Chlorophyll-Protein Complexes Associated with Photosystem I Isolated from the Green Alga, Bryopsis maxima

Six chlorophyll (Chl)-protein complexes associated with photosystemI (CPla), and the PS I reaction center complex (CPl) were isolatedfrom the thylakoid membranes of the green alga, Bryopsis maxima,by SDS-polyacrylamide gel electrophoresis. CPla had four polypeptides(22, 24, 25, 26 kDa) in addition to the 67 kDa polypeptide ofCPl. These complexes may thus possibly be a combination of CPland antenna complexes for PS I. Six CPla showed almost the sameoptical properties, with absorption maxima at 650 and 677 nmand contained carotene and a small amount of xanthophylls. TheChl a/b ratios of these CPla were about 2, while that of CPlwas 14. CPla showed a fluorescence emission maximum at 695 nm;its excitation spectrum had peaks at 438, 470 and 540 nm, correspondingto the absorption maxima of Chl a, Chl b, xanthophylls, respectively.An antenna complex free of CPl has been detected in some plantsbut was not found in the present alga. ¹Present address: Department of Botany, The University of Adelaide,Adelaide, S.A. 5001, Australia (Received April 17, 1986; Accepted June 26, 1986)