FEBS Letters | |
Electrons generated by photosystem II are utilized by an oxidase in the absence of photosystem I in the cyanobacterium Synechocystis sp. PCC 6803 | |
Vermaas, Wim F.J.1  Styling, Stenbjörn1  Shen, Gaozhong2  | |
[1] Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden;Department of Botany and Center for the Study of Early Events in Photosynthesis, Arizona State University, Tempe, AZ 85287-1601, USA | |
关键词: Thylakoid membrane; Photosynthesis; Electron transport; Plastoquinone; Respiration; KCN-sensitive oxidase; DCMU; 3-(3; 4-dichlorophenyl)-1; 1-dimethylurea; DMBQ; 2; 6-dimethyl-p benzoquinone; F o; prompt fluorescence; F v; variable fluorescence; HEPES; 4-(2-hydroxyethyl)-1-piperazineethane-sulfonic acid; PS I; photosystem I; PS II; photosystem II; QA; the first quinone-type electron acceptor in photosystem II; | |
DOI : 10.1016/0014-5793(94)80638-1 | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
【 摘 要 】
The reduction and reoxidation kinetics of the first quinone-type electron acceptor in photosystem II, QA −, were measured by fluorescence in a light-tolerant, photosystem I-less strain of the cyanobacterium Synechocystis sp. PCC 6803. In this strain, which shows excellent amplitudes of variable fluorescence, the rate of QA − oxidation after photoreduction of the plastoquinone pool was about half of that in the presence of photosystem I. However, upon addition of 5 mM KCN, QA − decay was very slow, and the rate was comparable to that seen in the presence of diuron, which blocks electron transport between QA and QB. The KCN-imposed block of QA − oxidation was removed efficiently by addition of exogenous quinones that can oxidize the plastoquinone pool. These results indicate that, in the absence of photosystem I, photosystem II-generated electrons are used very effectively by an oxidase located in the thylakoid; this oxidase may be a component of the respiratory chain.
【 授权许可】
Unknown
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