[Effect of energy status of hydrogen bond protons on the rate of electron transfer in photosynthetic reaction centers].
We present here a theoretical interpretation of the temperature dependence of the rate of dark recombination which takes place in Rhodobacter sphaeroides reaction centers between a primary quinone (Q(A)) and a bacteriochlorophyll dimer. Taking the energy of interaction between hydrogen bond protons and an excessive electron into account, we described qualitative by this nonmonotonous dependence. We considered a molecular model of the primary quinone from Rb. sphaeroides reaction centers. In addition to the primary quinone, the model includes two reaction center fragments that form hydrogen bonds with Q(A). One of these fragments is His(M219), and the other is the peptide [Asn(M259) - Ala(M260)]. We used the two-center approach with regard for electron-phonon interaction in order to calculate the characteristic time of electron tunneling during the recombination reaction. The energy of the phonon emitted/absorbed during the electron tunneling is determined by a relative shift of the donor and the acceptor energy levels, the detuning of levels. The value of level detuning was shown to be temperature dependent in a nonmonotonous manner in the case of hydrogen bonds with double-well potential energy surface. The characteristic time (or the reaction rate) depends on temperature parametrically. The dependence is nonmonotonous and is in qualitative agreement with the experimental one.
Krasil'nikov
P M
PM
Mamonov
P A
PA
Noks
P P
PP
Rubin
A B
AB
D004151:Dipeptides / Q000378:metabolism; D004579:Electron Transport; D006639:Histidine / Q000378:metabolism; D006860:Hydrogen Bonding; D008954:Models, Biological; D045322:Photosynthetic Reaction Center Complex Proteins / Q000502:physiology*; D011522:Protons; D011809:Quinones / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000502:physiology*; D013696:Temperature
D004151:Dipeptides; D045322:Photosynthetic Reaction Center Complex Proteins; D011522:Protons; D011809:Quinones; D006639:Histidine