The relationship between P-680 and C-550.
The published reports of flash-induced absorbance changes in the 680-690 nm spectral region, which have been attributed to bleaching of the primary reaction center chlorophyll of photosystem II (PSII) P-680, are discussed in light of what is known about the primary electron acceptor of PSII, C-550. The question of whether the fluorescence yield changes, which accompany the photoreduction of C-550, might influence the measurements of chlorophyll bleaching is examined. The responses attributed to P-680 and their relationship to C-550 indicate that, if the absorbance measurements are valid, P-680 probably functions as the primary electron donor to PSII rather than as a photochemical sensitizer of the primary redox reaction.
D000473:Alkanes; D002734:Chlorophyll / Q000528:radiation effects; D002736:Chloroplasts / Q000032:analysis; D004237:Diuron / Q000494:pharmacology; D004579:Electron Transport; D005453:Fluorescence; D006358:Hot Temperature; D010084:Oxidation-Reduction; D010777:Photochemistry; D011830:Radiation Effects; D013053:Spectrophotometry
D000473:Alkanes; D002734:Chlorophyll; D004237:Diuron