EC - Taurochenodeoxycholate 6α-hydroxylase

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IntEnz Enzyme Nomenclature


Accepted name:
taurochenodeoxycholate 6α-hydroxylase
Other names:
taurochenodeoxycholate 6α-monooxygenase
Systematic name:
taurochenodeoxycholate,NADPH:oxygen oxidoreductase (6α-hydroxylating)




A heme-thiolate protein (P-450). 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].

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00081
Structural data: CSA , EC2PDB
Gene Ontology: GO:0033780


  1. Araya, Z. and Wikvall, K.
    6α-hydroxylation of taurochenodeoxycholic acid and lithocholic acid by CYP3A4 in human liver microsomes.
    Biochim. Biophys. Acta 1438: 47-54 (1999). [PMID: 10216279]
  2. Araya, Z., Hellman, U. and Hansson, R.
    Characterisation of taurochenodeoxycholic acid 6α-hydroxylase from pig liver microsomes.
    Eur. J. Biochem. 231: 855-861 (1995). [PMID: 7649186]
  3. Kramer, W., Sauber, K., Baringhaus, K.-H., Kurz, M., Stengelin, S., Lange, G., Corsiero, D., Girbig, F., König, 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: 7291-7301 (2001). [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: 9606-9612 (2001). [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: 86-96 (2003). [PMID: 14643796]
  6. Russell, D.W.
    The enzymes, regulation, and genetics of bile acid synthesis.
    Annu. Rev. Biochem. 72: 137-174 (2003). [PMID: 12543708]

[EC created 2005]