Spectroelectrochemistry of P700 in native photosystem I particles and diethyl ether-treated thylakoid membranes from spinach and Thermosynechococcus elongatus
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
Abstract:
The redox potentials (E(composite function')) of P700 in intact and diethyl ether-treated thylakoid membranes as well as native photosystem (PS) I particles from spinach and Thermosynechococcus elongatus have been measured by a spectroelectrochemistry with an error range of +/-2-3 mV. Stepwise removal of antenna pigments by ether treatment caused distinct shifts of the E( composite function') value with increasing degree of water saturation in ether; negatively from +471 to +428 mV for spinach, but positively from +423 to +436 mV for T. elongatus. Such a contrasting behavior is discussed by invoking the mode of action of ether on the microenvironments around P700.