RESUMO
The process of proton transfer across the membrane via the external proton channel in bacteriorhodopsin is considered. A possible amino acid composition of the channel is suggested and the step-by-step mechanism of proton transfer is proposed which agrees with the experimental data. The rate of proton transfer between fixed centers at several chains of the channel was estimated for which the spectroscopic data are available.
Assuntos
Bacteriorodopsinas/química , Halobacterium salinarum/química , Modelos Químicos , Prótons , Transporte de Íons , TermodinâmicaRESUMO
The results of quantum chemistry calculations of the total energy and proton position in tyrosine-histidine system in a water-oxidizing complex are presented. On the basis of these calculations, the submolecular mechanism of the initial stage of the electron coupling was proposed.
Assuntos
Plantas/metabolismo , Água/metabolismo , Transporte de Elétrons , Água/químicaRESUMO
In this work we consider the coupling of electron and proton transfer near Q(B) in the reaction center (RC) of photosystem II (PS2). We have carried out the calculations of the energy levels and proton density in the system Q(B)(-) Histidine L190. It is shown that the proton of the histidine forms the H-bond with twice-reduced Q(B)(2-). Based on these calculations, we propose a new explanation of the coupling between the electron and proton transfer.
Assuntos
Benzoquinonas/química , Histidina/química , Modelos Biológicos , Modelos Químicos , Complexo de Proteína do Fotossistema II/química , Proteínas de Plantas/química , Benzoquinonas/metabolismo , Sítios de Ligação , Transporte Biológico/fisiologia , Simulação por Computador , Transporte de Elétrons , Histidina/metabolismo , Oxirredução , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Plantas/metabolismo , Ligação Proteica , Prótons , Teoria QuânticaRESUMO
The coupling of electron and proton transport in the vicinity of the secondary quinone QB in the reaction center of bacteria and photosystem II of higher plants was investigated. The energy levels and wave functions of the proton in the system QB--histidine L 190 were calculated. It was shown that the proton of histidine forms a hydrogen bond with the doubly reduced quinone QB2-. A new scheme of proton transport through histidine L 190 and its coupling with electron transport was proposed.