title: Evidence for two types of P-700 in membrane fragments from a blue-green alga.
abstract: The mathematical analysis described in the preceding paper (Biochim. Biophys. Acta (1977) 460, 65-75), in which the steady-state photooxidation of P-700 was compared with overall electron flux in Photosystem I chloroplast fragments, was applied to membrane fragments from the blue-gree alga Nostoc muscorum (Strain 7119) noted for their high activity of both Photosystem I and Photosystem II. The same analysis, which gave good agreement between the photooxidation of P-700 and the overall light-induced electron flux (measured as NADP+ reduction) in Photosystem I chloroplast fragments, revealed in the algal membrane fragments two P-700 components: one responding to high light intensity (P-700 HI), the photooxidation of which was in good agreement with the overall electron flux (measured as NADP+ reduction by reduced 2,6-dichlorophenolindophenol), and the other component responding to low light intensity (P-700 LI), the photooxidation of which was not correlated with the reduction of NADP+ by reduced 2,6-dichlorophenolindophenol.
mesh_terms: D015086:2,6-Dichloroindophenol / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D000458:Cyanobacteria / Q000187:drug effects / Q000378:metabolism*; D003580:Cytochromes / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008027:Light; D008433:Mathematics; D010084:Oxidation-Reduction; D013053:Spectrophotometry
chemical_list: D003580:Cytochromes; D015086:2,6-Dichloroindophenol