An oxygen‐evolving complex with a simple subunit structure ‐ ‘a water‐plastoquinone oxidoreductase” ‐ from the thermophilic cyanobacteriumSynechococcussp.

Abstract
An oxygen‐evolving complex has been highly purified from the thermophilic cyanobacteriumSynechococcussp. The complex, which reproducibly showed 5 major polypeptide bands of 47, 40, 35, 30 and 9 kDa on SDS‐polyacrylamide gel electrophoresis and contained 3.2 Mn per QA, had an oxygen‐evolving activity of 300–400chl per h in the presence of 5 mM MnCl2; or CaCl2. The complex most likely represents a minimum functional unit of the photosynthetic oxygen evolution.