Site-specific inhibition of photophosphorylation in isolated spinach chloroplasts by HgCL2. II. Evidence for three sites of energy conservation associated with non-cyclic electron transport.

Energy transfer inhibition by HgCl2 has been demonstrated to be selective for certain System I partial reactions. On the basis of different HgCl2 effects on the System I reactions, reduced 2,6-dichlorophenolindophenol --> methylviologen, diaminodurene --> methylviologen and N-phenazine methosulfate cyclic, two sites of energy conservation associated with System I are proposed. Furthermore, these sites are in parallel with each other, in series with the site closely associated with Photosystem II and are shared between non-cyclic and cyclic electron transport.