Isolation and partial characterization of a very long-chain fatty acid desaturation system from the cytosol of Mycobacterium smegmatis.

The supernatant fraction after 105,000 X g centrifugation of an extract of sonically disrupted cells of Mycobacterium smegmatis catalyzed the desaturation of lignoceroyl-CoA to a delta15-monounsaturated derivative in the presence of molecular oxygen and NADPH. This desaturation system was separated by ammonium sulfate fractionation, gel filtration, DEAE-cellulose column chromatographies, and affinity column chromatography on immobilized dye, into three components; a NADPH-oxidase, a ferredoxin-containing fraction and a desaturase, all of which were required for the reconstituted desaturation system for lignoceroyl-CoA. This system was inhibited by FMN and ferrous ions but not by KCN. All of these features clearly distinguish this system from the previously known fatty acid desaturation systems of various origins.