Abstract
A photoaffinity label, 2-azido-9,10-anthraquinone, binds at the quinone-binding (Q phi) site with high affinity and can substitute for the secondary acceptor, phylloquinone, in photosystem I reaction center of spinach. Phylloquinone-depleted photosystem I particles reconstituted with azido[3H]anthraquinone were illuminated with UV light and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The large core polypeptides (psaA and/or psaB) were selectively labeled. The labeling was competitively inhibited in the presence of anthraquinone. These results indicate that the Q phi site is located on psaA or psaB polypeptides.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Affinity Labels / metabolism*
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Anthraquinones / metabolism*
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Azides / metabolism*
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Binding Sites
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Chloroplasts / metabolism
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Electrophoresis, Polyacrylamide Gel
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Kinetics
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Molecular Weight
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Peptide Fragments / isolation & purification
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Photosynthetic Reaction Center Complex Proteins / isolation & purification
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Photosynthetic Reaction Center Complex Proteins / metabolism*
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Photosystem I Protein Complex
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Plants / metabolism*
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Spectrophotometry
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Vitamin K 1 / metabolism*
Substances
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Affinity Labels
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Anthraquinones
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Azides
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Peptide Fragments
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Photosynthetic Reaction Center Complex Proteins
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Photosystem I Protein Complex
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2-azidoanthraquinone
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Vitamin K 1