25-hydroxycholesterol 7α-hydroxylase

25-hydroxycholesterol 7alpha-hydroxylase (EC 1.14.13.100, 25-hydroxycholesterol 7alpha-monooxygenase, CYP7B1, CYP7B1 oxysterol 7alpha-hydroxylase) is an enzyme with systematic name cholest-5-ene-3beta,25-diol,NADPH:oxygen oxidoreductase (7alpha-hydroxylating).^[1]^[2]^[3]^[4] This enzyme catalyses the following chemical reaction

(1) cholest-5-ene-3beta,25-diol + NADPH + H⁺ + O₂

\rightleftharpoons

cholest-5-ene-3beta,7alpha,25-triol + NADP⁺ + H₂O

(2) cholest-5-ene-3beta,27-diol + NADPH + H⁺ + O₂

\rightleftharpoons

cholest-5-ene-3beta,7alpha,27-triol + NADP⁺ + H₂O

25-hydroxycholesterol 7α-hydroxylase is a heme-thiolate protein (P-450).

References

↑ Toll, A., Wikvall, K., Sudjana-Sugiaman, E., Kondo, K.H. and Björkhem, I. (1994). "7α hydroxylation of 25-hydroxycholesterol in liver microsomes. Evidence that the enzyme involved is different from cholesterol 7α-hydroxylase". Eur. J. Biochem. 224: 309–316. doi:10.1111/j.1432-1033.1994.00309.x. PMID 7925343.
↑ Li-Hawkins, J., Lund, E.G., Bronson, A.D. and Russell, D.W. (2000). "Expression cloning of an oxysterol 7α-hydroxylase selective for 24-hydroxycholesterol". J. Biol. Chem. 275: 16543–16549. doi:10.1074/jbc.M001810200. PMID 10748047.
↑ Ren, S., Marques, D., Redford, K., Hylemon, P.B., Gil, G., Vlahcevic, Z.R. and Pandak, W.M. (2003). "Regulation of oxysterol 7alpha-hydroxylase (CYP7B1) in the rat". Metabolism 52: 636–642. doi:10.1053/meta.2003.50106. PMID 12759897.
↑ Russell, D.W. (2003). "The enzymes, regulation, and genetics of bile acid synthesis". Annu. Rev. Biochem. 72: 137–174. doi:10.1146/annurev.biochem.72.121801.161712. PMID 12543708.

External links

25-hydroxycholesterol 7alpha-hydroxylase at the US National Library of Medicine Medical Subject Headings (MeSH)

Oxidoreductases: dioxygenases, including steroid hydroxylases (EC 1.14)

1.14.11: 2-oxoglutarate	Prolyl hydroxylase Lysyl hydroxylase

1.14.13: NADH or NADPH	Flavin-containing monooxygenase FMO1 FMO2 FMO3 FMO4 FMO5 Nitric oxide synthase NOS1 NOS2 NOS3 Cholesterol 7 alpha-hydroxylase Methane monooxygenase 3A4 Lanosterol 14 alpha-demethylase 24-hydroxycholesterol 7α-hydroxylase

1.14.14: reduced flavin or flavoprotein	19A1 2D6 2E1

1.14.15: reduced iron-sulfur protein	11B1 11B2 11A1

1.14.16: reduced pteridine (BH4 dependent)	Phenylalanine hydroxylase Tyrosine hydroxylase Tryptophan hydroxylase

1.14.17: reduced ascorbate	Dopamine beta-hydroxylase

1.14.18-19: other	Tyrosinase Stearoyl-CoA desaturase-1

1.14.99 - miscellaneous	Cyclooxygenase Heme oxygenase (HMOX1) Squalene monooxygenase 17A1 21A2

Enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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