PURIFICATION AND CHARACTERIZATION OF OXYGEN-EVOLVING PHOTOSYSTEM-II CORE COMPLEXES FROM THE GREEN-ALGA CHLAMYDOMONAS-REINHARDTII

Oxygen-evolving photosystem II complexes were isolated from the green alga Chlamydomonas reinhardtii by selective solubilization of thylakoi d membranes with dodecyl maltoside followed by density gradient centri fugation and anion-exchange chromatography. In the presence of CaCl2 a nd K-3[Fe(CN)(6)] the complexes evolved oxygen at rates exceeding 1000 mu mol (mg of chl)(-1) h(-1). The particles contained 40 chlorophylls a and had properties very similar to those of PSII isolated from high er plants. Chlamydomonas reinhardtii is now the first organism which c an be used for both site-directed mutagenesis and detailed biochemical and biophysical characterization of oxygen-evolving photosystem II. I t seems therefore to be an ideal model organism for investigation of s tructure-function relationships in photosynthetic oxygen evolution.