Cytochrom-b-563 als natürlicher Elektronenüberträger in einem zyklischen Elektronentransport der Photosynthese

Abstract

By excitation of spinach chloroplasts with flashes (5 · 10^-5 sec) of far red light hvI (λ=728 nm) and with addition of 2·10^-4M/I benzylviologen as electron acceptor irreversible absorption changes are observed as depicted in fig. 1 top. With 10^-3 M/l K₃Fe (CN)₆ as electron acceptor irreversible changes are observed as depicted in fig. 1 bottom. The difference of the spectra in fig. 1 is presented in fig. 2. Fig. 2 corresponds to the spectrum which is caused by reduction of a cytochrome-b-563. Thus excluding K₃Fe (CN)₆ as electron acceptor cytochrome-b-563 can be reduced by hvI (λ=728 nm). A re-oxydation occurs by red light hvII (λ = 663 nm), s. figs. 3, 4. These results demonstrate a natural cyclic flow of electrons including both light reactions Chl-ai and Chl-aII (s. fig. 6). The results are reviewed in 1. c.¹⁰.