The first and rate limiting step in serotonin (5-HT) biosynthesis is catalyzed by tryptophan hydroxylase. The enzyme requires iron(II), tetrahydrobiopterin, and dioxygen cofactors for the hydroxylation of L-tryptophan to 5-hydroxytryptophan. Tryptophan hydroxylase belongs to a small family of monooxygenases that utilize tetrahydrobiopterins. Other members are phenylalanine hydroxylase and tyrosine hydroxylase (Fitzpatrick, PF, 1999; Walther et al, 2003).
Walther, DJ, Peter, JU, Bashammakh, S, Hörtnagl, H, Voits, M, Fink, H, Bader, M
Wang, L, Erlandsen, H, Haavik, J, Knappskog, PM, Stevens, RC
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