The Enzyme Database

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EC 1.14.13.126      
Transferred entry: vitamin D3 24-hydroxylase. Now EC 1.14.15.16, vitamin D3 24-hydroxylase
[EC 1.14.13.126 created 2011, deleted 2016]
 
 
EC 1.14.15.16     
Accepted name: vitamin D3 24-hydroxylase
Reaction: (1) calcitriol + 2 reduced adrenodoxin + 2 H+ + O2 = calcitetrol + 2 oxidized adrenodoxin + H2O
(2) calcidiol + 2 reduced adrenodoxin + 2 H+ + O2 = secalciferol + 2 oxidized adrenodoxin + H2O
For diagram of calciferol biosynthesis, click here
Glossary: calcidiol = 25-hydroxyvitamin D3 = (3S,5Z,7E)-9,10-seco-5,7,10(19)-cholestatriene-3,25-diol
calcitriol = 1α,25-dihydroxyvitamin D3 = (1S,3R,5Z,7E)-9,10-seco-5,7,10(19)-cholestatriene-1,3,25-triol
calcitetrol = 1α,24R,25-trihydroxyvitamin D3 = (1S,3R,5Z,7E,24R)-9,10-seco-5,7,10(19)-cholestatriene-1,3,24,25-tetrol
secalciferol = (24R)-24,25-dihydroxycalciol = 24R,25-dihydroxyvitamin D3 = (3R,5Z,7E,24R)-9,10-seco-5,7,10(19)-cholestatriene-3,24,25-triol
Other name(s): CYP24A1
Systematic name: calcitriol,adrenodoxin:oxygen oxidoreductase (24-hydroxylating)
Comments: This mitochondrial cytochrome P-450 enzyme requires adrenodoxin. The enzyme can perform up to 6 rounds of hydroxylation of the substrate calcitriol leading to calcitroic acid. The human enzyme also shows 23-hydroxylating activity leading to 1,25 dihydroxyvitamin D3-26,23-lactone as end product while the mouse and rat enzymes do not. The initial source of the electrons is NADPH, which transfers the electrons to the adrenodoxin via EC 1.18.1.6, adrenodoxin-NADP+ reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Masuda, S., Strugnell, S.A., Knutson, J.C., St-Arnaud, R. and Jones, G. Evidence for the activation of 1α-hydroxyvitamin D2 by 25-hydroxyvitamin D-24-hydroxylase: delineation of pathways involving 1α,24-dihydroxyvitamin D2 and 1α,25-dihydroxyvitamin D2. Biochim. Biophys. Acta 1761 (2006) 221–234. [DOI] [PMID: 16516540]
2.  Hamamoto, H., Kusudo, T., Urushino, N., Masuno, H., Yamamoto, K., Yamada, S., Kamakura, M., Ohta, M., Inouye, K. and Sakaki, T. Structure-function analysis of vitamin D 24-hydroxylase (CYP24A1) by site-directed mutagenesis: amino acid residues responsible for species-based difference of CYP24A1 between humans and rats. Mol. Pharmacol. 70 (2006) 120–128. [DOI] [PMID: 16617161]
3.  Sakaki, T., Kagawa, N., Yamamoto, K. and Inouye, K. Metabolism of vitamin D3 by cytochromes P450. Front. Biosci. 10 (2005) 119–134. [PMID: 15574355]
4.  Prosser, D.E., Kaufmann, M., O'Leary, B., Byford, V. and Jones, G. Single A326G mutation converts human CYP24A1 from 25-OH-D3-24-hydroxylase into -23-hydroxylase, generating 1α,25-(OH)2D3-26,23-lactone. Proc. Natl. Acad. Sci. USA 104 (2007) 12673–12678. [DOI] [PMID: 17646648]
5.  Kusudo, T., Sakaki, T., Abe, D., Fujishima, T., Kittaka, A., Takayama, H., Hatakeyama, S., Ohta, M. and Inouye, K. Metabolism of A-ring diastereomers of 1α,25-dihydroxyvitamin D3 by CYP24A1. Biochem. Biophys. Res. Commun. 321 (2004) 774–782. [DOI] [PMID: 15358094]
6.  Sawada, N., Kusudo, T., Sakaki, T., Hatakeyama, S., Hanada, M., Abe, D., Kamao, M., Okano, T., Ohta, M. and Inouye, K. Novel metabolism of 1α,25-dihydroxyvitamin D3 with C24-C25 bond cleavage catalyzed by human CYP24A1. Biochemistry 43 (2004) 4530–4537. [DOI] [PMID: 15078099]
7.  Prosser, D.E. and Jones, G. Enzymes involved in the activation and inactivation of vitamin D. Trends Biochem. Sci. 29 (2004) 664–673. [DOI] [PMID: 15544953]
[EC 1.14.15.16 created 2011 as EC 1.14.13.126, transferred 2016 to EC 1.14.15.16]
 
 
EC 1.14.15.18     
Accepted name: calcidiol 1-monooxygenase
Reaction: (1) calcidiol + 2 reduced adrenodoxin + 2 H+ + O2 = calcitriol + 2 oxidized adrenodoxin + H2O
(2) secalciferol + 2 reduced adrenodoxin + 2 H+ + O2 = calcitetrol + 2 oxidized adrenodoxin + H2O
For diagram of calciferol biosynthesis, click here
Glossary: calcidiol = 25-hydroxyvitamin D3 = (3S,5Z,7E)-9,10-seco-5,7,10(19)-cholestatriene-3,25-diol
calcitriol = 1α,25-dihydroxyvitamin D3 = (1S,3R,5Z,7E)-9,10-seco-5,7,10(19)-cholestatriene-1,3,25-triol
secalciferol = (24R),25-dihydroxyvitamin D3 = (3S,5Z,7E,24R)-9,10-secocholesta-5,7,10-triene-3,24,25-triol
calcitetrol = 1α,(24R),25-dihydroxyvitamin D3 = (1S,3R,5Z,7E,24R,25)-9,10-secocholesta-5,7,10(19)-triene-1,3,24,25-tetrol
Other name(s): 25-hydroxycholecalciferol 1-hydroxylase; 25-hydroxycholecalciferol 1-monooxygenase; 1-hydroxylase-25-hydroxyvitamin D3; 25-hydroxy D3-1α-hydroxylase; 25-hydroxycholecalciferol 1α-hydroxylase; 25-hydroxyvitamin D3 1α-hydroxylase
Systematic name: calcidiol,adrenodoxin:oxygen oxidoreductase (1-hydroxylating)
Comments: A P-450 (heme-thiolate) enzyme found in mammals.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9081-36-1
References:
1.  Gray, R.W., Omdahl, J.L., Ghazarian, J.G. and De Luca, H.F. 25-Hydroxycholecalciferol-1-hydroxylase. Subcellular location and properties. J. Biol. Chem. 247 (1972) 7528–7532. [PMID: 4404596]
2.  Sakaki, T., Sawada, N., Takeyama, K., Kato, S. and Inouye, K. Enzymatic properties of mouse 25-hydroxyvitamin D3 1 α-hydroxylase expressed in Escherichia coli. Eur. J. Biochem. 259 (1999) 731–738. [DOI] [PMID: 10092858]
3.  Sawada, N., Sakaki, T., Kitanaka, S., Takeyama, K., Kato, S. and Inouye, K. Enzymatic properties of human 25-hydroxyvitamin D3 1α-hydroxylase coexpression with adrenodoxin and NADPH-adrenodoxin reductase in Escherichia coli. Eur. J. Biochem. 265 (1999) 950–956. [DOI] [PMID: 10518789]
[EC 1.14.15.18 created 1976 as EC 1.14.13.13, transferred 2016 to EC 1.14.15.18]
 
 


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