EFFECT OF LOW COPPER CONCENTRATIONS ON PHOTOSYSTEM-II PHOTOINHIBITIONIN CHLORELLA-VULGARIS

Cu2+-induced inactivation of photosystem II reaction centers at low io n concentrations was studied in Chlorella vulgaris Beijer. Within a co ncentration range of 5 - 100 mug/l, Cu2+ provoked photoinhibition of p hotosystem II in the light. In darkness, Cu2+ inactivated photosystem Il at concentrations exceeding 50 mug/l. Photosystem II inactivation a nd recovery kinetics at different light intensities in the presence of Cu2+ showed that retardation of the recovery process, which is suppos edly concerned with the synthesis of the D1-protein of photosystem II, is predominantly responsible for the decrease in photosystem Il activ ity in the light.