Cholesterol Oxidase : Properties and Applications

Abstract

Cholesterol oxidase (CO) is a bifunctional flavoenzyme, which catalyzes the oxidation and isomerization of 3 β-hydroxy-5-ene-steroids to 3-keto-4-ene-steroids. CO is produced by a variety of soil microorganisms such as Brebivacterium, Nocardia, Psuedomonas, Rhodococcus and Streptomyces sp., and is becoming an increasingly important and widely used material in various industrial fields. CO is now an important ingredient in most commercially available assay kits for serum cholesterol screening.CO has a broad range of substrate specificity towards various 3 β-hydroxy-steroids and potential applications as catalyst in organic synthesis since it is stable in the presence of water-immiscible solvents at high concentrations, thus making possible the conversion of water-insoluble substrates. The enzyme shows excellent regio-, stereo-, and enantio-selectivity in the oxidation of non-steroidal compounds. But despite these features and the three-dimensional structure of CO from B. sterolicum, the catalytic mechanisms of this class of enzymes are little understood.CO has insecticidal activity against insects like boll weevil larvae and expression of the CO gene in plant cells has been studied to find means for producing genetically modified plants for pest control. Expression of the gene in Lactobacillus sp. has been studied to control cholesterol levels in fermented dairy foods.