3COX

CRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE COMPLEXED WITH A STEROID SUBSTRATE. IMPLICATIONS FOR FAD DEPENDENT ALCOHOL OXIDASES

Replaces:  1COX

Summary for 3COX

• Entry DOI: 10.2210/pdb3cox/pdb
• Descriptor: CHOLESTEROL OXIDASE, FLAVIN-ADENINE DINUCLEOTIDE (3 entities in total)
• Functional Keywords: oxidoreductase(oxygen receptor)
• Biological source: Brevibacterium sterolicum
• Cellular location: Secreted: P22637
• Total number of polymer chains: 1
• Total formula weight: 55677.29

Authors

Vrielink, A.,Li, J.,Brick, P.,Blow, D.M. (deposition date: 1993-06-14, release date: 1993-10-31, Last modification date: 2024-02-21)

Primary citation

Li, J.,Vrielink, A.,Brick, P.,Blow, D.M.
Crystal structure of cholesterol oxidase complexed with a steroid substrate: implications for flavin adenine dinucleotide dependent alcohol oxidases.
Biochemistry, 32:11507-11515, 1993

PubMed Abstract: 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)

PubMed: 8218217
DOI: 10.1021/bi00094a006

Experimental method

X-RAY DIFFRACTION (1.8 Å)