Laszlo Kalman, PhD

Associate Professor, Physics
Undergraduate Program Director, Physics
Co-op Academic Director, Physics
Fellow, Science College

Contact information

Email:

Laszlo.Kalman@concordia.ca

Website:

Research Group website

Biography

Our research is focused on the study of the primary processes of photosynthesis. Photosynthetic organisms have made life possible on Earth and had contributed undoubtedly to development of oxygen dependent life on our planet.

Photosynthesis supplies our food, oxygen and the currently used energy sources, since the carbon found in fossil fuels, such as natural gas, crude oil, and coal were fixed from atmospheric carbon-dioxide by the photosynthetic process millions of years ago. The reactions leading to the energy conversion and storage take place in specially organized membrane-bound pigment-protein complexes, termed reaction centers. We are particularly interested in the link between the light-induced electron transfer and the accompanying protonational reactions occurring in these centers.

Education

PDF Arizona State University (USA)
PhD University of Szeged (Hungary)

Research interests

Molecular Biophysics/Biophysical Chemistry, Bioenergetics, Photosynthetic Energy Conversion

Awards

2006 Canada Foundation for Innovation, Leaders Opportunity Fund Award
2006 Petro-Canada Young Innovator Award

1999 Young Investigator Award at Gordon Research Conference on Photosynthesis: Biochemical aspects, New Hampshire (USA)

Teaching activities

Courses

PHYS 260, Introductory Biophysics
PHYS 334, Thermodynamics
PHYS 460/660 Chemical Aspects of Biophysics

Research

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.

Selected publications

Samaei, A., Deshmukh, S.S., Protheroe, C., Nyeki, S., Tremblay-Ethier, R-A., Kalman, L: Photoactivation and conformational gating for manganese binding and oxidation in bacterial reaction centers. Biochimica et Biophysics Acta (BBA)-Bioenergetics, 1864, 148928 (2023)
Deshmukh, S.S. and Kalman, L.: Tuning the redox potential of the primary electron donor in bacterial reaction centers by manganese binding and light-induced structural changes. Biochimica et Biophysica Acta (BBA)- Bioenergetics, 1861, 148285 (2020)
Modafferi, D., Zazubovich, V., Kalman, L.: Bound detergent molecules in bacterial reaction centers facilitate detection of tetryl explosive. Photosynthesis Research 145, 145-157 (2020)
Deshmukh, S.S., Protheroe, C., Ivanescu, M.-A., Lag, S., and Kalman, L.: Low potential manganese ions as efficient electron donors in native anoxygenic bacteria. Biochimica et Biophysica Acta (BBA)-Bioenergetics 1859, 227-233 (2018)
Dong, M., Babalhaveji, A. Hansen, L.J., Kalman, L., Woolley, G.A.: Red, far-red and near infrared photoswitches based on azonium ions. Chemical Communications, 51, 12981-12984 (2015)
Balhara, V., Deshmukh, S.S. Kalman, L., Kornblatt, J.A: The interaction of streptococcal enolase with canine plasminogen: The role of surfaces in complex formation. PLOS ONE, 9, e88395 (2014)
Milano, F., Trotta, M., Dorogi, M., Fisher, B., Giotta, L., Agostiano, A., Maróti, P., Kalman, 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)
Deshmukh, S.S., Tang, K., Kalman, L: Lipid Binding to the Carotenoid Binding Site in Photosynthetic Reaction Centers,Journal of the American Chemical Society (JACS) 133, 16309-16316 (2011)
Deshmukh, S.S., Akhavein, H., Williams, J.C. Allen, J.P., Kalman, L: Light-Induced Conformational Changes inPhotosynthetic Reaction Centers: Impact of Detergents and Lipids on the Electronic Structure of the Primary Electron Donor, Biochemistry 50, 5249-5262 (2011)
Deshmukh, S.S., Williams, J.C., Allen, J.P., Kalman, L: Light-Induced Conformational Changes in Photosynthetic Reaction Centers: Redox Regulated Proton Pathway Near the Dimer, Biochemistry 50; 3321-3331 (2011)
Kalman, L. Williams, J.C., Allen, J.P.: Energetics for Oxidation of a Bound Manganese Cofactor in Modified Bacterial Reaction Centers, Biochemistry 50; 3310-3320 (2011)
Deshmukh, S.S., Williams, J.C., Allen, J.P., Kalman, L: Light-Induced Conformational Changes in Photosynthetic Reaction Centers:Dielectric Relaxation in the Vicinity of the Dimer, Biochemistry 50; 340-348 (2011)