Arieli, B., Hauska, G., Herrmann, I. and Padan, E.

Sulfide-quinone reductase (SQR) is a membranal electron carrier which catalyzes the initial step in sulfide-dependent anoxygenic photosynthesis in prokaryotes. We report here on the isolated and partially purified SQR of the cyanobacterium Oscillatoria limnetica. The functional enzyme is a quinone-binding protein which is probably composed of a single polypeptide, having an apparent molecular weight (on SDS-PAGE) of 57 KDa. SQR was also isolated from the bacteria Rhodobacter capsulatus and Chlorobium limicola f. thiosulfatophilum.