Application

Cholesterol oxidase has been used in a study to improve treatment of oxysterol-mediated cytotoxicity. Cholesterol oxidase has also been used in a study that evaluated the effects of cholesterol depletion. This study reported that cholesterol depletion impairs the coupling between channel opening and vesicle release. Additionally, cholesterol oxidase is used to determine serum cholesterol levels. The enzyme also finds application in the microanalysis of steroids in food samples. It has also been used for distinguishing 3-ketosteroids from 3β-hydroxysteroids. Transgenic plants expressing cholesterol oxidase have been investigated in the fight against the cotton boll weevil. CHOD has also been used as a molecular probe to elucidate cellular membrane structures.

Cholesterol oxidase has been used in a study to improve treatment of oxysterol-mediated cytotoxicity. Cholesterol oxidase has also been used in a study that determined that cholesterol depletion impairs coupling between channel opening and vesicle release by allowing voltage-gated calcium channels to move further from release sites.

Biochem/physiol Actions

Cholesterol oxidase (CHOD) is a monomeric flavoprotein containing FAD that catalyzes the first step in cholesterol catabolism. This bifunctional enzyme oxidizes cholesterol to cholest-5-en-3-one in an FAD-requiring step. The pH optimum of the enzyme is 7.0 to 7.5 and temperature optimum is 50 °C. The pH stability is 5.7-7.8. Hg²⁺, Ag⁺, and ionic detergents inhibit the enzyme activity. Molecular mass of the enzyme is 62 kDa. Pathogenic bacteria require CHOD to infect a host′s macrophage.

Preparation Note

CHOD is soluble in cold 50 mM potassium phosphate buffer, pH 7.0. Prepare solutions immediately before use.

Unit Definition

One unit will convert 1.0 µmole of cholesterol to 4-cholesten-3-one per min at pH 7.5 at 25 °C. Note: 4-cholesten-3-one may undergo isomerization.