Cholesterol Oxidase (CHOD)

Cholesterol oxidase is an alcohol dehydrogenase/oxidase flavoprotein that catalyzes the dehydrogenation of C(3)-OH of a cholestane system to yield the corresponding carbonyl product. During the reductive half-reaction, the oxidized FAD cofactor accepts a hydride from the substrate and in the ensuing oxidative half-reaction, the reduced flavin transfers the redox equivalents to molecular oxygen yielding hydrogen peroxide. Interestingly, CO also catalyzes the isomerization of cholest-5-en-3-one (the product of the redox reaction) to cholest-4-en-3-one. CO has been proposed as a virulence factor playing a role in infections caused by the pathogen bacterium Rhodococcus equi. Since this enzymatic activity is unique to bacteria, it may represent a novel molecular target for antibiotic discovery. CO also acts as signaling protein for the biosynthesis of polyene macrolide pimaricin in Streptomyces natalensis.