A salt-inhibited cytochrome c reductase obtained from the moderately halophilic bacterium, Micrococcus halodenitrificans.

A membrane-bound cytochrome c reductase from Micrococcus halodenitrificans was inhibited by NaCl at concentrations as low as 0.05 m. The inhibition was competitive with respect to cytochrome c and noncompetitive with respect to reduced nicotinamide adenine dinucleotide. Thus the effect of NaCl was to increase the apparent K(m) of the enzyme for cytochrome c and not to inhibit the intrinsic activity of the enzyme.