Quantitative analysis of membrane components in a highly active O2-evolving photosystem II preparation from spinach chloroplasts |
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Authors: | Yasusi Yamamoto Kenichi Tabata Yasuhiro Isogai Mitsuo Nishimura Shigeki Okayama Katsumi Matsuura Shigeru Itoh |
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Affiliation: | a Department of Biology, Faculty of Science, Kyushu University, Fukuoka 812, Japan b Laboratory of Biology, College of General Education, Kyushu University, Fukuoka 810, Japan c National Institute for Basic Biology, Okazaki 444, Japan |
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Abstract: | Stoichiometry of membrane components associated with Photosystem II was determined in a highly active O2-evolving Photosystem II preparation isolated from spinach chloroplasts by the treatment with digitonin and Triton X-100. From the analysis with sodium dodecyl sulfate polyacrylamide gel electrophoresis and Triton X-114 phase partitioning, the preparation was shown to contain the reaction center protein (43 kDa), the light-harvesting chlorophyll-protein complex (the main band, 27 kDa), the herbicide-binding protein (32 kDa) and cytochrome b-559 (10 kDa) as hydrophobic proteins, and three proteins (33, 24 and 18 kDa) which probably constitute the O2-evolution enzyme complex as hydrophilic proteins. These proteins were associated stoichiometrically with the Photosystem II reaction center: one Photosystem II reaction center, approx. 200 chlorophyll, one high-potential form of cytochrome b-559, one low-potential form of cytochrome b-559, one 33 kDa protein, one (to two) 24 kDa protein and one (to two) 18 kDa protein. Measurement of fluorescence induction showed the presence of three electron equivalents in the electron acceptor pool on the reducing side of Photosystem II in our preparation. Three molecules of plastoquinone A were detected per 200 chlorophyll molecules with high-performance liquid chromatography. The Photosystem II preparation contained four managanese atoms per 200 chlorophyll molecules. |
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Keywords: | Oxygen evolution Photosystem II (Spinach chloroplast) |
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