title: Effect of deuteration and cryosolvents on the energy transduction in primary processes of photosynthesis.
abstract: Effects of cryosolvents and D2O/H2O substitution on the reaction centres (RCs) isolated from photosynthetic bacteria were studied with respect to the role of intra-protein hydrogen bonds in the primary photosynthetic electron transfer. As a result of such treatment of RCs, the charge separation rate between the photoactive bacteriochlorophyll (P2 dimer) and bacteriopheophytin and the rate of electron transfer to the primary quinone slowed down. The energy migration rate from bacteriopheophytin (BPheM), inactive in electron transport, to P2 decreased as well. Although cryosolvents can shift the redox potential of the photoactive pigment, there is no direct correlation between the P2 potential and the effects of these modifying agents on the photosynthetic process in RCs occurring with participation of P2. The removal of H subunit from the pigment-protein complex results in the pronounced weakening of the dimethyl sulfoxide modifying effects on the RC hydrogen bonds. The role of structural and dynamic state in the functioning of the photosynthetic bacterial RCs is analyzed. Relaxation processes in purple bacteria RCs accompanying the primary picosecond steps of energy transformation proceed with the participation of small proton-containing molecular groups in the immediate surroundings of electron transfer carriers. In this paper, we present results concerning mechanisms of primary photosynthetic steps, which were initiated by A. A. Krasnovsky and have been studied for several years at the Department of Biophysics. This paper is dedicated to the memory of our teacher Prof. A. A. Krasnovsky.
authors.affiliation: Department of Biology, Moscow Lomonosov State University, Russia.
authors.forename: V V
authors.initials: VV
authors.lastname: Gorokhov
authors.forename: P P
authors.initials: PP
authors.lastname: Knox
authors.forename: B N
authors.initials: BN
authors.lastname: Korvatovsky
authors.forename: V Z
authors.initials: VZ
authors.lastname: Paschenko
authors.forename: N I
authors.initials: NI
authors.lastname: Zakharova
authors.forename: A B
authors.initials: AB
authors.lastname: Rubin
mesh_terms: D001429:Bacteriochlorophylls / Q000378:metabolism; D002856:Chromatophores / Q000187:drug effects / Q000378:metabolism; D003451:Cryoprotective Agents / Q000494:pharmacology*; D017666:Deuterium Oxide; D019281:Dimerization; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D008956:Models, Chemical; D010674:Pheophytins / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D045322:Photosynthetic Reaction Center Complex Proteins / Q000187:drug effects / Q000378:metabolism*; D012242:Rhodobacter sphaeroides / Q000187:drug effects / Q000378:metabolism*; D012997:Solvents / Q000494:pharmacology; D014867:Water
chemical_list: D001429:Bacteriochlorophylls; D003451:Cryoprotective Agents; D045342:Light-Harvesting Protein Complexes; D010674:Pheophytins; D045322:Photosynthetic Reaction Center Complex Proteins; D012997:Solvents; D014867:Water; D017666:Deuterium Oxide; D004121:Dimethyl Sulfoxide