Interaction of plastocyanin with photosystem I: a chemical cross-linking study of the polypeptide that binds plastocyanin |
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Authors: | R M Wynn R Malkin |
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Institution: | Division of Molecular Plant Biology, University of California, Berkeley 94720. |
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Abstract: | Plastocyanin has been covalently cross-linked to photosystem I (PSI) by using a water-soluble cross-linker, N-ethyl-3-3-(dimethylamino)propyl]carbodiimide. The cross-linking reaction is light stimulated and results in the disappearance of a single 19-kDa subunit of PSI with the formation of a new protein-staining component of 31 kDa. The new product at 31 kDa reacts with both plastocyanin and 19-kDa subunit antibodies. Carboxyl group modified plastocyanin does not form a cross-linked product with PSI, implying that the negatively charged surface-exposed groups on plastocyanin are necessary to stabilize binding. These results demonstrate a specific interaction of plastocyanin with PSI and further implicate a specific protein to which plastocyanin binds to facilitate electron transfer to the P700 reaction center. |
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