Cyclic photophosphorylation and electron transport

Evidence for two cyclic photophosphorylation reactions concurrent with ferredoxin-catalyzed non-cyclic electron transport

Addition of ferredoxin to isolated spinach chloroplast thylakoid membranes reconstitutes phosphorylating electron transfer characterized by elevated P / O ratios (1.6). When oxygen is the terminal electron acceptor for reduced ferredoxin, the P / O value is lowered by antimycin A or low concentrations (I0/~M) of heparin (an anionic macromolecule), but not by inhibition of the activity of membra...

Photophosphorylation Associated with Photosystem II: II. Effects of Electron Donors, Catalyst Oxidation, and Electron Transport Inhibitors on Photosystem II Cyclic Photophosphorylation.

Incubation of KCN-Hg-NH(2)OH-inhibited spinach (Spinacia oleracea L.) chloroplasts with p-phenylenediamine for 10 minutes in the dark prior to illumination produced rates of photosystem II cyclic photophosphorylation up to 2-fold greater than the rates obtained without incubation. Partial oxidation of p-phenylenediaine with ferricyanide produced a similar stimulation of ATP synthesis; addition ...

Interaction of Photophosphorylation and Electron Transport Systems in Bacterial Chromatophores.

Chromatophore fractions isolated from photosynthetic bacteria can catalyze light-dependent phosphorylation of adenosine diphosphate to triphosphate (l-3) and also a variety of lightactivated electron transfer reactions, including photoreduction and photo-oxidation of dyes and pyridine nucleotides (4, 5). Whether or not phosphorylation and such electron transport are independent, can occur simul...

Non cyclic photophosphorylation pdf

Regulation of Cyclic Photophosphorylation during Ferredoxin-Mediated Electron Transport : Effect of DCMU and the NADPH/NADP Ratio.

Addition of ferredoxin to isolated thylakoid membranes reconstitutes electron transport from water to NADP and to O(2) (the Mehler reaction). This electron flow is coupled to ATP synthesis, and both cyclic and noncyclic electron transport drive photophosphorylation. Under conditions where the NADPH/NADP(+) ratio is varied, the amount of ATP synthesis due to cyclic activity is also varied, as is...