On the mechanism of adenylyl sulfate reductase for the sulfate-reducing bacterium, Desulfovibrio vulgaris.

NADH dehydrogenases have been isolated in a low-molecular weight form (56,500) from both low-iron and normal-iron grown cells of Azotobacter vinelandii. Unlike low-molecular weight forms of NADH dehydrogenases reported from mammalian mitchondria, the enzymes in this study have not undergone any unusual alterations in various reactivities with substrates and electron acceptors. The NADH dehydrogenases from A. vinelandii do differ in cofactor cotent, light-absorption spectra and electron paramagnetic resonance spectra but show similar catalytic-center activities with substrates and electron acceptors. The relationship of these NADH dehydrogenases to site I oxidative phosphorylation in both the bacterial and mammalian systems is discussed.