KEGG   ENZYME: 1.14.13.96Help
Entry
EC 1.14.13.96               Enzyme                                 

Name
5beta-cholestane-3alpha,7alpha-diol 12alpha-hydroxylase;
5beta-cholestane-3alpha,7alpha-diol 12alpha-monooxygenase;
sterol 12alpha-hydroxylase (ambiguous);
CYP8B1;
cytochrome P450 8B1
Class
Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor
BRITE hierarchy
Sysname
5beta-cholestane-3alpha,7alpha-diol,NADPH:oxygen oxidoreductase (12alpha-hydroxylating)
Reaction(IUBMB)
5beta-cholestane-3alpha,7alpha-diol + NADPH + H+ + O2 = 5beta-cholestane-3alpha,7alpha,12alpha-triol + NADP+ + H2O [RN:R07204]
Reaction(KEGG)
Substrate
5beta-cholestane-3alpha,7alpha-diol [CPD:C05452];
NADPH [CPD:C00005];
H+ [CPD:C00080];
O2 [CPD:C00007]
Product
5beta-cholestane-3alpha,7alpha,12alpha-triol [CPD:C05454];
NADP+ [CPD:C00006];
H2O [CPD:C00001]
Comment
A heme-thiolate protein (P-450). This is the key enzyme in the biosynthesis of the bile acid cholic acid (3alpha,7alpha,12alpha-trihydroxy-5beta-cholanoic acid). The activity of this enzyme determines the biosynthetic ratio between cholic acid and chenodeoxycholic acid [3]. The enzyme can also hydroxylate the substrate at the 25 and 26 position, but to a lesser extent [1].
History
EC 1.14.13.96 created 2005
Orthology
K07431  
sterol 12-alpha-hydroxylase
Genes
HSA: 
1582(CYP8B1)
PTR: 
PPS: 
GGO: 
PON: 
NLE: 
MCC: 
MCF: 
RRO: 
CJC: 
100402181(CYP8B1)
MMU: 
13124(Cyp8b1)
RNO: 
81924(Cyp8b1)
CGE: 
NGI: 
OCU: 
100009301(CYP8B1)
TUP: 
CFA: 
AML: 
UMR: 
FCA: 
PTG: 
BTA: 
538964(CYP8B1)
BOM: 
PHD: 
CHX: 
OAS: 
SSC: 
403328(CYP8B1)
CFR: 
BACU: 
LVE: 
ECB: 
MYB: 
MYD: 
PALE: 
MDO: 
100026549(CYP8B)
SHR: 
OAA: 
GGA: 
425055(CYP8B1)
MGP: 
CJO: 
APLA: 
TGU: 
GFR: 
FAB: 
PHI: 
CCW: 
FPG: 
FCH: 
CLV: 
ASN: 
AMJ: 
102573091(CYP8B1)
PSS: 
CMY: 
ACS: 
PBI: 
GJA: 
XLA: 
379482(cyp8b1)
XTR: 
100488168(cyp8b1)
DRE: 
445281(cyp8b1)
TRU: 
MZE: 
OLA: 
XMA: 
LCM: 
CMK: 
UMA: 
 » show all
Taxonomy
Reference
1  [PMID:6811268]
  Authors
Hansson R, Wikvall K.
  Title
Hydroxylations in biosynthesis of bile acids. Cytochrome P-450 LM4 and 12alpha-hydroxylation of 5beta-cholestane-3alpha, 7alpha-diol.
  Journal
Eur. J. Biochem. 125 (1982) 423-9.
Reference
2  [PMID:6766451]
  Authors
Hansson R, Wikvall K.
  Title
Hydroxylations in biosynthesis and metabolism of bile acids. Catalytic properties of different forms of cytochrome P-450.
  Journal
J. Biol. Chem. 255 (1980) 1643-9.
Reference
3  [PMID:14643796]
  Authors
Lundell K, Wikvall K.
  Title
Gene structure of pig sterol 12alpha-hydroxylase (CYP8B1) and expression in fetal liver: comparison with expression of taurochenodeoxycholic acid 6alpha-hydroxylase (CYP4A21).
  Journal
Biochim. Biophys. Acta. 1634 (2003) 86-96.
  Sequence
[ssc:403328]
Reference
4  [PMID:10747975]
  Authors
del Castillo-Olivares A, Gil G.
  Title
Alpha 1-fetoprotein transcription factor is required for the expression of sterol 12alpha -hydroxylase, the specific enzyme for cholic acid synthesis. Potential role in the bile acid-mediated regulation of gene transcription.
  Journal
J. Biol. Chem. 275 (2000) 17793-9.
Reference
5  [PMID:12069850]
  Authors
Yang Y, Zhang M, Eggertsen G, Chiang JY.
  Title
On the mechanism of bile acid inhibition of rat sterol 12alpha-hydroxylase gene (CYP8B1) transcription: roles of alpha-fetoprotein transcription factor and hepatocyte nuclear factor 4alpha.
  Journal
Biochim. Biophys. Acta. 1583 (2002) 63-73.
Reference
6  [PMID:12543708]
  Authors
Russell DW.
  Title
The enzymes, regulation, and genetics of bile acid synthesis.
  Journal
Annu. Rev. Biochem. 72 (2003) 137-74.
  Sequence
[hsa:1582] [mmu:13124]
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 

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