title: The activity of 2,4,5-triamino-6-hydroxypyrimidine in the phenylalanine hydroxylase system.
abstract: The pyrimidine moiety of a pterin, 2,4,5-triamino-6-hydroxypyrimidine, has been found to be active in the phenylalanine-hydroxylating system. The phenylalanine-dependent, phenylalanine hydroxylase-catalyzed reaction in the presence of the pyrimidine is largely, but not completely, uncoupled; the ratio of DPNH oxidized to tyrosine formed is about 20 to 1. In addition to the pyrimidine having activity with phenylalanine hydroxylase, a product of the pyrimidine is also a substrate for dihydropteridine reductase. The activity of the pyrimidine with the hydroxylase indicates that neither carbon atoms 6 or 7 of the pterin ring is involved in activation of oxygen during the hydroxylase-catalyzed reaction.
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D009243:NAD; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism; D010651:Phenylalanine Hydroxylase / Q000378:metabolism*; D011743:Pyrimidines; D051381:Rats
chemical_list: D011743:Pyrimidines; D009243:NAD; D010544:Peroxidases; D002374:Catalase; D010651:Phenylalanine Hydroxylase; C001429:6-hydroxy-2,4,5-triaminopyrimidine