tailieunhanh - Báo cáo khoa học: Cholesterol oxidase: physiological functions

An important aspect of catalysis performed by cholesterol oxidase (3b-hy-droxysteroid oxidase) concerns the nature of its association with the lipid bilayer that contains the sterol substrate. Efficient catalytic turnover is affected by the association of the protein with the membrane as well as the solubility of the substrate in the lipid bilayer. | MINIREVIEW Cholesterol oxidase physiological functions Joseph Kreit1 and Nicole S. Sampson2 1 Laboratory of Biochemistry and Immunology Department of Biology Faculty of Sciences Mohammed V University Rabat Morocco 2 Department of Chemistry Stony Brook University NY USA Keywords bilayer catabolism cholesterol oxidase GMC oxidoreductase interfacial enzyme lipid phase macrolide biosynthesis membrane sterol virulence Correspondence N. S. Sampson Department of Chemistry Stony Brook University New York 11794-3400 USA Fax 1 631-632-5731 Tel 1 631-632-7952 E-mail Received 26 July 2009 revised 2 September 2009 accepted 10 September 2009 doi An important aspect of catalysis performed by cholesterol oxidase 3b-hy-droxysteroid oxidase concerns the nature of its association with the lipid bilayer that contains the sterol substrate. Efficient catalytic turnover is affected by the association of the protein with the membrane as well as the solubility of the substrate in the lipid bilayer. In this review the binding of cholesterol oxidase to the lipid bilayer its turnover of substrates presented in different physical environments and how these conditions affect substrate specificity are discussed. The physiological functions of the enzyme in bacterial metabolism pathogenesis and macrolide biosynthesis are reviewed in this context. Introduction 3b-Hydroxysteroid oxygen oxidoreductase EC commonly known as cholesterol oxidase ChOx is a flavoenzyme that catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one and has been well characterized structurally and chemically see the first review of this miniseries . The enzyme is extracellular and occurs in a secreted form and or a cellsurface-associated form depending on the producer microorganism and growth conditions. Both forms are products of the same gene. The secreted form is a soluble globular protein and the X-ray crystal structures 1-3 .