Thermoluminescence study of charge recombination in Photosystem II at low temperatures. II. Oscillatory properties of the Zv and A thermoluminescence bands in chloroplasts dark-adapted for various time periods

摘要: The oscillations of the ZV and A thermoluminescence bands were investigated in spinach chloroplasts which had been dark-adapted for various time periods subjected to a series flashes at +2°C before continuous illumination low temperatures. When excited with light below −65°C, band exhibited period-4 oscillation, maxima on preflashes 0, 4 8. Above oscillation pattern depended greatly dark-adaptation period chloroplasts. In preilluminated samples (15 s followed by 3 min dark), when QB pool is half oxidized, intensity measured −50°C was similar that observed −65°C. However, after thorough (6 h), major fraction assumed be binary appeared pattern, odd flash numbers. Below period-2 could not induced chloroplasts, suggesting an inhibition electron exchange between QA QB. Upon excitation −30°C, oscillated periodicity preflash numbers 2 6. At pH 7.5, converted into (24 h). Model calculations oscillatory patterns suggest are determined concentrations [S0] + [S1] [S2] [S3], respectively, present prior low-temperature illumination. amplitudes reflect changes occurring redox state sequence flashes. possible relationship characteristics temperature-dependence S transitions investigated. Comparison amplitudal B (S2Q−B S3Q−B recombination) Q (S2Q−A as function temperature suggests S2 → S3 S4 blocked about −65 −40°C, respectively. It also concluded emitted reaction center twice high state.