Phenylalanine analogues as inhibitors of phenylalanine-hydroxylase from rat liver. New conclusions concerning kinetic behaviors of the enzyme.
The conversion of phenylalanine to tyrosine is catalysed by phenylalanine-hydroxylase. The substrate phenylalanine shows two effects: (1) allosteric transition at low phenylalanine concentrations, (2) excess substration inhibition. The molecular structure of phenylalanine-hydroxylase has not yet been elucidated. However, a tetrameric structure has been proposed. The Kinetic analysis with respect to substrate analogues suggest the existence of three types of sites on each protomer: (1) a catalytic site, (2) a non-competitive inhibitory site, (3) a positive cooperative site. Use of the enzyme's natural cofactor, tetrahydrobiopterin, has been emphasized to ensure good interpretation of the kinetic results of the phenylalanine-hydroxylase effectors.
D000495:Allosteric Site; D000818:Animals; D001665:Binding Sites; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010651:Phenylalanine Hydroxylase / Q000037:antagonists & inhibitors*; D051381:Rats
D010649:Phenylalanine; D010651:Phenylalanine Hydroxylase