The rates of proton uptake and electron transfer at the reducing side of photosystem II in thylakoids.
Proton and electron transfer at the reducing side of photosystem II of green plants was studied under flashing light, the former at improved time resolution by using Neutral red. The rates of electron transfer within QAFeQB were determined by pump-probe flashes through electrochromic transients. The extent of proton binding was about 1 H+/e-. The rates of proton transfer were proportional to the concentration of Neutral red (collisional transfer), whereas the rates of electron transfer out of QA- and from QAFeQB- to the cytochrome b6f complex were constant. The half-rise times of electron transfer (tau e) and the apparent times of proton binding (tau h) at 30 microM Neutral red were: QA- --> FeIIIQB (tau c < or = 100 microseconds, tau h = 230 microseconds); QA- --> FeIIQB (tau c = 150 microseconds, tau h = 760 microseconds); and QA- --> FeIIQB (tau c = 150 microseconds, tau h = 760 microseconds); and QA- --> FeIIQB (tau c = 620 microseconds, tau h = 310 microseconds).
Haumann
M
M
Biophysik, FB Biologie/Chemie, Universität Osnabrück, Germany.
Junge
W
W
D000222:Adaptation, Physiological; D001692:Biological Transport; D002736:Chloroplasts / Q000378:metabolism* / Q000528:radiation effects; D003624:Darkness; D004579:Electron Transport; D007887:Fabaceae; D007425:Intracellular Membranes / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D009499:Neutral Red / Q000378:metabolism; D010084:Oxidation-Reduction; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism* / Q000528:radiation effects; D045332:Photosystem II Protein Complex; D010946:Plants, Medicinal; D011522:Protons; D013053:Spectrophotometry / Q000379:methods; D013997:Time Factors
D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011522:Protons; D009499:Neutral Red