title: Effect of pyrophosphate on photosynthetic electron transport reactions.
abstract: Inorganic pyrophosphate is found to inhibit the ferredoxin-dependent photoreduction of NADP by isolated chloroplasts. The reduction of ferricyanide is not inhibited, nor is the activity of photosystem 1 as measured with methyl viologen as the electron acceptor. All other ferredoxin-depended reactions are inhibited, such as cytochrome c photoreduction and the reaction sequence: NADPH -->Flavoprotein-->ferredoxin-->cytochrome c. The inhibition by pyrophosphate is, in all cases, competitive with ferredoxin and independent of NADP concentration. Pyrophosphate inhibition of the formation of the ferredoxin-flavoprotein complex is demonstrated spectrophotometrically.
authors.affiliation: Laboratory of Plant Physiology, Istituto Botanico dell'Universita Via Amendola 175, Bari, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Forti
authors.forename: E M
authors.initials: EM
authors.lastname: Meyer