Presence of Polypeptides of Cytoplasmic and Chloroplastic Origin in Isolated Photoactive Preparations of Photosystems I and II in Chlamydomonas reinhardi y-1

Abstract

Photoactive preparations were obtained by treatment of photosynthetic membranes with lipid micelles and deoxycholate.A photosystem I preparation can be extracted from the membranes by both lipid micelles and deoxycholate, whereas the photosystem II preparation remains in a particulate state.The photosystem II preparation exhibits electron transfer activity measured by photoreduction of 2,6-dichlorophenolindophenol with 1,5-diphenylcarbazide as an electron donor and has a ratio of chlorophyll a/b of 1.4. This preparation contains three major polypeptides of cytoplasmic origin and two of chloroplastic origin.The photosystem I preparation exhibits high rates of methylviologen photoreduction with ascorbate and 2,6-dichlorophenolindophenol as electron donors and does not contain chlorophyll b. This preparation contains two major polypeptides of chloroplastic origin and one of cytoplasmic origin. These results indicate that both cytoplasm and chloroplast contribute polypeptides for the formation of photosystems I and II in Chlamydomonas reinhardi.