[Study of electron transport in the photosynthetic systems of higher plants by the ESR method. VI. Kinetics of photo-induced P700 redox transitions in a system of continuous and flash illumination of different duration].

The kinetics of P700 redox-transients in leaves and isolated been and spinach chloroplasts was studied by the ESR method. P700 oxidation after a short flash (less than 10 microseconds) of white light was not resolved. P700 oxidation may be resolved only after "long" (more than 500 microseconds) flash of red light (700 or 720 nm) with a slow reduction of P700+ in the dark. In case of 500 microseconds flash exciting both photosystems (600 nm) P700 response was not observed. Fast P700+ reduction was observed if the short pulse of white light was given simultaneously with a continuous background 707 nm light. We can conclude from these data that P700+ accepts an electron from its primary donor within 10--500 microseconds.