EC	1.14.13.97
Transferred entry:	taurochenodeoxycholate 6α-hydroxylase. Now EC 1.14.14.57, taurochenodeoxycholate 6α-hydroxylase
[EC 1.14.13.97 created 2005, deleted 2018]
EC	1.14.14.57
Accepted name:	taurochenodeoxycholate 6α-hydroxylase
Reaction:	(1) taurochenodeoxycholate + [reduced NADPH—hemoprotein reductase] + O2 = taurohyocholate + [oxidized NADPH—hemoprotein reductase] + H2O (2) lithocholate + [reduced NADPH—hemoprotein reductase] + O2 = hyodeoxycholate + [oxidized NADPH—hemoprotein reductase] + H2O
Glossary:	taurochenodeoxycholic acid = N-(3α,7α-dihydroxy-5β-cholan-24-oyl)taurine taurohyocholic acid = N-(3α,6α,7α-trihydroxy-5β-cholan-24-oyl)taurine hyodeoxycholate = 3α,6α-dihydroxy-5β-cholan-24-oate lithocholate = 3α-hydroxy-5β-cholan-24-oate
Other name(s):	CYP3A4; CYP4A21; taurochenodeoxycholate 6α-monooxygenase
Systematic name:	taurochenodeoxycholate,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (6α-hydroxylating)
Comments:	A cytochrome P-450 (heme-thiolate) protein. Requires cytochrome b5 for maximal activity. Acts on taurochenodeoxycholate, taurodeoxycholate and less readily on lithocholate and chenodeoxycholate. In adult pig (Sus scrofa), hyocholic acid replaces cholic acid as a primary bile acid [5].
References:	1.  Araya, Z. and Wikvall, K. 6α-Hydroxylation of taurochenodeoxycholic acid and lithocholic acid by CYP3A4 in human liver microsomes. Biochim. Biophys. Acta 1438 (1999) 47–54. [PMID: 10216279] 2.  Araya, Z., Hellman, U. and Hansson, R. Characterisation of taurochenodeoxycholic acid 6α-hydroxylase from pig liver microsomes. Eur. J. Biochem. 231 (1995) 855–861. [PMID: 7649186] 3.  Kramer, W., Sauber, K., Baringhaus, K.H., Kurz, M., Stengelin, S., Lange, G., Corsiero, D., Girbig, F., Konig, W. and Weyland, C. Identification of the bile acid-binding site of the ileal lipid-binding protein by photoaffinity labeling, matrix-assisted laser desorption ionization-mass spectrometry, and NMR structure. J. Biol. Chem. 276 (2001) 7291–7301. [PMID: 11069906] 4.  Lundell, K., Hansson, R. and Wikvall, K. Cloning and expression of a pig liver taurochenodeoxycholic acid 6α-hydroxylase (CYP4A21): a novel member of the CYP4A subfamily. J. Biol. Chem. 276 (2001) 9606–9612. [PMID: 11113117] 5.  Lundell, K. and Wikvall, K. Gene structure of pig sterol 12α-hydroxylase (CYP8B1) and expression in fetal liver: comparison with expression of taurochenodeoxycholic acid 6α-hydroxylase (CYP4A21). Biochim. Biophys. Acta 1634 (2003) 86–96. [PMID: 14643796] 6.  Russell, D.W. The enzymes, regulation, and genetics of bile acid synthesis. Annu. Rev. Biochem. 72 (2003) 137–174. [PMID: 12543708]
[EC 1.14.14.57 created 2005 asEC 1.14.13.97, transferred 2018 to EC 1.14.14.57]