Electron transport pathways in spinach chloroplasts. Reduction of the primary acceptor of Photosystem II by reduced nicotinamide adenine dinucleotide phosphate in the dark |
| |
Authors: | John D Mills David Crowther Rudolf E Slovacek Geoffrey Hind Richard E McCarty |
| |
Institution: | Biology Department, Brookhaven National Laboratory, Upton, NY 11973 U.S.A. |
| |
Abstract: | Addition of NADPH to osmotically lysed spinach chloroplasts results in a reduction of the primary acceptor (Q) of Photosystem II. This reduction of Q reaches a maximum of 50% in chloroplasts maintained under weak illumination and requires added ferredoxin and Mg2+. The reaction is inhibited by (i) an antibody to ferredoxin-NADP+ reductase (EC 1.6.7.1), (ii) treatment of chloroplasts with N-ethylmaleimide in the presence of NADPH, (iii) disulfodisalicylidenepropanediamine, (iv) antimycin, and (v) acceptors of non-cyclic electron transport. Uncouplers of phosphorylation do not affect NADPH-driven reduction of Q.It is proposed that electron flow from NADPH to Q may occur in the dark by a pathway utilising portions of the normal cyclic and non-cyclic electron carrier sequences. The possible in vivo role for such a pathway in redox poising of cyclic electron transport and hence in controlling the ATP/NADPH supply ratio is discussed. |
| |
Keywords: | Antimycin A Chloroplast Cyclic electron flow Electron transport Ferredoxin Fluorescence yield sulfo-DSPD disulfodisalicylidenepropanediamine Tricine MalNEt PS I Photosystem I PS II Photosystem II |
本文献已被 ScienceDirect 等数据库收录! |