The role of cytochrome b559 in photosynthetic

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The role of cytochrome b559 in photosynthetic

The role of cytochrome
b559 in photosynthetic oxygen evolution has been investigated in three chloroplast mutantsChlamydomonas reinhardtii, in which one of the two histidine axial ligands to the heme, provided by the

subunit, has been replaced by the residues methionine, tyrosine, and glutamine. Photosystem two complexes







functional for oxygen evolution could be assembled in the methionine and tyrosine mutants up to

of wild type levels, whereas no complexes with oxygen evolution activity could be detected in the glutamine
mutant. PSII supercomplexes isolated from the tyrosine and methionine mutants were as active as wild type in
terms of light-saturated rates of oxygen evolution but in contrast to wild type contained no bound heme despite
the presence of the