6-PyruvoylTetrahydropterin Synthase is part of the family of lyases， specifically those carbon-oxygen lyases acting on phosphates. 6-PyruvoylTetrahydropterin Synthase catalyzes the elimination of inorganic triphosphate from dihydroneopterin triphosphate， which is the second and irreversible step in the biosynthesis of tetrahydrobiopterin from GTP. Tetrahydrobiopterin， is a necessary cofactor and regulator of a range of enzyme activities， including enzymes involved in serotonin biosynthesis and NO synthase activity. Mutations in 6-PyruvoylTetrahydropterin Synthase gene result in hyperphenylalaninemia.
