ESTIMATING THE EFFECT OF PROTEIN DYNAMICS ON ELECTRON-TRANSFER TO THESPECIAL PAIR IN THE PHOTOSYNTHETIC REACTION-CENTER

The importance of dynamical fluctuations on the tunneling matrix eleme nt of electron transfer has been probed using the Pathway model. The e ffect of fluctuations of atoms was estimated by optimizing their thoug h-space coupling, thus mimicking the effect of real dynamics. Applicat ion of this simple model to the electron transfer between cytochrome c 2 and photosynthetic reaction center shows that atomic motion could in crease the overall intermolecular electronic coupling by over one orde r of magnitude. These results indicate that, for this system, thermal fluctuations are necessary to obtain the fast inter-protein unimolecul ar electron transfer rate (around 1 mu s.) (C) 1997 Published by Elsev ier Science B.V.