Tetrahydrobiopterin

Tetrahydrobiopterin is the reduced form of dihydrobiopterin, an electron carrier in tyrosine biosynthesis (Figure 21.18). Tyrosine is only aromatic amino acid made in animals. The reaction is catalyzed by phenylalanine hydroxylase.

Phenylalanine + Dihydrobiopterin + O 2 <=> Tyrosine + Tetrahydrobiopterin + H 2O

Tetrahydrobiopterin is also part of the nitric oxide synthase enzyme.

See also: Phenylalanine Hydroxylase, Aromatic Amino Acid Utilization,

INTERNET LINKS:

> 1. Phenylalanine, Tyrosine, and Tryptophan Biosynthesis

> 2. Tyrosine Metabolism

> 3. The Nitric Oxide Home Page