title: Purification and characterization of the enzyme cholesterol oxidase from a new isolate of Streptomyces sp.
abstract: An extracellular cholesterol oxidase (cho) enzyme was isolated from the Streptomyces parvus, a new source and purified 18-fold by ion exchange and gel filtration chromatography. Specific activity of the purified enzyme was found to be 20 U/mg with a 55 kDa molecular mass. The enzyme was stable at pH 7.2 and 50 °C. The enzyme activity was inhibited in the presence of Pb(2+), Ag(2+), Hg(2+), and Zn(2+) and enhanced in the presence of Mn(2+). The enzyme activity was inhibited by the thiol-reducing reagents (DTT, β-mercaptoethanol), suggesting that disulfide linkage is essential for the enzyme activity. The enzyme activity was found to be maximum in the presence of Triton X-100 and X-114 detergents whereas sodium dodecyl sulfate fully inactivated the enzyme. The enzyme showed moderate stability towards all organic solvents except acetone, benzene, chloroform and the activity increased in the presence of isopropanol and ethanol. The K(m) value for the oxidation of cholesterol by this enzyme was 0.02 mM.
authors: Fermentation Technology Division, Central Drug Research Institute, Lucknow 226 001, Uttar Pradesh, India.
authors: Vandana
authors: V
authors: Praveen
authors: Akanksha
authors: A
authors: Srivastava
authors: C K M
authors: CK
authors: Tripathi
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D002789:Cholesterol Oxidase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D004795:Enzyme Stability; D007700:Kinetics; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012988:Soil Microbiology; D013302:Streptomyces / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002784:Cholesterol; D002789:Cholesterol Oxidase