Characteristics of a cytochrome P-450-dependent fatty acid omega-2 hydroxylase from bacillus megaterium

Abstract

The fatty acid (omega-2) hydroxylase from Bacillus megaterium ATCC 14581 was examined with respect to some general enzymatic properties attributed to an intact complex isolated in a partially purified state. Hydroxylase specific activity was found to increase with increasing protein concentration in a manner consistent with a reversible association of the components in the complex. There was a substantial kinetic lag phase for palmitate hydroxylation which was abolished by a substrate preincubation in the absence of NADPH. The substrate bound and presumably activated the hydroxylase complex without the formation of a substrate-derived intermediated. The oxidation of NADPH and the hydroxylation of palmitate were found to occur in a one to one molar ration, independent of the protein concentration. Finally, a cytochrome P-450 component of the complex was identified on the basis of its CO-binding difference spectrum. It appears, that this cytochrome P-450 component is not identical to P-450 meg of the steroid hydroxylase system of B. megaterium ATCC 13368, since progesterone, an active substrate for the latter, is not hydroxylated by the preparation from B. megaterium ATCC 14581.