A Single enzyme is Responsible for Both Dimethylsulfoxide and Trimethylamine-N-oxide Respirations as the Terminal Reductase in a Photodenitrifier: Rhodobacter sphaeroides f.s. denitrificans

Polyacrylamide gel electrophoresis of the periplasmic fractionfrom Rhodobacter sphaeroides f.s. denitrificans grown with dimethylsulfoxide(DMSO) and trimethylamine-Af-oxide (TMAO) showed that only onepolypeptide was stained for both DMSO and TMAO reductase activities,and it was the same as the purified DMSO redutase. Determinationof DMSO and TMAO reductase activities of intact cells grownwith DMSO or TMAO showed that each reagent induced both DMSOand TMAO activities and that DMSO showed much higher inductionactivity than TMAO. These results indicate that a single enzymeis responsible for both DMSO and TMAO respirations as the terminalreductase. (Received July 15, 1987; Accepted November 24, 1987)