Biosynthesis and regeneration of tetrahydrobiopterin Guanosine triphosphate(GTP) GTPch 35 Neopterin+-Dihydroneopterin triphosphate PTPS 6-Pyruvoyl-tetrahydropterin v SR Phe Tyrosine Tryptophan tetrahydropterin( BH4) DHPR PAH TH TPH PCD q-dihydrobiopterin(BH2) pterin Try L-DOPA 5-OH- Tryptophan 4a-carbinolamineBiosynthesis and regeneration of tetrahydrobiopterin Guanosine triphosphate（GTP） GTPch p35 Neopterin Dihydroneopterin triphosphate (N) PTPS - + 6-Pyruvoyl-tetrahydropterin SR Phe Tyrosine Tryptophan tetrahydropterin(BH4 ) DHPR PAH TH TPH PCD q-dihydrobiopterin(BH2 ) pterin- Try L-DOPA 5-OH￾Tryptophan 4a-carbinolamine biopterin Dopamine