'''CRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE COMPLEXED WITH A STEROID SUBSTRATE. IMPLICATIONS FOR FAD DEPENDENT ALCOHOL OXIDASES'''
===CRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE COMPLEXED WITH A STEROID SUBSTRATE. IMPLICATIONS FOR FAD DEPENDENT ALCOHOL OXIDASES===
==Overview==
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Cholesterol oxidase from Brevibacterium sterolicum is a flavin-dependent enzyme that catalyzes the oxidation and isomerization of 3 beta-hydroxy steroids with a double bond at delta 5-delta 6 of the steroid ring backbone. The crystal structure of the free enzyme in the absence of a steroid substrate has previously been determined. In this paper we report the crystal structure of the complex of cholesterol oxidase with the steroid substrate dehydroisoandrosterone, refined at 1.8-A resolution. The final crystallographic R-value is 15.7% for all reflections between 10.0- and 1.8-A resolution. The steroid is buried within the protein in an internal cavity which, in the free enzyme crystal structure, was occupied by a lattice of water molecules. The conformations of a number of side chains lining the active-site cavity have changed in order to accommodate the steroid substrate. A loop region of the structure between residues 70 and 90 differs significantly between the substrate-free and substrate-bound forms of the enzyme, presumably to facilitate binding of the steroid. The hydroxyl group of the steroid substrate is hydrogen-bonded to both the flavin ring system of the FAD cofactor and a bound water molecule. FAD-dependent cholesterol oxidase shares significant structural homology with another flavoenzyme, glucose oxidase, suggesting that it might also be a member of the glucose-methanol-choline (GMC) oxidoreductase family. Although there is only limited sequence homology, a superposition of these two structures reveals a conserved histidine residue within hydrogen-bonding distance of the active-site water molecule.(ABSTRACT TRUNCATED AT 250 WORDS)
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==About this Structure==
==About this Structure==
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[[Category: Li, J.]]
[[Category: Li, J.]]
[[Category: Vrielink, A.]]
[[Category: Vrielink, A.]]
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Revision as of 06:02, 29 July 2008
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CRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE COMPLEXED WITH A STEROID SUBSTRATE. IMPLICATIONS FOR FAD DEPENDENT ALCOHOL OXIDASESCRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE COMPLEXED WITH A STEROID SUBSTRATE. IMPLICATIONS FOR FAD DEPENDENT ALCOHOL OXIDASES
3COX is a Single protein structure of sequence from Brevibacterium sterolicum. This structure supersedes the now removed PDB entry 1cox. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of cholesterol oxidase complexed with a steroid substrate: implications for flavin adenine dinucleotide dependent alcohol oxidases., Li J, Vrielink A, Brick P, Blow DM, Biochemistry. 1993 Nov 2;32(43):11507-15. PMID:8218217
