Abstract We have developed a simple and novel method to isolate a highly pure and active photosystem (PS) II complex, directly from thylakoid membranes. This complex is a discrete particle and contains all the proteins of the oxygen evolving complex and a set of chlorophyll a/b binding proteins. The intactness of both the donor side and the acceptor side has resulted in a very high oxygen evolution activity and therefore offers a superior experimental system to that of PSII enriched membrane fragments in which there is heterogeneity in activities and biochemical composition. z 1999 Federation of European Biochemical Societies
