Abstract
The major Chlamydomonas reinhardi y-1 chloroplast membrane polypeptides-I + II, IV, V(a + b)-have been isolated by use of preparative sodium dodecyl sulfate-gel electrophoresis.Rabbit antisera prepared against these polypeptides interact with intact membranes as well as membrane fractions containing these specific antigens. Antisera against polypeptides I + II partially inactivate photosystem I. Antisera against polypeptide IV prevent inactivation of the Hill reaction and inhibit photooxidation of diphenylcarbazide with dichlorophenolindophenol as an electron acceptor. The protection of the Hill reaction by IV antiserum, measured with whole membranes, is partially hindered by the presence of V antiserum, which, by itself, causes inhibition of diphenylcarbazide photooxidation.We concluded that parts of the primary structure of these polypeptides are exposed in situ and can be recognized in whole membranes by antisera prepared against sodium dodecyl sulfate-denatured antigens. Polypeptides I and II, and polypeptides IV, Va, and Vb are associated with photosystem I and photosystem II, respectively.