Title: A comparative study of photosynthetic electron transport in algal cells and spinach chloroplasts
Abstract: Steady-state relaxation spectroscopy provides absorption data which may be used to calculate the rates of electron flow through intermediates of the electron transport chain. In chloroplasts, the calculated rates for P700 agree well with measured Hill reaction velocities. The relaxation times of cytochrome and P700 are consistent with current theories of sequential electron transport from cytochrome to P700 in chloroplasts, but not in whole cells of a red and of a blue-green alga. 3-(3,4-Dichlorophenyl)-1, 1-dimethylurea (DCMU) inhibits all activity in chloroplasts while in intact cells electron transport through P700 and cytochrome continues even at a concentration of the inhibitor which eliminates O2 evolution. With 620-nm light, the amplitude of oxidized cytochrome increases upon addition of DCMU partly because its reduction rate declines and partly because quanta are diverted from Photosystem II to Photosystem I. Relaxation times also increase, but this increase can be reversed by further addition of the uncoupler carbonyl cyanide m-chlorophenylhydrazone.
Publication Year: 1970
Publication Date: 1970-05-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 24
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