Photoaffinity labeling of the phylloquinone-binding polypeptides by 2-azidoanthraquinone in photosystem I particles.
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.
Iwaki
M
M
Division of Bioenergetics, National Institute for Basic Biology, Okazaki, Japan.
Takahashi
M
M
Shimada
K
K
Takahashi
Y
Y
Itoh
S
S
D000345:Affinity Labels / Q000378:metabolism*; D000880:Anthraquinones / Q000378:metabolism*; D001386:Azides / Q000378:metabolism*; D001665:Binding Sites; D002736:Chloroplasts / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D045322:Photosynthetic Reaction Center Complex Proteins / Q000302:isolation & purification / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D010944:Plants / Q000378:metabolism*; D013053:Spectrophotometry; D010837:Vitamin K 1 / Q000378:metabolism*
D000345:Affinity Labels; D000880:Anthraquinones; D001386:Azides; D010446:Peptide Fragments; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; C051914:2-azidoanthraquinone; D010837:Vitamin K 1