Cytochrome f and plastocyanin kinetics in Chlorella pyrenoidosa. I. Oxidation kinetics after a flash.
P-700, plastocyanin and cytochrome f redox kinetics were measured after one flash, using dark-adapted Chlorella in the presence of hydroxylamine and 3(3,4-dichlorophenyl)-1,1-dimethylurea. Plastocyanin becomes increasingly oxidized with a half-time of 70 microseconds, then undergoes reduction with a half-time of 7ms. Cytochrome f oxidation has a sigmoidal time-course and a half-time of 100 microseconds. Its redution exhibits a half-time of 4 ms. These results are interpreted in a linear scheme: (formula: see text). An equilibrium constant of 2 between cytochrome f and plastocyanin (PC), which contrasts with the large equilibrium constant between PC and P-700 is computed. The presence of cytochrome b6 in a cyclic path around Photosystem I is confirmed under these conditions.
D002708:Chlorella / Q000378:metabolism*; D003580:Cytochromes / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D010788:Photosynthesis; D010940:Plant Proteins / Q000378:metabolism*; D010970:Plastocyanin / Q000378:metabolism*; D013057:Spectrum Analysis
D003580:Cytochromes; D010940:Plant Proteins; D010970:Plastocyanin