Purification, characterization and properties of an NADH oxidase from Desulfovibrio vulgaris (Hildenborough) and its coupling to adenylyl phosphosulfate reductase.

An NADH oxidase was purified from Desulfovibrio vulgaris. This FMN-containing enzyme reacts with oxygen forming hydrogen peroxide with a specific activity of 0.21 mumoles.min-1.mg-1. The molecular weight of the protein was determined to be 65 kDa on 12.5% SDS/PAGE. It shows very low NADH: rubredoxin oxidoreductase activity specifically towards the rubredoxin from the same organism. However, adenylyl phosphosulfate reductase can be fully reduced by NADH with the purified enzyme, suggesting that NADH could be an electron donor for respiratory sulfate reduction.