High and low potential states of the chloroplast cytochrome b-559 and thermodynamic control of non-cyclic electron transport.

Abstract

Most of the chloroplastb-559 is high potential at neutral pH as defined by hydroquinone reducibility. FCCP* (20 μM) and antimycin A (50 μM) convert high potentialb-559 to a low potential state which can be reduced by ascorbate but not hydroquinone. The low and high potential states of cytochromeb-559 are different forms of the same cytochrome.