Do Cyanobacteria Contain a Membrane Bound Cysteine Oxidase?

The oxidation of cysteine with 0 is facilitated by isolated membranes of the cyanobacteria Anacystis nidulans and Anabaena variabilis, and further stimulated by Fe . This reaction accelerates with increasing the pH value and is suppressed by cyanide, benzylhydroxamate, hydroxylamine, but not azide. The agents mentioned inhibited the respiration of the membranes with ascorbate and N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) effectively, but did not influence their nonenzymic oxidation. It is inferred that ascorbate in combination with TMPD is oxidized via membrane oxidases. Cysteine oxidation apparently proceeds non-enzymatically and is catalyzed by the cations of heavy metals.