Cholesterol oxidase

{{Short description|Class of enzymes}} {{infobox enzyme | Name = cholesterol oxidase | EC_number = 1.1.3.6 | CAS_number = 9028-76-6 | GO_code = 0016995 | image = | width = | caption = }} {{Infobox protein family | Symbol = Chol_subst-bind | Name = Cholesterol oxidase substrate-binding domain | image = PDB 1i19 EBI.jpg | width = | caption = crystal structure of cholesterol oxidase from b.sterolicum | Pfam = PF09129 | Pfam_clan = CL0277 | InterPro = IPR015213 | SMART = | PROSITE = | MEROPS = | SCOP = 1i19 | TCDB = | OPM family = | OPM protein = | CAZy = | CDD = }} In enzymology, '''cholesterol oxidase''' ({{EC number|1.1.3.6}}) is an enzyme that catalyzes the chemical reaction

{{chemrxn|width=55%| {{chemrxn/cpd|cholesterol }} {{chemrxn/arw|direction=reversible|fwd_in={{chem2|O2}}|fwd_out={{chem2|H2O2}}|rev_in={{chem2|H2O2}}|rev_out={{chem2|O2}} }} {{chemrxn/cpd|qid=Q27098418|caption=cholesterone }} }}

The two substrates of this enzyme are cholesterol and oxygen. Its products are cholest-4-en-3-one (cholesterone) and hydrogen peroxide.<ref>{{KEGG enzyme|1.1.3.6}}</ref><ref>{{cite journal | author = Richmond W | year = 1973 | title = Preparation and properties of a cholesterol oxidase from Nocardia sp. and its application to the enzymatic assay of total cholesterol in serum | journal = Clin. Chem. | volume = 19 | pages = 1350–6 | pmid = 4757363 | issue = 12 | doi = 10.1093/clinchem/19.12.1350 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Stadtman TC, Cherkes A, Anfinsen CB | year = 1954 | title = Studies on the microbiological degradation of cholesterol | journal = J. Biol. Chem. | volume = 206 | pages = 511–23 | pmid = 13143010 | issue = 2 | doi = 10.1016/S0021-9258(19)50819-5 | doi-access = free }}</ref>

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with oxygen as acceptor. The systematic name of this enzyme class is '''cholesterol:oxygen oxidoreductase'''. Other names in common use include '''cholesterol- O2 oxidoreductase''', '''3beta-hydroxy steroid oxidoreductase''', and '''3beta-hydroxysteroid:oxygen oxidoreductase'''. This enzyme participates in bile acid biosynthesis.

The substrate-binding domain found in some bacterial cholesterol oxidases is composed of an eight-stranded mixed beta-pleated sheet and six alpha-helices. This domain is positioned over the isoalloxazine ring system of the FAD cofactor bound by the FAD-binding domain and forms the roof of the active site cavity, allowing for catalysis of oxidation and isomerisation of cholesterol to cholest-4-en-3-one.<ref name="pmid11397813">{{cite journal | vauthors = Coulombe R, Yue KQ, Ghisla S, Vrielink A | author-link4=Alice Vrielink|title = Oxygen access to the active site of cholesterol oxidase through a narrow channel is gated by an Arg-Glu pair | journal = J. Biol. Chem. | volume = 276 | issue = 32 | pages = 30435–41 |date=August 2001 | pmid = 11397813 | doi = 10.1074/jbc.M104103200 | doi-access = free }}</ref>

==Structural studies==

As of late 2007, 14 structures have been solved for this class of enzymes, with PDB accession codes {{PDB link|1B4V}}, {{PDB link|1B8S}}, {{PDB link|1CBO}}, {{PDB link|1CC2}}, {{PDB link|1COY}}, {{PDB link|1I19}}, {{PDB link|1IJH}}, {{PDB link|1MXT}}, {{PDB link|1N1P}}, {{PDB link|1N4U}}, {{PDB link|1N4V}}, {{PDB link|1N4W}}, {{PDB link|2GEW}}, and {{PDB link|3COX}}.

==References== {{reflist}}

Category:Protein domains Category:EC 1.1.3 Category:Enzymes of known structure