Enzyme Activity Measurement for Cholesterol Oxidase

Creative Enzymes offers reliable and precise activity measurement for cholesterol oxidase, using spectrophotometric assays. We deliver the accurate assay results in the shortest span of time from the date of order placement, which distinguishes Creative Enzymes from our competitors.

Cholesterol oxidase (EC 1.1.3.6; COX) is a monomeric bi-functional FAD-containing microbial enzyme, which belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with oxygen as acceptor. The enzyme catalyzes three chemical conversations. In the first step which is called the reductive half-reaction, the 3β-hydroxyl group of the steroid ring system is oxidized to the corresponding ketone. FAD cofactor is the key to this reaction and becomes reduced in this process. In the second step, the enzyme catalyzes isomerization of the double bond in the oxidized steroid ring system from the Δ5-6 position to Δ4-5 position, to give the final steroid product, cholest-4-en-3-one. In the final step which is called the oxidative half-reaction, the reduced cofactor reacts with dioxygen and is reoxidized while O₂ is reduced to H₂O₂. The systematic name of this enzyme class is cholesterol:oxygen oxidoreductase, which is also known as cholesterol-O₂ oxidoreductase, 3beta-hydroxy steroid oxidoreductase, and 3beta-hydroxysteroid:oxygen oxidoreductase. Cholesterol oxidase was originally isolated and characterized from Rhodococcus erythropolis. Afterwards, it was also found to be produced by many bacteria, including both Gram-positive and Gram-negative, but the Actinomycetes come under the most prolific COX-group.

Cholesterol oxidase has now become one of the most widely used enzymes in clinical laboratories practice, biosynthesis and agricultural industries. Initial studies on the enzyme focused on its use for the determination of cholesterol in serum, HDL or LDL, which has direct implications in atherosclerosis, coronary heart disease, and other lipid disorders, and for determining the risk of heart attack and thrombosis. In addition, this enzyme shows potent insecticidal activity and thus has been used to track cell cholesterol and as a pest control in the agricultural industry, especially in transgenic crops. Besides, cholesterol oxidase from Streptomyces natalensis plays a critical role in the biosynthesis of the polyene macrolide pimaricin which is an important anti-fungal antibiotic used in the food industry. Moreover, cholesterol oxidase is also implicated in the manifestation of some of the diseases of bacterial (tuberculosis), viral (HIV) and non-viral prion origin (Alzheimer). Therefore, cholesterol oxidase is getting more and more attentions from pharmaceutical, medical, chemical and agricultural industries. However, the activity assays of cholesterol oxidase remain challenging, which is a stumbling block for the development and utilizing of this enzyme. Fortunately, Creative Enzymes made the accurate and convenient activity assay available for cholesterol oxidase by using spectrophotometric assays. Backed by the world’s most advanced instruments, we are committed to achieving the highest grade of customer satisfaction, and to improving service quality and process control constantly.

Figure: The crystal structure of B. sterolicum cholesterol oxidase complexed with a steroid substrate.
PDB: 1COY