mostly due to the underdeveloped methods to access them. In recent years, however, copper-catalyzed procedures have been developed to construct nitrogen-substituted alkynes (ynamines and ynamides), which have shown considerable utility in modern synthesis. In contrast, less progress has been made toward the formation of sulfur-substituted alkynes, despite the prominence of sulfur-carbone bonds in biomolecules and drugs. Herein, we report the development of a photoredox-mediated continuous-flow synthesis of alkynyl sulfides that employs an organic fluorophore and nickel(II) catalyst system. Highly chemoselective C-S coupling of aryl bromoalkynes with thiols can be achieved under mild reaction conditions. The rapid continuous-flow process displays excellent functional group tolerance, as well as high reproducibility from small to large scale synthesis.

*Tac, F. (1); Mangel, D. (1); Babity, S. (1); Lalonde, S. (1); Forgione, P. (1)

(1) Concordia University

Heteroaromatic compounds have been shown to play a significant role in several disciplines such as material chemistry, agrochemical and pharmaceutical industry. Hence, there has been a great emphasis on development of methodologies for the synthesis of such motifs. Although effective, classical synthetic routes involve the use of harsh reaction conditions and dangerous organometallic compounds. More recently, the attention has been turned towards the development of more efficient novel methodologies employing milder reaction conditions and environmentally safe compounds. Herein we describe synthetic routes to form heteroaromatic motifs in a simple yet efficient manner through the use of diaryliodonium salts as coupling partners in decarboxylative and desulfinative palladium-catalyzed cross-coupling reactions.

*Atmuri, N. D. P. (1); Lubell, W. D. (1)

(1) Université de Montréal

Azabicyclo[X.Y.0]alkanone amino acids serve as constrained peptide mimics and scaffolds for combinatorial chemistry. A general synthetic strategy has been achieved giving access to a set of these fused ring systems: 5,5-, 5,6-, 6,5-, 6,4-, 6,6-, and 7,5. Iodo-azabicyclo[X.Y.0]alkanone amino acid derivatives were prepared by employing electrophilic transannular cyclization of 8-, 9- and 10-membered unsaturated macrocyclic lactams. The latter were prepared by coupling of various ω-unsaturated amino acids followed by ring closing metathesis on the resulting dipeptides. Enantiomerically pure ω-unsaturated amino acid building blocks were made by transition metal catalyzed cross-couplings starting from iodo-alanine. Dihedral angles from X-ray crystallographic analyses of the 8-, 9- and 10-membered macrocycle lactams and several bicyclic amino acids reveals their potential to mimic the central residues of ideal β-turn geometry.

*Boutin, H. (1); Rochette, É.(1); Bouchard, N. (1), Légaré Lavergne, J. (1), Matta C.F. (2) and Fontaine, F.G. (1)

(1) Université Laval
(2) Mount Saint Vincent University

Les paires de Lewis frustrées (FLPs) se montrent efficaces pour l’activation de plusieurs molécules non réactives et pour la catalyse des réactions d’hydrogénation, d’hydroboration et d’hydrosilylation de substrats insaturés. La coopération entre la base de Lewis (L) et l’acide de Lewis (Z) permet le clivage de substrats (R-H), menant à la formation des ions [L-H]⁺ et [Z-R]^-. Ces transformations reposent sur le changement d’oxydation de la base de Lewis (azote ou phosphore) de +3 à +5. L’acide de Lewis (Bore) est cependant plus réfractaire au changement de degré d’oxydation. À partir du ansa-aminohydroborane (1-NMe₂-2-BH₂-C₆H₄), notre groupe a réussi à réduire spontanément le bore en libérant une molécule d’hydrogène, et former une liaison B-B. Les diboranes avec liaisons B-B se sont montrés utiles pour les réactions de borylation catalysé par des métaux de transitions. La possibilité d’accéder au degré d’oxydation +2 du bore pourrait ouvrir la porte à plusieurs transformations d’oxydoréduction par les FLPs.

*Mohammadpour, F. (1); Hou, X. (2); Chemtob, S. (2); Lubell, W. D. (1)

(1) Département de Chimie, Université de Montréal
(2) Département de Pédiatrie, Université de Montréal

New labor-inhibiting drugs (so-called tocolytics) are needed to effectively suppress premature labour and prolong pregnancy. The prostaglandin F2a (PGF2a) receptor (FP) plays a key role in uterine contractions during term and preterm birth. Azapeptides possess a semicarbazide that acts as an amino amide surrogate. Aza-amino acyl proline analogues were found to modulate FP and inhibit PGF2a-induced uterine contractions by a mechanism involving biased G protein-coupled receptor signaling. We will present a structure-activity relationship study of such azapeptide FP modulators that is being pursued to understand their mechanism of action, to gain insight into the influence of different signaling pathways on labour, and ideally, to provide improved means for delaying preterm birth.

*Ricard, S. (1); Gagnon, A. (1); Daoust, B. (2)

(1) Université du Québec à Montréal
(2) Université du Québec à Trois-Rivières

Les couplages catalysés au cuivre entre des composés azotés et des diiodures vinyliques ont été très peu étudiés et seuls quelques exemples intramoléculaires sont rapportés.[1] L’intérêt d’utiliser des diiodures vinyliques comme partenaires de couplage est d’avoir accès à des iodures vinyliques β-azotés qui peuvent ensuite procéder à un second couplage. Le groupe du Pr. Daoust a développé une méthode efficace pour la préparation d’acides aminés non naturels à partir d’amides par fonctionnalisations C–N et C–O successives du trans-diiodoéthène suivies d’un réarrangement de Claisen.[2] Dans ce projet, nous voulons optimiser la méthode pour pouvoir coupler des carbamates à des diiodures vinyliques non symétriques, puis à différents alcools allyliques pour former des allylvinyléthers fonctionnalisés. Ces derniers, sous l’action de la chaleur, pourraient procéder à un réarrangement de Claisen et former des cétones α-aminés-γ,δ-insaturées. Dans cette présentation, nous discuterons de l’optimisation de la méthode, de son application à différents substrats et de la polyvalence des iodures vinyliques β-azotés.

[1] Jiang, B.; Tian, H.; Huang, Z.-G.; Xu, M. Organic Letters, 2008, 10, 2737.
[2] a) Sanapo, G. F.; Daoust, B. Tetrahedron Letters., 2008, 49, 4196. b) Ricard, S.; Sanapo, G. F.; Rahem, N.; Daoust, B. Journal of Organic Chemistry, 2016, 81, 5066.

Navuluri, C. (1); *Siddiqui, S. H. (1); Charette, A. B. (1)

(1) Université de Montréal

Cyclopropanes are ubiquitous in Nature and are widely used in pharmaceutically and agrochemically relevant compounds. The enantioselective cyclopropanation of allylic alcohols using the bifunctional chiral controller, dioxaborolane, affords the corresponding cyclopropylmethanol derivatives in high yields and enantioselectivities. This transformation has been extensively used in the synthesis of natural products and active pharmaceutical ingredients. Upon completion the cyclopropanation reaction necessitates a strongly oxidative or a highly basic work up to liberate the boron-ligated cyclopropylmethanol derivatives limiting access to base-sensitive functionalities. Thus, a modified non-oxidative work-up allows for functional group compatibility and affords base-sensitive cyclopropylmethanol derivatives. The developed method is applicable for the related halocyclopropanation reactions mediated by the chiral dioxaborolane ligand.

*Hadj-Moussa, H. (1); Storey, K. B. (1)

(1) Carleton University

When faced with harsh sub-zero winters, the wood frog (Rana sylvatica) retreats into a state of suspended animation by freezing up to 65% of its total body water in extracellular ice masses, displaying no measurable brain activity, respiration, or heartbeat. Freeze tolerance is a metabolically depressed state characterized by the global suppression of cellular functions and a reprioritization of energy usage. This complex balance of gene activation and suppression is controlled in part by the expression of microRNAs (short, non-coding RNA transcripts). MicroRNAs are proving to be master regulators of virtually all biological processes and act to selectively inhibit protein translation. This study aimed to elucidate the mechanisms by which microRNAs orchestrate natural vertebrate freeze tolerance. Immunoblotting was used to characterize microRNA biogenesis proteins in brains of control (5°C), frozen (24h at -3°C), and thawed (8h at 5°C) wood frogs, with results showing the differential regulation of key proteins over the freeze-thaw cycle. A modified stem-loop qPCR technique was used to characterize the relative expression levels of 120 wood frog specific microRNAs. Bioinformatics target enrichment predicted that the freeze-responsive microRNAs targeted genes involved in cellular processes vital for coordinating brain cryoprotection, such as axon guidance, endocytosis, and the circadian rhythm.

*Khan, I. A. (1,2); Yoo, B. H. (1,2); Masson, O. (1,2); Baron, S. (3); Corkery, D. (2,4); Dellaire, G. (2,4); Attardi, L. D. (3); Rosen, K. V. (1,2)

(1) Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
(2) Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
(3) Department of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, CA, USA
(4) Department of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada

The ability of breast cancer cells to resist anoikis, apoptosis caused by detachment of non-malignant epithelial cells from extracellular matrix (ECM), is thought to be critical for breast tumor growth, invasion and metastasis. ErbB2, an oncoprotein is often overproduced in breast tumors and blocks breast cancer cell anoikis via mechanisms that are partially understood. We found that detachment of non-malignant human breast epithelial cells from ECM upregulates a pro-apoptotic protein Perp in these cells. Perp is a component of desmosomes and can cause apoptosis via unknown mechanisms. We established that ErbB2 overexpression in detached breast epithelial cells downregulates Perp in a Mek-dependent manner. We found that activation of Mek, increases cellular levels of Sprouty-2 which promotes further accumulation of epidermal growth factor receptor (EGFR) in breast cancer cells. EGFR then triggers Perp loss by these cells. We further demonstrated that Perp downregulation rescues detached non-malignant breast epithelial cells from death. Moreover, we observed that introduction of exogenous Perp in ErbB2-overproducing breast cancer cells kills them. In summary, we identified a novel mechanism that allows breast cancer cells to grow in a three dimensional manner. This mechanism is mediated by ErbB2-dependent loss of Perp by breast cancer cells.

*Logan, S. (1) and Storey, K.B. (1)

(1) Department of Biology, Carleton University

Winter is accompanied by environmental stressors which prompt a variety of animals to hibernate to survive. By hibernating, ground squirrels can save ~90% of the energy that they would otherwise expend over the winter if they kept a high core body temperature. Metabolic suppression involves the careful management of energy stores such that only certain genes are expressed to maintain cell viability and whole body homeostasis. Formerly thought to be activated upon mild cold-stress alone, cold-shock proteins like CIRP, HuR, and Rbm3 are now known to also respond to stressors such as UV/IR irradiation, chemical imbalances, heat shock, hypoxia, and starvation. These proteins have roles in mRNA stabilization and transport, as well as in the control of mRNA translation via their binding to translation machinery. The present study characterizes the response of CIRP, HuR and Rbm3 to hibernation in the muscle and liver of 13-lined ground squirrels. Relative protein/phosphorylation levels of CIRP, HuR, Rbm3 and known binding partners (eIF4E, p-4EBP, eIF2-alpha, etc.) were quantified via immunoblotting, as was RNA-binding protein cytoplasmic-nuclear distribution. Q-PCR was used to measure the levels of downstream transcripts (Ptbp1, Nr1d2). The present study suggests that RNA-binding proteins have an important role in the response to torpor.

*Rousseau, O (1); Ebert, M. C. C. J. C. (1); Pottel, J. (1); Moitessier, N. (1); Pelletier,J. N. (1)

(1) Université de Montréal

The enzyme P450 BM3 (BM3) is part of the large family of P450s able to catalyze the challenging regiospecific oxidation of non-activated carbon atoms in a single step, a reaction of great industrial importance. Mutations within the enzyme can modulate the oxidation reaction towards new substrates through round of mutagenesis. For this purpose, I mutated BM3’s active site at 49 positions based on rational design and screened the libraries using an easy colorimetric plate assay based on the oxidation of indole to indigo. The plate screening revealed 29 new positions able to produce indigo and a gradation of blue in the colonies indicated the efficiency of each variants. Therefore the variants were pooled in 3 categories: white, light blue and dark blue and were sent to next-generation sequencing for rapid, cheap and massive identification. To further characterize the variants, an automated high-throughput method was optimized based on the fluorescence of the consumed NADPH co-factor. On 56 individual variants from V78, A82, F87, A264 and T268, already multiple mutations such as A82E, A82Q, A82K, V78S and V78A were found to have a high indigo conversion rate similar to the previously characterized mutations A82W and A82F. In a second round of screening, these methods will be used for novel conversions of industrial importance.

*Babu, J. (1); Khan, F. (1); Rosonina, E. (1)

(1) York University

Sumoylation (the covalent attachment of the SUMO peptide to cellular proteins) is a post-translational modification affecting diverse proteins in eukaryotic cells. However, proteins involved in transcription are one of the largest groups of sumoylation targets, and we find that the vast majority of SUMO targets are found on chromatin. Specifically, sumoylated proteins are associated with promoters of transcriptionally active genes in yeast, implying a general role for sumoylation during gene induction. To understand what role promoter-bound factor sumoylation plays in regulating gene expression, we applied a novel technique called ‘anchor away.’ By this method, the sole SUMO conjugating enzyme, Ubc9, is conditionally translocated to the cytoplasm, thereby blocking all nuclear sumoylation events. Under some conditions, depleted nuclear sumoylation resulted in a consistent increase in the expression of various constitutive genes, pointing a general transcription repressive role for the modification. However, this effect was not seen when the yeast cells were synchronized at the G1 phase with α-factor treatment. Although it was hypothesized that SUMO plays a critical role in regulating the gene induction process, our results indicate that promoter associated sumoylation might function to restrict gene expression only during certain stages of the cell cycle.

*Girard, M. (1, 2); Guité-Vinet, F. (1, 2); Montpas, N. (1, 2); Heveker, N. (1, 2)

(1) University of Montreal
(2) CHU Sainte-Justine

CXCR3 is the chemokine receptor responsible for T cell trafficking towards inflamed or injured tissues. CXCR3 induces T cells chemotaxis by detecting increasing gradients of the inflammatory chemokines Mig, IP-10 and ITAC. Chemokine gradients must be regulated to mediate an appropriate immune response. A mechanism that appears to be important for this is chemokine degradation. Chemokine degradation is typically mediated by what are called "Atypical chemokine receptors" (ACKRs) who can prevent excessive inflammation by acting as specialised chemokine scavengers, leading to chemokine degradation in lysosomal compartments. Whereas ITAC is degraded by ACKR3, no ACKR identified to date is able to bind or degrade the pro-inflammatory chemokine IP-10. We recently found that activated human T lymphocytes efficiently degrade ITAC and IP-10 via CXCR3. Transfection assays in HEK293E cells gave insight into the degradation mechanism. For instance, only the CXCR3A isoform appears to mediate chemokine degradation, while CXCR3B cannot. Furthermore, b-arrestins seem to be required for efficient IP-10 and ITAC degradation. This research has revealed a new function of CXCR3 in T cells – chemokine degradation – suggesting that T cells play a role in inflammatory chemokine gradient regulation. However, the role of CXCR3-mediated chemokine degradation in chemotaxis, immunity or inflammation remains to be assessed.

*LaRoche-Johnston, F. (1); Monat, C. (1); Coulombe, S. (1); Cousineau, B. (1)

(1) Department of Microbiology & Immunology, McGill University, Montreal, Quebec, Canada

Group II introns are large ribozymes that require the assistance of intron-encoded or free-standing maturases to self-splice from their pre-mRNAs in vivo. They can excise as lariats, circles or in a linear form through branching, circularization or hydrolysis respectively. Branching is by far the main and most studied splicing pathway while hydrolysis and circularization have mostly been overlooked. We previously provided the first detailed molecular analysis of the group II intron circularization pathway in vivo showing that circularization is a conserved splicing pathway that occurs concurrently with branching in bacterial cells. Here we show that during circularization in vivo group II intron can capture mRNA fragments at the splice junction of excised intron RNA circles. We found that the captured mRNA fragments are flanked by IBS1/2-like sequences strongly suggesting that they are recognized, during the circularization pathway, by the intron’s EBS1 and EBS2 motifs through base pairing interactions. Our data thus support the incorporation of mRNA fragments at the splice junction of intron RNA circles by a new circularization pathway. The pathway is initiated by the complete reverse splicing of the intron within cellular mRNAs followed by its circularization using an upstream alternative 5’ splice site.

*Mohideen, F. I. (1); Kwan, D. H. (1)

(1) Department of Biology, Centre for Applied Synthetic Biology, Concordia University

Natural products and their derivatives play a major role in pharmaceutical industry. Many small molecule natural products contain sugar moieties that have a great significance upon their bioactivity. Examples include montbretin (anti-diabetic), erythromycin (antibiotic), daunorubicin and its derivatives (chemotherapeutics). These glycosides are synthesized by transferring glycosyl moieties from sugar donors onto aglycones by glycosyltransferases (GTs). To modify or improve the bioactivity via altering glycosylation, synthetic and semisynthetic approaches have been used. In vitro enzymatic methods would be an alternative to avoid multistep, labor-intensive organic routes. To utilize the maximum potential of glycosides, more GTs should be characterized and engineered. Thus, a well developed method for assaying GTs in a high-throughput fashion will be a valuable tool for discovering, studying and engineering GTs through directed evolution. The short term objectives of this project are to develop a methodology for a biphasic glycosyltransferase high-throughput assay and to utilize it to screen various GTs and precursors. Epirubicin is a high value anticancer drug with fewer side effects and is conventionally produced semisynthetically by modifying the glycosylation of a natural product. The long term objective is to utilize the developing assay to engineer a GT enzyme via directed evolution that can synthesize epirubicin.

Moujaber, O. (1); Kodiha, M. (1); Papazova, E. (1); Bednarz, K. (1); Stochaj, U. (1)

(1) Department of Physiology, Faculty of Medicine, McGill University, Montreal

Organ functions decline during aging, and the most profound changes occur in the kidney. Kidneys are continuously exposed to oxidative stress. They are particularly vulnerable to physiological and environmental insults. The proper response to stress is crucial for cell and organ survival. The formation of cytoplasmic stress granules (SGs) is a conserved reaction that helps eukaryotic cells to survive stress. Aging impairs the stress response, but little is known about the underlying mechanisms. It is our goal to define how aging compromises the kidney’s ability to cope with stress. To this end, we developed two models of renal proximal tubule cell aging. They are based on the chemical or pharmacological induction of senescence. We demonstrated that both model systems display hallmarks of aging. Using these models, we assessed SG formation and stress-induced signaling. We showed that aging impairs SG assembly. Moreover, our studies uncovered the underlying molecular mechanisms. Taken together, our research provides a better understanding of the aging-dependent changes in kidney physiology. We identified new biomarkers that can score the stress response in kidney cells. Long-term, this information will help to develop new diagnostic and therapeutic tools to evaluate cellular aging.

*Boudreault, S. (1); Thibault, P. (2); Durand, M. (2); Lapointe, E. (2) ;Lemay, G. (3); Bisaillon, M. (1)

(1) Université de Sherbrooke, Département de biochimie
(2) Université de Sherbrooke, Plateforme de RNomique
(3) Université de Montréal, Département de microbiologie, infectiologie et immunologie

Les virus sont des experts pour modifier l’homéostasie cellulaire. Récemment, plusieurs groupes ont démontré que quelques virus pouvaient modifier l’épissage alternatif (ÉA) de certains transcrits cellulaires. Puisque l’ÉA possède un rôle important de régulation, nous avons émis l’hypothèse que ces changements pourraient être beaucoup plus importants. Pour étudier la modulation de l’ÉA des transcrits cellulaires causée par un virus, des cellules L929 contrôles et infectées avec Réovirus ont été analysées par séquençage d’ARN à haut-débit pour caractériser l’ensemble des événements d’ÉA. Nos résultats ont permis d’identifier 240 événements d’ÉA modifiés de manière statistiquement significative (Q<0,05) touchant 194 gènes. Ces gènes sont enrichis dans les processus liés à la maturation des ARNs et l’épissage alternatif. Ensuite, nous avons investigué la cause de ces changements. Premièrement, nous avons regardé l’expression des facteurs d’épissage. ESRP1 est surexprimé au-delà de 40 fois suite à l’infection. Une expérience de co-culture a permis de déterminer que la surexpression d’ESRP1 ne nécessite pas la présence de Réovirus, mais plutôt la réponse immunitaire cellulaire liée à l’infection. Nous avons démontré que Réovirus induit des changements d’épissage alternatifs chez la cellule-hôte et que cette modulation pourrait provenir de la réponse immunitaire cellulaire déclenchée dans le cadre de l’infection virale.

*Lopes, A.A.(1); English, A.(2)

(1) Department of Chemistry and Biochemistry, Concordia University

Heme proteins are important for many biological process such as cell respiration, transcription, and antioxidant defense. Heme is synthesized in an eight-step process that finalizes with the insertion of ferrous ion (Fe²⁺) into the porphyrin. This reaction is catalyzed by ferrochelatase (FECH), but no heme acceptor that interacts directly or indirectly with FECH has yet been described. Interestingly, cytochrome c peroxidase (Ccp1) is a heme protein that is synthesized in fermenting yeast before heme accumulation. Thus, apoCcp1 may be a heme acceptor of FECH, but these proteins appear to be localized on different sides of the inner mitochondrial membrane. Pet9, a highly abundant ATP/ADP transporter in the inner membrane has additionally been characterized as a heme transporter and was found to be both a Ccp1 and FECH interactor in pulldown studies. My aim is to characterize in detail the interaction between Ccp1, Pet9 and FECH and, as a starting point, I optimized expression of GST-apoCcp1 and of the GST control in BL21(DE3) E. coli cells. I added purified recombinant GST-apoCcp1 as bait or GST as a control to lysates of the mitochondrial-enriched (P10) fraction from 1-day BY4741 yeast cells. To solubilize the inner membrane, 20 mM N-octylglucoside was also added to the P10 lysates. Pet9 and mitochondrial matrix proteins such as aconitase and succinate dehydrogenase were detected in the GST-apoCcp1 pulldowns, which confirms successful solubilization of the membrane. Nevertheless, extensive cleavage of GST-apoCcp1 in the P10 lysates was detected by SDS-PAGE with silver staining. Fresh PMSF, a serine protease inhibitor, was added to P10 fractions to prevent cleavage of GST-apoCcp1, which reduces the sensitivity of pulldown assays. This and other strategies to optimize pulldown assays will be discussed.

*Rahman, M. S. (1)

(1) Concordia University

The enzyme tRNA nucleotidyltransferase (tRNA-NT) is involved in adding cytosine-cytosine-adenine (CCA) to the 3’ end of eukaryotic tRNAs during their maturation, which is required for aminoacylation and protein synthesis. In yeast, this enzyme is defined as a Class II tRNA-NT due to the presence of multiple conserved N-terminal Motifs. Based on available crystal structures of related tRNA-NTs, specific functions have been defined to these motifs. One goal of this project is to better understand the role of Motif C, the least well characterized motif, in enzyme structure and function. Studying tRNA-NT variants containing amino acid substitutions at E189 and D190 in Motif C, shows reduced enzyme activity. Another goal is to understand how an alteration in Motif A (at R64) restores enzyme activity in those low-activity variants of Motif C. Circular dichroism and fluorescence spectroscopic analyses suggest no major changes in structure in the variants suggesting that changes caused by the substitutions act locally. Thermal stability is affected in some variants. Kinetic analyses showed no alterations in substrate binding (K_m) for ATP, CTP or tRNA, but a reduction in turnover number (k_cat) for the 189 and 190 variants, and an increase in kcat in the position 64 double variants. These data suggest that Motif C may play a role in accommodating and orienting the substrates to promote catalysis. Proteolysis experiments using chymotrypsin suggest a reorientation of residues in the R64W variants hinting that this variant causes a change in organization at Motif A that in turn increases catalytic efficiency.

*Sakeer, K. (1); Ispas-Szabo, P. (1); Mateescu, M. A. (1)

(1) Université du Québec à Montréal (UQAM)

The novel Ampholytic CarboxyMethyl-AminoEthyl-starch (CM-AE-St) polymer was synthesized first by starch treatment with sodium monochloroacetate to obtain CM-St and then by treatment with 2-chloroethylamine hydrochloride in order to introduce AminoEthyl (AE) groups. The CM-AE-St was characterized by physical methods, FT-IR, ¹H NMR, SEM, TG, X-ray diffraction and by in vitro drug dissolution. Higher DS for both CM- and AE- groups favor the ability of ampholytic CM-AE-St to control the drugs release of high soluble drugs such as Metformin followed in simulated gastric fluid (SGF) and in simulated intestinal fluid (SIF). For instance, monolithic tablets with CM-AE-St (DS 0.06 for CM and 0.059 for AE groups) and with metformin loading 50% similar shape and weight to the commercial Glumetza®, were able to prolong liberation of active drugs up to 10h, exhibiting a similar dissolution profile to that of commercial product. The presence of both (cationic and anionic) functional groups generates a self-stabilized polymer with improved ability to control the drug delivery. The release profiles show a good fit to Higuchi’s model (r² > 0.99). The release pattern obtained with the ampholytic starch excipient seems to be in good agreement with the United States Pharmacopeia (USP) requirements for metformin controlled release tablets.

*Tchoumi Nerée, A. (1); Pietrangeli, P. (2); Marcocci, L. (2); Ispas-Zsabo, P. (1); Mateescu, M.A. (1)

(1) Department of Chemistry and Centre BioMed, University of Quebec at Montreal.
(2) Department of Chemical Sciences, University of Rome "La Sapienza"

Inflammatory Bowel Diseases (IBD), such as ulcerative colitis and Crohn Disease, are chronic gastrointestinal diseases. In Canada, up to 15% of the population suffer from IBD. The therapies available are mostly based on corticosteroids and on non steroidal anti-inflammatory drugs (NSAID) know to present various undesirable side effects. Diamine oxidase (DAO) is a protein extracted from lentil seedlings. It oxidizes primary biogenic amines (i.e. putrescine and histamine) producing the corresponding aldehydes, NH₄⁺ and H₂O₂. Histamine is a mediator of anaphylactic reactions and a proinflammatory factors. The disequilibrium between the accumulated histamine and the capacity for DAO to generate allergic phenomena and a harmful effect on subjects suffering of IBD. The aim of this project is to characterize the diamine oxydase (DAO) formulated with gastro-resistant excipients for an oral administration to reinforce the endogenous intestinal DAO. A special attention was to characterize the biological impact of the biliary acids on DAO activity. The spectrophotometry, fluorimetry and circular dichroïsme analysis revealed that the cholic acid or deoxycholic acid protect enzyme and prevent the loss of its activity in presence of 0.1M of NaHCO₃ or NaOH. This study shows that cholic and deoxycholic acid may play an important function in maintain DAO activity.

*Ali, M. (1)

(1) Concordia University

Bacterial secondary metabolites represent an important source of antimicrobial agents that could greatly help in human’s battle against pathogens. For example, previous studies indicate that gram-negative bacteria Photorhabdus luminescens produce a number of antibiotics. However, secondary metabolites are highly regulated in bacteria, which leads to difficulties in extraction and isolation. A plausible approach to overcome tight regulation could be to introduce of additional copies of transcription initiation factors or/and enhancer binding proteins. This could potentially upregulate DNA transcription of secondary metabolite gene cluster. Hence, s-54 transcription initiation factor and a constitutively active form of enhancer binding protein DctD were independently used to transform P. luminescens via plasmids. Firstly, P. luminescens transformed with s-54 gene, rpoN, showed no phenotypic difference to wild type. On the other hand, DctD transformation displayed a new product with blue glow under long wave UV light. Further on, LC/MS and tandem MS studies of DctD-positive cell extract show the formation of new compounds and a reduction in the production of others. HPLC-UV-Vis provided UV data corresponding to MS peaks of interest. Future work will be to grow large quantities of DctD-positive P. luminescens, test for antimicrobial activity, and obtain structures via 2D-NMR and/or crystallography.

*Allaire, A. (1); Boivin, G. (2); Bisaillon, M. (1)

(1) Université de Sherbrooke, Département de Biochimie, Sherbrooke, Qc, Canada
(2) Centre Hospitalier de l’Université Laval (CHUL) et Université Laval, Département biologie médicale, Québec, Qc, Canada

Le cytomégalovirus humain (HCMV) est un Herpèsvirus causant une infection latente chez 60% des nord-américains. Sa primo-infection chez les nouveaux-nés et sa réactivation chez les individus immunodéprimés provoquent un impact clinique important. Plusieurs souches résistantes aux antiviraux utilisés sont retrouvées chez certains patients infectés. Ces souches présentent des mutations au niveau du gène viral encodant l’ADN polymérase UL54 du HCMV. L’hypothèse de recherche est que ces mutations affectent la liaison des antiviraux à UL54, les rendant ainsi inefficaces contre le virus. Cette recherche vise à élucider le mécanisme moléculaire de résistance aux antiviraux chez ce pathogène. Jusqu’à maintenant, l’optimisation de l’expression et de la purification de la protéine recombinante UL54 de type sauvage et des diverses versions mutées associées à la résistance aux antiviraux a été réalisée. Par spectrofluorimétrie, il a été possible d’observer que l’affinité d’UL54 de type sauvage et des mutants est similaire pour l’ADNsb. Par contre, l’affinité des mutants pour le dATP est différente si on la compare avec celle d’UL54 de type sauvage. Des résultats préliminaires de l’interaction de l’antiviral foscarnet aux diverses formes d’UL54 ont été obtenus aussi par spectrofluorimétrie. Ceux-ci semblent indiquer que les mutants d’UL54 associés aux résistances lient peu ou pas l’antiviral.

*Brand, C. (1); Votaw, K. (2); McCullagh, M. (2); Geiss, B. (2); Bisaillon, M. (1)

(1) Université de Sherbrooke, Sherbrooke, QC, Canada
(2) Colorado State University, Fort Collins, CO, USA

Le virus du Nil occidental, tout comme le virus de la dengue et le virus Zika, est un virus d'ARNsb transmis par des moustiques. Ces virus font partie des Flavivirus qui causent des dizaines de milliers de décès par année à l’échelle mondiale, et il n’y a actuellement pas de traitement antiviral disponible. Ici nous cherchons à caractériser l'interaction entre les protéines virales NS3 et NS5 qui forment le complexe de réplication en vue de cibler cette interaction pour la découverte de nouveaux composés antiviraux. Un modèle d'interaction entre NS3 et NS5 a été créé par arrimage manuel et soumis à des simulations de dynamique moléculaire. Des résidus impliqués dans des interactions potentielles entre les deux protéines ont été identifiés et mutés. Les effets des mutations sur l’interaction protéine-protéine et sur le niveau de réplication virale ont été mesurés. Une région particulière sur la surface de la protéine NS3 a été identifiée comme jouant un rôle important dans la réplication virale. Un criblage virtuel pour des composés qui peuvent lier cette région sera effectué, et la capacité de ces composés à interférer avec la formation du complexe de réplication virale et donc avec la réplication du génome viral sera évaluée.

*Ducharme, J. (1); Auclair, K. (2)

(1) McGill University

Les cytochromes P450 (CYPs) constituent une famille d’hémoprotéines catalysant des réactions d’oxydoréduction essentielles à la biosynthèse de substances endogènes (stéroïdes, lipides, vitamines) et au métabolisme des xénobiotiques. CYP3A4 est responsable, à lui seul, du métabolisme de 50% des médicaments et il est donc souvent à l’origine d’effets secondaires nuisibles chez le patient du à l’interaction de médicaments co-administrés. CYP3A4 comporte un site actif large et flexible lui permettant de transformer une grande variété de substrats et de lier plusieurs molécules ligands à la fois. Cette particularité complique l’étude du cytochrome par le fait que la fixation de ces différents ligands démontre souvent de la coopérativité lui conférant ainsi une cinétique enzymatique atypique compliquée à décortiquer. Puisque CYP3A4 peut interagir avec plusieurs ligands à la fois, il est difficile de dissocier l’effet de chacun sur le phénomène de coopérativité. Nous proposons une méthode permettant d’attacher de manière covalente diverses molécules de ligands en son site actif permettant ainsi d’isoler l’impact de la fixation du premier ligand sur les interactions coopératives observées. La compréhension des mécanismes sous-jacents à la coopérativité de CYP3A4 contribuera à faciliter le développement de médicaments et l’avancement des connaissances reliées à ce nouveau mécanisme de coopérativité.

*Fortinez, C. (1); Bloudoff, K. (1); Schmeing, M. (1)

(1) McGill University

Non-ribosomal peptide synthetases (NRPSs) are large multimodular mega-enzymes that catalyze peptide bonds resulting in the formation of biologically interesting compounds such as bleomycin (anti-tumor). Each module contains three integral domains including the adenylation domain (A) which transports the substrate to the peptidyl carrier protein (PCP) arm. The PCP domain of the current module and the PCP arm of the previous module will transport their covalently bound substrates to the condensation (C) domain where the peptide bond is catalyzed. The growing peptide chain will eventually be transported to the C domain of the next module where elongation continues. The C domain is sometimes replaced with a cyclization (Cy) domain in non-canonical NRPSs. They are responsible for two reactions. The first involves the formation of a peptide bond. The latter involves forming 5-membered heterocyclic rings with cysteine, threonine and serine side chains resulting in oxazole and thiazole ring formation found in anti-tumor compounds such as epothilone. The function of the Cy domain has not been fully elucidated. However, NRPSs are great in that rearranging different modules can produce novel therapeutic products. Insufficient knowledge of the C and the Cy domain has lead to efforts that result in low product yields. The hope is to do structural and biochemical experiments with the Cy domain to better understand its function.

*Ghilarducci, K. (1); Djerir, B. (1); Desroches, C. (1); Arteau,, J. (1); Bourgault; S. (1); Lussier, M. P. (1)

(1) Université du Québec à Montréal, Département de Chimie, Montréal, QC, H3C 3P8, Canada

Afin de maintenir les cellules en bonne santé, les protéines doivent être convenablement régulées. En effet, des études récentes ont mis en évidence la fonction des enzymes du système de l’ubiquitine (UB) dans divers systèmes cellulaires. Cependant, notre compréhension de la machinerie enzymatique qui contrôle la dégradation, l’activité et la localisation des protéines via le couplage de l’UB reste exceptionnellement limitée. Dans ce contexte, nous voulons déterminer les caractéristiques fondamentales de RNF167, une enzyme du système UB pour laquelle les caractéristiques moléculaires et les propriétés intrinsèques sont extrêmement limitées. Par conséquent, notre objectif est d’identifier et de caractériser les enzymes conjugatrice de l’UB (UBE2) qui sont fonctionnellement actives avec RNF167. Après avoir optimisé la procédure de purification et d’expression, nous avons développé un test d’ubiquitination in vitro pour déterminer les complexes fonctionnels UBE2-RNF167. Nous montrons que RNF167 interagit fonctionnellement avec neuf des vingt-neuf UBE2s testées. En outre, nous démontrons l’interaction physique entre RNF167 et UBE2D1 par l’intermédiaire d’essai de liaison in vitro de type GST. Enfin, notre expérience de Surface Plasmon Resonance montre que la dissociation du complexe UBE2D1RNF167 est instantanée. En résumé, nos résultats révèlent des interactions fonctionnelles entre RNF167 et UBE2s.

*Semana, P. (1); Powlowski, J. (1,2)

(1) Department of Chemistry and Biochemistry, Concordia University, Montreal, QC (2) Centre for Structural and Functional Genomics, Concordia University, Montreal, QC

Ring-cleavage dioxygenases catalyze the critical oxygen-dependent ring-opening reaction in the metabolism of aromatic compounds by bacteria and fungi. While ring-cleavage dioxygenases of bacterial origin have been relatively well-studied, fungal enzymes from this group of enzymes are poorly characterized. Here, we report the functional characterization and identification of residues critical for activity of a novel gentisate 1,2-dioxygenase (GDO) from Aspergillus niger. Using a structural superposition of a homology-based model for the fungal enzyme, and the bacterial GDO template structures, we identified residues potentially involved in catalysis and/or substrate binding based on their positions relative to the bound substrate. We then generated and purified C-terminally hexahistidine-tagged variant proteins of A. niger-GDO, with residues Gln-92, His-150 and Asp-162 substituted by alanine, and residue Leu-166 by Ile. We found that, while single substitution variants H150A and D162A are not catalytically active, they are still able to bind gentisate as shown by a fluorescence-based ligand-binding assay. This loss of catalytic activity is not due to altered structural integrity of the variant proteins, as shown by circular dichroism and fluorescence emission spectra similar to the wild type. Furthermore, based on the observed kinetic parameters, we propose that residue Gln-92 is involved in catalysis but probably not in the initial binding of the substrate since its kcat value is 30-fold lower that of the wild type, with a Km for gentisate not significantly changed. Moreover, L166I had kinetic properties similar to the wild type enzyme indicating that the side chain of isoleucine can function equally well for that of leucine’s in substrate binding and catalysis. This work will serve as basis for further understanding the structure and activity relationships in gentisate 1,2-dioxygenases.

*Barber, A. (1); Gelinas, Y. (1)

(1) Concordia University

As the largest sink for organic carbon (OC) on Earth, marine and lacustrine sediments play a major role in maintaining the global redox balance and are of central importance to the global carbon cycle. The majority of the OC preserved within sediments is intimately associated to the sediment mineral matrix, which is composed primarily of silicate minerals and metal oxides. Redox sensitive, nano-scale iron oxides in particular have a strong affinity for OC, forming stable Fe-OC complexes within oxic surface sediments. In fact approximately 20% of the total sediment organic carbon pool is associated to these reducible iron species, yet the mechanism by which these organo-mineral compounds sequester OC remains unknown. Here we use a combination of synchrotron X-ray techniques (Hard X-ray Microprobing and Scanning Transmission X-ray Microscopy) to determine, for the first time, the proportion of the sediment iron pool that is associated to OC through direct inner-sphere covalent interactions, as well as the nano-scale distribution/composition of iron-bound OC these environments. Through the collection of high spatial resolution images on intact sediment particles coupled to X-ray absorption spectra every ~40 nm across the image, we demonstrate the co-localization of specific organic functionalities and iron oxides on sediments from a variety of depositional environments. Using the Hard X-ray Microprobe we show that between 25.7 and 48.4% of the total reactive iron pool is directly associated to OC through inner-sphere organo-mineral interactions in coastal environments, compared to less than 15.4% for pelagic sediments, demonstrating the importance of this OC sequestration mechanism in coastal settings. This sedimentary ferric pump protects OC during its critical passage across oxic-to-anoxic redox transitions to the more reducing sediment layers in which OC is better preserved on geological time scales.

*Bourgouin, J.-P. (1); Poulhazan, A. (1,2); Zito, F. (2); Arnold, A. A. (1); Warschawski, D. E. (1,2); Marcotte, I. (1)

(1) Université du Québec à Montréal
(2) Centre national de la recherche scientifique, Paris, France

In addition to providing structural integrity to cells and organelles, lipid membranes are the hub of important processes such as ion transport, signalling and trafficking, and constitute one of the first barriers to contaminants. Our laboratory has thus developed a range of experiments designed to study biological cells in vivo by solid-state NMR. The objective of this work was to establish the feasibility of studying the lipid membranes of intact Chlamydomonas reinhardtii by ²H SS-NMR with MAS. Since spectra obtained with non-selective labelling suffer from severe spectral overlap, new selective labelling strategies had to be tested, and their efficiency was probed and quantified. Since sensitivity is also improved by using MAS, we have also addressed the effect of spinning on microalgae viability. We will present a comparative assessment of the membrane rigidity of two different strains of Chlamydomonas reinhardtii, under various growth conditions and temperatures, by in vivo ²H SS-NMR. This opens the way for using 2H MAS NMR as a diagnostic tool for the health of micro algae and other microorganisms.

*Imfeld, A. (1); Gélinas, Y. (1); Ouellet , A. (2)

(1) Concordia University
(2) Centre d'expertise en analyse environnementale du Québec

Crude oil and petroleum products are continually being introduced into the environment during transportation, production, consumption and storage. Source identification of these organic contaminants proves challenging due to a variety of factors; samples tend to be convoluted, compounds need to be separated from an unresolved complex mixtures of highly altered aliphatic and aromatic compounds, and chemical composition and biomarker distributions can be altered by weathering, aging, and degradation processes. The aim of our research is to optimize a molecular and isotopic (δ¹³C, δ²H) method to fingerprint and identify petroleum contaminants in soil and sediment matrices, and to trace the temporal and spatial extent of the contamination event. This method includes the extraction, separation and analysis of the petroleum derived hydrocarbons. Sample extraction and separation is achieved using sonication, column chromatography and urea adduction. Compound identification and molecular/isotopic fingerprinting is obtained by gas chromatography with flame ionization (GC-FID) and mass spectrometer (GC-MS) detection, as well as gas chromatography coupled to an isotope ratio mass spectrometer (GC-IRMS). This method will be used to assist the Centre d’Expertise en Analyse Environnementale du Québec to determine the nature, sources and timing of contamination events as well as for investigating the residual contamination involving petroleum products.

*Morel, E. (1); Tetreault, V. (1); Hauser, C. (2); Slaveykova, V. (3); Wilkinson, K. J. (1)

(1) University of Montreal
(2) St Edward’s university
(3) University of Geneva

Avec des applications croissantes utilisant les éléments de terres rares (ETRs), les formes manufacturées de ces éléments sont susceptibles d’être rejetées dans les matrices environnementales. Le cérium (Ce) constitue l’un des ETRs étant utilisé sous différentes formes physiques ; sous forme ionique (ex. Ce(III)) ou de nanoparticules (ex. CeO₂ NPs). Encore aujourd’hui, il n'est pas établi si les réponses biologiques observées chez les organismes exposés aux NPs d’oxydes de métaux sont induites par les NPs elles-mêmes ou par les produits de leur dissolution. Afin d’analyser la biodisponibilité de différentes formes de Ce pour Chlamydomonas reinhardtii, les cellules algales ont été exposées à du Ce(III) ou des CeO₂ NPs (non-enrobées, enrobées de citrate ou d’acides poly-acrilyques) dans des milieux d’exposition contrôlé à pH 7,0 contenant 0,5 µM de cérium total. Les résultats des analyses de bioaccumulation et de caractérisation/spéciation sont reliés aux réponses biologiques analysées aux niveaux sous-cellulaire et cellulaire via des expériences réalisées par séquençage des ARNs et cytométrie en flux. L’influence des propriétés physico-chimiques des NPs ainsi que l’importance de la concentration en ion libre du Ce en tant que fraction biodisponible majeure du Ce pour C.reinhardtii vont être discutés.

*Rowell, J.A. (1), Wilkinson, K.J. (1)

(1) Laboratoire de biophysicochimie de l'environnement, Université de Montréal

Considérant un intérêt technologique croissant pour les éléments de terres rares (ETR), il apparaît essentiel d’évaluer leur potentiel impact environnemental. En effet, des études relatives au devenir de ces métaux dans l’environnement, et plus spécifiquement sur les facteurs qui influencent leur spéciation et leur biodisponibilité, sont nécessaires. D’après les modèles de toxicité couramment utilisés tels que le Modèle du Ligand Biotique (BLM), la complexation des ions par la matière organique naturelle (MON) devrait réduire la concentration de l’ion libre et ainsi, en diminuer la biodisponibilité pour les organismes aquatiques. De récentes études ont toutefois montré des taux d’accumulation supérieurs aux prédictions pour les ÉTR en présence de ligands organiques simples. Il semble donc pertinent de s’interroger sur le rôle de la MON sur la spéciation et la biodisponibilité des ÉTR. Dans cette étude, une résine d’échange cationique en mode dynamique est utilisée pour déterminer la concentration de l’ion libre, et des expériences de bioaccumulation permettent la détermination des taux d’internalisation des ÉTR dans les algues. Le samarium, un lanthanide intermédiaire, ainsi que l’algue verte unicellulaire Chlamydomonas reinhardtii sont utilisés et les résultats sont comparés avec des modèles de spéciation pour comprendre l’influence de la complexation sur la biodisponibilité des ÉTR.

*Tremblay, S. (1); Hayes P. L. (1)

(1) Department of Chemistry, Université de Montréal, Québec

Atmospheric aerosols, i.e. particulate matter (PM), are a major source of uncertainty in climate models. Due to this uncertainty, it is important to analyze the correlation between the composition, the physical properties (e.g. particle size) and the optical properties of atmospheric aerosols using different instruments. In the Arctic, climate change is much more rapid than the global mean, highlighting the important need for atmospheric measurements in this region. To this end, field measurements of the composition of atmospheric aerosol are currently being performed at the Polar Atmospheric Environment Research Station (PEARL) in Eureka, Nunavut (80N, 86W) to characterize aerosols in the Canadian High Artic. The instruments deployed include two PAXs (Photoacoustic Extinctiometers) that measure aerosol light scattering and absorption at 870 nm and at 405 nm, an AMS (Aerosol Mass Spectrometer), an OPC (Optical Particle Counter) and a SMPS (Scanning Mobility Particle Sizer). Using the data obtained from these instruments, which have been operational since August 2015 until today, it is possible to observe changes in aerosol size distributions and aerosol concentrations as well as concomitant changes in the optical characteristics of aerosols.

*Sommers, J. M. (1); Ma, P. K. (1); Hayes, P. L. (1)

(1) Université de Montréal

Organic aerosols (OA) are a major source of atmospheric particulate matter (PM), which have a complex effect on climate, both globally and in local areas. PM is also detrimental to human health in polluted regions. Some OA mass is emitted directly from industrial, vehicular and cooking sources, which are fairly well understood. Meanwhile, secondary organic aerosols (SOA) are formed from gaseous precursors and are relatively poorly understood, which makes it difficult to assess their impact on health and climate. SOA models prior to 2007 underestimated the mass of SOA formed by a factor of 10 or greater, while more modern models have better accuracy, they use poorly-constrained chemical mechanisms, which have resulted in other characteristics of SOA (i.e. oxygen to carbon ratio, formation rates) being poorly predicted by the models. In order to improve SOA modeling, we aim to marry chemically sound oxidation mechanisms with accurate SOA mass yields for speciated precursors in a customized box model. The results of this study are being applied to experimental measurements of SOA formed by emissions from the development of the Athabasca oil sands in order to better understand the atmospheric effects of continued extraction of oil in Northern Alberta.

*Copp W. (1); Wilds, C. J. (1)

(1) Concordia University

Recently, a high resolution structure of the polyadenosine (poly rA) double helix was determined via X-ray crystallography. Crystallization setups of rA11 under neutral pH conditions (pH 7.0) in the presence of ammonium cations gave crystals that diffracted to 1 Å resolution. Each asymmetric unit was found to contain one parallel duplex of rA11 with ten base pairs per helix and a single nucleotide overhang at each end which could pair with the overhang of another duplex forming a continuous helix in the crystal. For 18 of the nucleotides in the duplex, electron density was observed for a molecule optimally positioned to form three hydrogen bonds with a purine N1 atom and a phosphate oxygen of two nucleotides involved in A-A base pairing and to the phosphate of a preceding nucleotide. This molecule was believed to be an ammonium cation, whose role in stabilizing this structure was verified by UV thermal denaturation (Tm) experiments. We were curious about the influence of the sugar portion of the nucleotide to form this homopolymeric duplex. Oligoadenylates containing various sugar modified nucleotides have been prepared and their influence on the stability and structure of this duplex will be described.

*Fan, W. (1); Tong, X. (1); Farnia, F. (1); Zhao, Y. (1)

(1) Département de Chimie, Université de Sherbrooke, QC, Canada

Functional polymer nanoparticles have attracted much attention because of their potential applications in many areas such as energy, biosensors and high performance materials. However, the general polymeric nanoparticles with size over 50nm still cannot satisfied some specific requirements. Recently, single-chain nanoparticle (SCNPs), a class of specific nanoparticles which are formed by one polymer chain via intramolecular crosslinking-induced collapse, obtained highly interest due to their small size (1.5-20nm) and related distinct properties. [1] Here, we will report a class of sub-20nm CO₂-responsive polymeric single-chain nanoparticles via photo-induced coumarin based intra-chain crosslinking of a single linear precursor polymer chain. The well-defined SCNPs exhibit reversible size-tunable and low critical soluble temperature (LCST) tunable by CO₂ and N₂ bubbling. We further prepared CO₂-responsive tadpole-like janus SCNPs, and their spherical self-assemblies also exhibit reversible size-tunable in water. What’s more, the SCNPs were used as a nano-reactor to synthesis gold nanoparticles (AuNPs) in situ. The rate of AuNP formation was found to be increased by CO₂ bubbling and realized rate switchable of the AuNP preparation by reversible bubbling CO₂ and N₂. This provides a means of gas controllable the kinetics of AuNP formation.

[1] A. M. Hanlon, C. K. Lyon, and E. B. Berda, Macromolecules 2016, 49, 2-14

Rodriguez Burbano, D. C. (1)*; Capobianco, J. A. (2)

(1) Concordia Department of Chemistry and Biochemistry
(2) Centre for Research in Nanoscience, Concordia University

Persistent luminescent nanophosphors are nano-sized materials based on the formation of defects in an insulator host crystal. The presence of these defects generate ‘metastable states’ located between the conduction and valence band that act as electron trapping sites. When the nanophosphors are irradiated with a high-energy (UV light), the absorbed energy can be stored as trapped electrons in the trapping sites. The stored energy may be released upon thermal and/or photo-stimulation, resulting in an intense emission in the visible region. The mechanisms for storage and subsequent energy release are complex and not totally understood. Furthermore, obtaining a stable persistent nanophosphor in the red region exhibiting a persistent luminescence decay of more than one hour has proven to be a difficult task. In this presentation, the synthesis, characterization and optical properties of the CaS:Eu²⁺/Dy³⁺ red persistent luminescent nanophosphor are reported. The nature of the electron trap sites and the trapping and de-trapping mechanisms were studied by wavelength resolved thermally stimulated luminescence. The generation of strong red light emission following NIR excitation of the CaS:Eu²⁺/Dy³⁺ nanophosphor is demonstrated. Moreover, we present the surface modification of the CaS:Eu²⁺/Dy³⁺ nanophosphor for its potential use as a luminescent probe for in vivo optical imaging.

*McTaggart, A. (1); Cuccia, L. (1)

(1) Concordia University

The limited symmetry repotoire of conventional crystallography poses a fundamental challenge in materials chemistry. In this regard, the ability to direct the self-assembly of nanostructures represents one of the ways in which this problem might be overcome, and could lead to the development of complex materials and devices grown in a parallel fashion. Biomorphs, which are characterized by their smoothly curved morphologies extending beyond the constraints of crystallographic symmetry, are one class of inorganic materials that are being explored for their nanoscaled components formed via a self-assembly process. The coprecipitation of carbonate and silica , under the influence of atmospheric CO₂ in a basic reaction mixture of barium chloride (BaCl₂)/strontium chloride (SrCl₂ ) and sodium silicate (Na₂SiO₃), can lead to biomorphs with very interesting morphologies such as helices, cardioidal sheets and vases. In this work, we will investigate the CO₂ gas-diffusion system en route to the formation of silica-carbonate microstructures under varying parameters of CO₂ concentration, pH and temperature. Furthermore, higher-order microarchitectures will be assembled in sequential growth steps by switching between desired reaction conditions, thereby nucleating and stacking structures onto previously formed ones. Finally, the use of chiral amino acids as templating guides to influence the chirality of the double spirals formed at pH 11.2 will be explored.

*Medina Tato, S. (1); Reber, C. (2); Castillo Blum, S. (1)

(1) Universidad Nacional Autónoma de México
(2) Université de Montréal

Lanthanide oxides nanoparticles (<50nm) with an organic surface agent were synthesized and characterized. The lanthanides employed were NdIII, SmIII, EuIII, GdIII, Tb(III,IV) and DyIII and the surface agent was 2,3-dihydroxyquinoxaline. The synthesis of the oxides is carried out through a sol-gel method and the addition of the surface agent is done at ambient conditions. The characterization includes powder XRD, TEM, SEM, FT-IR and TGA for the lanthanide oxide nanoparticles by themselves and solid state diffuse reflectance, luminescence (at room temperature, 200K and 100K) and Raman spectroscopies for both lanthanide oxides with and without the capping agent. Most of the lanthanide oxides nanoparticles present the characteristic narrow luminescence f-f transitions, except for TbO1.81 (pdf [00-075-0275]), a blend of TbIII and TbIV. Terbium (IV) has been found to not present luminescence[1]. Some compounds with the organic surface agent show broad bands related to the organic agent, while EuIII, SmIII and NdIII show f-f luminescence transitions that differ in some peaks in intensity and shape to the ones observed in their corresponding lanthanide oxide spectra.

[1] C. Young In and S. Youngku, RSC Adv., 2014, 4, 31155

*Sabri, T. (1); Pawelek, P. D. (1); Capobianco, J. A. (1)

(1) Concordia University, Natural Science and Engineering Research Council (NSERC), Centre Quebecois sur les materiuax fonctionnels (cqmf)

Photodynamic therapy is least invasive treatment in cancer therapy. The technique requires photoactive molecule “Photosensitizer” that is activated by light to produce reactive oxygen species which cause in situ cell death. There are two major drawbacks that limit the application of photodynamic therapy. First, the use of high energy excitation light that weakly penetrates tissues, allowing the technique to be suitable only for superficial treatments. Second, poor selectivity of the photosensitizer for cancer cells, as a consequence damaging healthy tissues or cells. Our research utilizes lanthanides upconverting nanoparticles that are excited with lower energy light and emit in the UV,visible and near infra-red region of the spectrum. The advantages of this optical property are that it permits light to penetrate deeper in tissues, and can activate a number of photosensitizers that have different excitation profiles. In order to render the particles suitable for biological applications, and to enhance selectivity of tumor tissues, the surface of lanthanides doped nanoparticles are coated with protein albumin. In addition, the photosensitizer, Rose Bengal, is conjugated to the albumin coated nanoparticles. Thus, the nanoconstruct has a dual effect the production of singlet oxygen, and unique selectivity for cellular uptake by cancer cells.

*Wyszatko, K. (1); DeWolf, C. (2)

(1) McMaster University
(2) Concordia University

Drop profile- analysis tensiometry (PAT) of bolaamphiphile SiBA-10 has shown a shift in the elastic modulus when the monolayer is in the presence of subphase containing amines. Specifically, this shift shows a larger elastic modulus achieved at lower surface pressures. It was found that tris (2-aminoethyl) amine (0.1M, pH 10) produces the largest shift, presumed to be evidence for the presence of crosslinking between SiBA-10 and tris (2-aminoethyl) amine molecules. Less pronounced effects were demonstrated by tris (0.1M), ethylenediamine (0.01M), and ethanolamine (0.01M) (all at pH 10), reasoned to still be because of binding between subphase and monolayer, but not necessarily crosslinking. This elasticity data is in agreement with isotherms our group has previously collected for SiBA-10 on these amine subphases. Isotherms of three amino-functionalized lipids HO10, TT10, and TO10 (AFLs) were obtained using a Langmuir Trough. It was found that on subphase consisting of GdnHCl, a known hydrogen bond disruptor, the isotherms of the lipids shifted to higher surface pressure. Mixtures of the AFLs and SiBA-10 molecules in ratios of 1:1 and 2:1 were found to produce isotherms unlike those of either constituent; this hybrid nature is proposed to be due to crosslinking between constituents at high surface pressures.