The cytochromeb559 content was examined in five types of isolated photosystem II D1-D2-cytochromeb559reaction center preparations containing either five or six chlorophylls per reaction center. The reaction center complexes were obtained following isolation procedures that differed in chromatographic column material, washing buffer compo-sition and detergent concentration. Two different types of cytochromeb559assays were performed. The absolute heme content ineachpreparationwas obtainedusing theoxidized-minus-reduced difference extinction coefficient of cyto-chrome b559 at 559 nm. .
