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C8649 Sigma-Aldrich

Cholesterol Oxidase from Streptomyces sp.

lyophilized powder, ≥20 units/mg protein

Synonym: Cholesterol: oxygen oxidoreductase



Related Categories 1.1.x.x Acting on hydroxyl groups, 1.x.x.x Oxidoreductases, Application Index, Biochemicals and Reagents, Cell Biology,
Quality Level   200
form   lyophilized powder
mol wt   ~34 kDa
composition   protein, 55-65% biuret
solubility   50 mM potassium phosphate buffer, pH 7.0: soluble (Cold)
shipped in   dry ice
storage temp.   −20°C


General description

Cholesterol Oxidase produced from Streptomyces sp corresponds to a molecular weight of 62 kDa. It has a pH and temperature optimum of 7 and 37 °C, respectively. Cholesterol Oxidase comprises a FAD-binding and a steroid-binding domain.


Cholesterol oxidase from Streptomyces has been used in a study to assess the relationship between the micellar structure of model bile and the activity of esterase. Cholesterol oxidase from Streptomyces has also been used in a study to investigate the effects of sphingomyelin degradation on cell cholesterol oxidizability and steady-state distribution between the cell surface and the cell interior.

Cholesterol oxidase is used to determine serum cholesterol. The enzyme also finds application in the microanalysis of steroids in food samples and in distinguishing 3-ketosteroids from 3β-hydroxysteroids. Transgenic plants expressing cholesterol oxidase are being investigated in the fight against the cotton boll weevil. CHOD has also been used as a molecular probe to elucidate cellular membrane structures.


100, 250 units in glass bottle

Biochem/physiol Actions

Cholesterol Oxidase from microorganisms use cholesterol for carbon and energy. It is useful in diagnostic assays involving cholesterol, especially in lipid disorders. Cholesterol oxidase has an insecticidal property and aids protection against boll weevil larvae. The Streptomyces sp cholesterol oxidase has long shelf-life with good performance.

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, which is then isomerized to cholest-4-en-3-one with the release of H2O2.

Physical properties

Isoelectric point : 5.1 ± 0.1 and 5.4 ± 0.1
Michaelis constant : 4.3 x 10‾5M(Cholesterol)
Inhibitors : Ionic detergents, Hg++, Ag+
Optimum pH : 6.5 − 7.0
Optimum temperature : 45 – 50°C
pH Stability : pH 5.0 – 10.0 (25°C, 20hr)
Thermal stability : Below 45°C (pH 7.0, 15min)

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.

Physical form

lyophilized powder containing bovine serum albumin and sugars as stabilizers

Preparation Note

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

Safety & Documentation

Safety Information

Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable


Certificate of Analysis (COA)

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Certificate of Origin (COO)

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Protocols & Articles


Assay Procedure for Cholesterol Oxidase

The appearance of quinoneimine dye formed when coupled with 4-aminoantipyrine and phenol is measured at 500nm by spectrophotometry.
Keywords: Atomic absorption spectroscopy, Extinction coefficient

Enzymatic Assay of Cholesterol Oxidase

To standardize a procedure for the determination of the enzymatic assay of Cholesterol Oxidase.
Keywords: Enzyme activity, Extinction coefficient, Isomerizations

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