IUBMB Enzyme Nomenclature


Accepted name: 4a-hydroxytetrahydrobiopterin dehydratase

Reaction: 4a-hydroxytetrahydrobiopterin = 6,7-dihydrobiopterin + H2O

For diagram of reactionclick here

Glossary: 4a-hydroxytetrahydrobiopterin = 6-[(1R,2S)-1,2-dihydroxypropyl]-5,6,7,8-tetrahydro-4a-hydroxypterin
6,7-dihydrobiopterin = 6-[(1R,2S)-1,2-dihydroxypropyl]-6,7-dihydropterin

Other name(s): 4α-hydroxy-tetrahydropterin dehydratase; 4a-carbinolamine dehydratase; pterin-4α-carbinolamine dehydratase; 4a-hydroxytetrahydrobiopterin hydro-lyase

Systematic name: a-hydroxytetrahydrobiopterin hydro-lyase (6,7-dihydrobiopterin-forming)

Comments: In concert with EC, 6,7-dihydropteridine reductase, the enzyme recycles 4a-hydroxytetrahydrobiopterin back to tetrahydrobiopterin, a cosubstrate for several enzymes, including aromatic amino acid hydroxylases. The enzyme is bifunctional, and also acts as a dimerization cofactor of hepatocyte nuclear factor-1α (HNF-1).

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 87683-70-3


1. Citron, B.A., Davis, M.D., Milstien, S., Gutierrez, J., Mendel, D.B., Crabtree, G.R. and Kaufman, S. Identity of 4a-carbinolamine dehydratase, a component of the phenylalanine hydroxylation system, and DCoH, a transregulator of homeodomain proteins. Proc. Natl. Acad. Sci. USA 89 (1992) 11891-11894. [PMID: 1465414]

2. Hauer, C.R., Rebrin, I., Thöny, B., Neuheiser, F., Curtius, H.C., Hunziker, P., Blau, N., Ghisla, S., Heizmann, C.W. Phenylalanine hydroxylase-stimulating protein: pterin-4α-carbinolamine dehydratase from rat and human liver. J. Biol. Chem. 268 (1993) 4828-4831. [PMID: 8444860]

3. Thony, B., Neuheiser, F., Blau, N. and Heizmann, C.W. Characterization of the human PCBD gene encoding the bifunctional protein pterin-4 α-carbinolamine dehydratase/dimerization cofactor for the transcription factor HNF-1 α. Biochem. Biophys. Res. Commun. 210 (1995) 966-973. [PMID: 7763270]

4. Endrizzi, J.A., Cronk, J.D., Wang, W., Crabtree, G.R. and Alber, T. Crystal structure of DCoH, a bifunctional, protein-binding transcriptional coactivator. Science 268 (1995) 556-559. [PMID: 7725101]

5. Cronk, J.D., Endrizzi, J.A. and Alber, T. High-resolution structures of the bifunctional enzyme and transcriptional coactivator DCoH and its complex with a product analogue. Protein Sci. 5 (1996) 1963-1972. [PMID: 8897596]

[EC created 1999, modified 2020]

Return to EC 4.2.1 home page
Return to EC 4.2 home page
Return to EC 4 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page