Observation of One Pheophytin a Molecule Not Associated with Primary Photochemistry in the Isolated Photosystem Ⅱ Reaction Center D1/D2/Cyt b559 Complex
Abstract:Photodamage of pheophytin a (pheo a) in the isolated photosystem Ⅱ (PSⅡ ) reaction center D1/D2/Cyt b559 complex from spinach has been investigated by high performance liquid chromatographic method in detail. The results showed that: (1) There is one pheo a molecule which is not associated with the primary photochemistry in the PS Ⅱ reaction center complex. It may be considered that there are two different electron transfer branches in the PS Ⅱ reaction center just as in the purple bacterium photosynthetic reaction center. (2) The damaged pheo a may be attributed to the one bonding to the D2 protein comparing the D2 subunit in the PS Ⅱ reaction center with M subunit in the purple bacterium photosynthetic reaction center. (3) A possible arrangement model of redox cofactors in the PS Ⅱ reaction center was proposed based on our experiment.