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Template:Chembox new Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Synonyms and Keywords: 5,6,7,8-tetrahydrobiopterin, BH4


Tetrahydrobiopterin is a cofactor in the synthesis of nitric oxide. It is also essential in the conversion of phenylalanine to tyrosine by the enzyme phenylalanine-4-hydroxylase; the conversion of tyrosine to L-dopa by the enzyme tyrosine hydroxylase; and conversion of tryptophan to 5-hydroxytryptophan via tryptophan hydroxylase.

Clinical significance

A defect in BH4 production and/or a defect in the enzyme dihydropteridine reductase (DHPR) causes phenylketonuria type IV, as well as dopa-responsive dystonias.


Tetrahydrobiopterin is synthesized from GTP via two intermediates.


Thony B, Auerbach G, Blau N (2000). "Tetrahydrobiopterin biosynthesis, regeneration and functions". Biochem J. 347 Pt 1: 1–16. PMID 10727395.

See also

External links

Template:Enzyme cofactors Template:WikiDoc Sources