An oxygen-evolving complex with a simple subunit structure - ‘a water-plastoquinone oxidoreductase” - from the thermophilic cyanobacterium Synechococcus sp.

Abstract An oxygen-evolving complex has been highly purified from the thermophilic cyanobacterium Synechococcus sp. 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 Q A , had an oxygen-evolving activity of 300–400 μmol mg chl per h in the presence of 5 mM MnCl 2 ; or CaCl 2 . The complex most likely represents a minimum functional unit of the photosynthetic oxygen evolution.