Studies On Effect Of Phosphatidylglycerol On Oxygen-evolving Activity In Photosystem Ⅱ

The effects of PG on Oxygen evolving activity in PSII were studied by methods of Biochemistry and Biophysics. First the pure PSII particles were prepared from spinach, which were determined by the techniques of SDS-PAGE and Low temperature (77K) fluorescence spectrum. Then we digested PSU with PLA2, we have got the following results by reconsititution and depletion of PG on PSII: 1) PG have played the important role on the functions of PSII. The PSII would lose the activity without the existence of PG. And the PSII particles without treatment of PLA2 kept the stable oxygen evolving activity when the temperature was between 20C and 30 C. In addition, we found the oxygen evolving activity towed with the increasement of temperature from 35C. While the PSII treated with PLA2 had no activity measured. 2)The experiments showed that the oxygen evolving activity of PSII particles was affected upon incubation with PG Iiposome; that is, there is a stimulation of oxygen evolution at low concentration of PG/Chl (mg/mg), whereas at higher values of this ratio an inhibition is observed. 3)The membrane lipids constitution of CP43 is MGDG, and that of the CP47 are MGDG and PG.