Dynamic models for the electron transfer processes in thylakoid membranes. Chapter 18 in: Photosynthesis: Molecular Approaches to Solar Energy Conversion. Shen JR, Satoh Ki, Allakhverdiev S (Eds.) Springer, 2021, p. 465-498.• ISBN: 978-3-030-67407-6книга
Аннотация:Primary photosynthetic processes are actively studied both experimentally and with the help of mathematical models. The content in this chapter is mainly based on the results of recent work on the kinetic and multiparticle modeling of processes in the photosynthetic membrane, done at the Department of Biophysics of the Biological Faculty, Lomonosov Moscow State University, Moscow, Russia. Using the methods of kinetic modeling based on the systems of ordinary differential equations (ODEs), for the states of photosynthetic multi-enzyme complexes, and the mass action law equations, for mobile carriers and the "rule-based" kinetic Monte Carlo method, made it possible for us to reproduce the kinetics of fluorescence induction curves and redox transformation of the photoactive pigment P700 in the time range from 100 ns to dozens of seconds. Unlike the most existing models, where the fluorescence signal is assumed to be proportional to the concentration of the PSII acceptor QA in the reduced state, the intensity of the fluorescence signal is regarded here as being proportional to the concentration of the excited photosynthetic reaction centers of the Photosystem II (PSII). Analysis of simulations for different types of photosynthetic organisms under different experimental conditions such as under different illumination regimes, in the presence of inhibitors, and under stress conditions, made it possible for us to reveal the role of individual (electron) carriers in the formation of the induction curves of chlorophyll (Chl) a fluorescence and the P700 redox transformations. The fitting of the model curves to the experimental data made it possible for us to quantify the rate constants of reactions, including that of the non-radiative thermal relaxation process, which could not be directly measured experimentally. We used the multiparticle Brownian methods coupled to reveal the role of electrostatic interactions and conformational motions in the transfer of an electron from the cytochrome complex to the molecule of the mobile carrier of plastocyanin. To elucidate molecular mechanisms underlying switching between electron flows on the acceptor side of PSI we have developed direct multiparticle models of competitive interactions between electron acceptors ferredoxin:NADP+ reductase (FNR) and hydrogenase which compete for an electron from Fd.