Iwaki M, Takahashi M, Shimada K, Takahashi Y, Itoh S
Division of Bioenergetics, National Institute for Basic Biology, Okazaki, Japan.
FEBS Lett. 1992 Nov 2;312(1):27-30. doi: 10.1016/0014-5793(92)81403-9.
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.
