Chlorophyll- and Heme-Binding Proteins in Porphyridium Cruentum Thylakoids

Abstract

Ch1-protein complexes (CP) can be isolated from thylakoids as detergent soluble complexes. In our studies on the relationships of PS I and PS II with the phycobilisomes, we have been isolating and characterizing the Ch1-protein complexes of P. cruentum. Previously (Redlinger, Gantt 1981a) we reported that this red alga contained three Ch1 a-protein complexes, but lacked CP II, the light harvesting Ch1 a/b protein complex. In the present study, we further characterize the Ch1-protein complexes and report that the major complex isolated is equivalent to CP I, and that two lesser complexes (CP III and IV) appear to be part of PS II. In addition we found four heme-binding proteins, which correspond to cytochromes typical of thylakoids.