Phylloquinone copurifies with the large subunit of photosystem I

AbstractPhotosystem I preparations from the cyanobacterium Anabaenavariabilis and from spinach were analyzed for their quinone content. The dominant quinone was identified as phylloquinone. It was present at a ratio of roughly 2 per P700 (the primary electron donor of photosystem I) both in particles prepared with Triton X-100 and on the large, P700-carrying subunit derived from these particles by treatment with SDS. The results suggest a function of phylloquinone in the reaction center