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Molecular Biophysics Research Group

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 and
  • Artificial membrane characterization.

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.

Group members 2016 (l-r) Chuck Protheroe, Dr. Laszlo Kalman and Sasmit Deshmukh

Principal investigator

Laszlo Kalman

Associate Professor, Physics


Graduate students
Postdoctoral Fellows
  • Dr. Sasmit Deshmukh (2013-2015)
  • Dr. Erick Gonzalez-Labrada (2008-2009)
  • Dr. Laszlo Nagy, visiting professor, University of Szeged, Institute of Medical Physics and Biophysics (2007)
Undergraduate and summer students
  • Sarah Nyeki (Winter 2019), visiting Physics BSc student from University of Toulouse 3: Paul Sabatier, France. Biophysical characterization of a membrane protein isolated from non-toxic photosynthetic bacterium.
  • Sevag Pilavdian (Summer 2019) BSc student in Chemistry, SCOL 290, Directed and Independent Study I: Investigation into the Role of bis-tris Propane in the pH-dependence and Redox Potential of Manganese Complexes.
  • Fadi Touma (September 2018-April 2019), BSc student in Biology, SCOL 391, Directed and Independent Study II: Effect of tetryl on the charge recombination kinetics in bacterial reaction center.
  • Yves Lorand (September 2018-April 2019), BSc student in Biology, SCOL 391, Directed and Independent Study II: Investigation into the origins of oxygenic photosynthesis: Efficiency of bicarbonate coordinated manganese ions as electron donors in bacterial reaction centers.
  • Rose-Ange Tremblay-Ethier (Summer 2018), B.Sc. student in Psychology, SCOL 391, Directed and Independent Study II: Impact of suboptimal manganese concentration on electron transfer in bacterial reaction center: One step closer to understanding photosynthesis.
  • Kelly Burchell Reyes (2017), SCOL 391
  • Isabella Iasenza (2017), SCOL 391
  • Geoffrey Unger (2017), PHYS 497
  • Enjkin Batdorj​ (2016), SCOL 290
  • Joanne Ramil (2016), SCOL 390
  • Nhat Pi Pam (2015), SCOL 290
  • Marc Hegedus (2014), PHYS 497
  • Cynthia Messina (2014), SCOL 290
  • Derome Dylan (2014), SCOL 290
  • Braedan Donaldson (2014), SCOL 390
  • Sarah Lag (2013-2014), SCOL 390, NSERC USRA 2x, CHEM 450
  • 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)

Perkin-Elmer MP44 spectrofluorimeter

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

Miniaturized Laser Flash Photolysis System

Dual Polarization Interferometer

Representative publications

  1. Deshmukh, S. S., Protheroe, C., Ivanescu, M.-A., Lag, S. & Kálmán, L. Low potential manganese ions as efficient electron donors in native anoxygenic bacteria. Biochimica et Biophysica Acta (BBA) - Bioenergetics 1859, 227–233 (2018). doi:10.1016/j.bbabio.2018.01.002
  2. Dong, M., Babalhavaeji, A., Hansen, M. J., Kálmán, L. & Woolley, G. A. Red, far-red, and near infrared photoswitches based on azonium ions. Chem. Commun. 51, 12981–12984 (2015). doi:10.1039/C5CC02804C
  3. Balhara, V., Deshmukh, S. S., Kálmán, L. & Kornblatt, J. A. The Interaction of Streptococcal Enolase with Canine Plasminogen: The Role of Surfaces in Complex Formation. PLOS ONE 9, e88395 (2014). doi:10.1371/journal.pone.0088395
  4. Milano, F., Trotta, M., Dorogi, M., Fischer, B., Giotta, L., Agostiano, A., Maróti, P., Kálmán, L. & Nagy, L. Light induced transmembrane proton gradient in artificial lipid vesicles reconstituted with photosynthetic reaction centers. Journal of Bioenergetics and Biomembranes 44, 373–384 (2012). doi:10.1007/s10863-012-9435-2
  5. Deshmukh, S. S., Tang, K. & Kálmán, L. Lipid Binding to the Carotenoid Binding Site in Photosynthetic Reaction Centers. J. Am. Chem. Soc. 133, 16309–16316 (2011). doi:10.1021/ja207750z
  6. Deshmukh, S. S., Williams, J. C., Allen, J. P. & Kálmán, L. Light-Induced Conformational Changes in Photosynthetic Reaction Centers: Redox-Regulated Proton Pathway near the Dimer. Biochemistry 50, 3321–3331 (2011). doi:10.1021/bi200169y
  7. Tang, K., Williams, J. C., Allen, J. P. & Kálmán, L. Effect of Anions on the Binding and Oxidation of Divalent Manganese and Iron in Modified Bacterial Reaction Centers. Biophysical Journal 96, 3295–3304 (2009). doi:10.1016/j.bpj.2009.01.027
  8. Kálmán, L., Williams, J. C. & Allen, J. P. Comparison of bacterial reaction centers and photosystem II. Photosynthesis Research 98, 643 (2008). doi:10.1007/s11120-008-9369-z
  • PHYS 204, Mechanics
  • PHYS 206, Waves and Modern Physics
  • ​PHYS 260, Introductory Biophysics
  • PHYS 334, Thermodynamics
  • PHYS 460/660, Chemical Aspects of Biophysics
  • CHEM 234, Physical Chemistry I
  • Chem 335, Biophysical Chemistry
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