Concordia University

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Laszlo Kalman Research Group

about

Our group uses an interdisciplinary approach that stems from concepts in physics, chemistry, and biology to study photosynthetic processes at the molecular level.

We specialize in:

  • monitoring light-induced electron and proton transfer reactions in photosynthesis
  • study of lipid-protein interactions
  • artificial membrane characterization
research
Study of the primary processes of photosynthesis

A large family of photosynthetic organisms is capable of the catalytic conversion of the water into molecular oxygen and hydrogen-ions. This process uses inexhaustible resources, such as sunlight, water, and carbon dioxide and provides an example of a unique natural biocatalyst.

Thorough understanding of the natural solar energy conversion is essential in the process of developing artificial energy converters for sustainable future energy production. The reactions leading to the energy conversion and storage take place in specially organized membrane-bound pigment-protein complexes, termed reaction centers. The energy conversion in these enzymes is secured primarily trough transporting electrons and protons across their natural membranes.

We are particularly interested in the link between the light-induced electron transfer and the accompanying protonational reactions occurring in these centers during the early stage of the energy conversion process. We use an interdisciplinary approach to detect and modify these reactions that can connect concepts from physics, chemistry and biology. We grow and harvest photosynthetic organisms, isolate and purify the reaction center protein. The membrane environment of the isolated proteins is systematically altered in order to maximize the efficiency of the electron and proton transfer reactions.

The biophysical characterization involves transient and steady state optical spectroscopy to determine the kinetics of the individual reaction steps from nanoseconds to minutes time scale and dual polarization interferometry to follow the conformational rearrangement of the protein in real time and in atomic resolution.

Why study photosynthesis? Nature's photosynthetic process has been the primary solar energy conversion on Earth for 3.5 billion years and has a great potential to inspire the development of man-made solar energy converters.

Representative publications

  1. M. Dong,  A. Babalhavaeji,  M. J. Hansen,  L. Kalman, G. A. Wooley, Red, far-red, and near infrared photoswitches based on azonium ions. Chem. Comm. 51, 12981-12984 (2015)

  2. V. Balhara, S. S. Deshmukh, L. Kalman, J. A. Kornblatt, The Interaction of Streptococcal Enolase with Canine Plasminogen: The Role of Surfaces in Complex Formation​, Plos One 9, e88395 (2014)

  3. F. Milano, M. Trotta, M. Dorogi, B. Fischer, L. Giotta, A. Agostiano, P. Maroti, L. Kalman, L. Nagy: Light induced transmembrane proton gradient in artificial lipid vesicles reconstituted with photosynthetic reaction centers, J. Bioen. Biomemb. 44. 373-384 (2012)

  4. S. S. Deshmukh, K. Tang, and L. Kalman: Lipid Binding to the Carotenoid Binding Site in Photosynthetic Reaction Centers, J. Am. Chem. Soc. 133, 16309-16316 (2011)

  5. L. Kalman, J. C. Williams, and J. P. Allen: Energetics for Oxidation of a Bound Manganese Cofactor in Modified Bacterial Reaction Centers, Biochemistry 50; 3310-3320 (2011)

  6. S. S. Deshmukh, J. C. Williams, J. P. Allen, and L. Kalman: Light-Induced Conformational Changes in Photosynthetic Reaction Centers: Redox Regulated Proton Pathway Near the Dimer, Biochemistry 50; 3321-3331 (2011)
Group2

Graduate students

Current
  • Daniel Modafferi (co-supervised)
  • Ali Samaei (co-supervised)
Former
  • Charles Protheroe (MSc, graduated 2016)
  • Matei-Alexandru Ivanescu (MSc, graduated 2014)
  • Sasmit Deshmukh (PhD, graduated 2013; MSc, graduated 2009)
  • Kai Tang (MSc, graduated 2008)
  • Tibor Janosi, MSc, University of Szeged, Szeged, Hungary (2000)

Visiting (Former)
  • Dr. Laszlo Nagy, visiting professor, University of Szeged, Institute of Medical Physics and Biophysics (2007)
Postdoctoral Fellows (Former)
  • Dr. Sasmit Deshmukh (2013-2015)
  • Dr. Erick Gonzalez-Labrada (2008-2009)
Undergraduate and summer students
  • Joanne Ramil
  • Enkjin Batdorj
  • Nhat Pi Pham (2015)
  • Marc Hegedus (2014)
  • Sarah Lag (Honors, 2014; USRA 2014; USRA 2013)
  • Dylan Derome (2014)
  • Giuseppe Ramacieri (2013)
  • Lindsay Gossip (2013)
  • Andrew Proppe 2013, SCOL 290
  • Giuseppe Ramacieri 2013, PHYS 497
  • Edgar Galvez 2013, PHYS 497
  • Lindsey Gossip 2013, SCOL 390
  • Melissa Valente-Paterno 2012, SCOL 290
  • Kyle O'Grady 2012, PHYS 497
  • Robyn Phillips 2012, PHYS 497
  • Laurent MacKay 2010-2012, USRA, PHYS 497
  • Diana Di Marco 2010
  • Alexandru Matei Ivanescu 2010
  • Amanda Beyle 2009
  • Michael Hollz-Mullholland 2009
  • Felix Sidochine 2009
  • Rhoda Solazzo 2009
  • Parhzad Torfehnezhad 2009
  • Nedaa Asbah 2008
  • Wael Chanab 2008
  • Fiona Allum 2007
  • Pierre Bohec 2007
  • Lila Karpowicz 2007
  • Patrick Malka 2007
  • Pouya Mesbah-Ardakani 2007
Dual Polarization Interferometer
dpi

Dual Polarization Interferometry (DPI) is an emerging analytical biophysical technique that allows changes in the structure to be followed and quantified in real time. The applied method simultaneously resolves the changes in thickness and surface density in atomic resolution by probing the structure in one dimension using non-diffractive optics.


UV-VIS-NIR Spectrophotometer
uvkalman

Spectrophotometer with a large wavelength range (175-3300 nm) and ultra low photometric noise levels (10‑5 absorption units). The temperature can be controlled from 0-100 °C with a Peltier element.


Miniaturized Laser Flash Photolysis System
mLFP

Transient absorption spectrophotometer with capabilities to measure time resolved absorption changes from 30 ns to 10 s between 330-900 nm.


Perkin-Elmer MP44 spectrofluorimeter
perkin

Perkin-Elmer MP44 spectrofluorimeter interfaced with a LeCroy WaveSurfer 422 digital storage oscilloscope. The web-enabled interface program was written by the NanoScience Group facility manager Dr. Rolf Schmidt.

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