Moscow, Moscow, Russian Federation
Structural dynamic (kinetic) and agent (multi-particle Brownian) models are used to study the role of pH in the regulation of electron fluxes in the areas of Photosystem II and PhotosystemI when switching the normal mode of active photosynthesis and carbon fixation to the regime of inactive photosynthesis and the production of molecular hydrogen. A multiscale kinetic model describes electron fluxes in PS II, an increase of the proton concentration in the stroma, and the reduction of the plastoquinone pool in the photosynthetic pathway due to the chloro-respiration chain. Based on this model a kinetic mechanism of the jump in the activity of Photosystem II, the stromal acidification in the Photosystem II region and the switching of the electron flow to the path of chloro-respiration is proposed. Multiparticle Brownian models describe the competitive interaction of ferredoxin molecules, which take electrons from PSI, to alternative acceptors: NAD(P)H (CO2 fixation pathway) and hydrogenase (hydrogen production path). The analysis of the results of multiparticle modeling and electrostatic properties of interacting molecules showed that the electron flux from ferredoxin to hydrogenase increases at alkaline pH values (~ 8-8.5) in the vicinity of the Photosystem I acceptor site. The results obtained confirm the hypothesis about the regulatory role of local pH values, widely discussed in the literature in the processes of photosynthesis.
photosynthesis, electronic transport, hydrogen-production from microalgae, kinetic models, multiparticle Brownian models, ferredoxin
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