KINETIC AND PHYSICAL PARAMETERS OF ELECTRON-TRANSFER IN PHOTOSYSTEM-1

A number of electron-transport models were used to make a kinetic anal ysis of experimental data for the structural complex of photosystem 1 (PS1) of higher plants. Rate constants were estimated for electron tra nsfer in the PS1 pigment-protein complex. Mechanisms of the interactio n of the latter with acceptors (iron-sulfur proteins) and the donor (p lastocyanin) were detailed. Two types of regulation of PS1-driven elec tron transfer were demonstrated: 1) light control of the activity of t he photosynthetic reaction center (RC) involving conformational rearra ngements and 2) interaction of the RC with mobile carriers. The change s in the electron transfer rate constants were studied for different f ragments as a function of temperature, viscosity, and ionic strength o f the medium.