Photoaffinity labeling of the phylloquinone‐binding polypeptides by 2‐azidoanthraquinone in photosystem I particles

[摘要]

A photoaffinity label, 2-azido-9,10-anthraquinone, binds at the quinone-binding (Q_φ) 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_φ site is located on psaA or psaB polypeptides.

[学科分类] 生物化学/生物物理

[关键词] Photosystem I;Reaction center;Photoaffinity label;Phylloquinone (vitamin K1);Electron transfer;AzAQ;2-azido-9;10-anthraquinone;CBB;Coomassie brilliant blue;LDAO;lauryldimethylamine oxide;P700;the primary donor chlorophyll a;PS;photosystem;Qφ;the secondary acceptor quinone;RC;reaction center;SDS;sodium dodecyl sulfate;PAGE;polyacrylamide gel electrophoresis