Partial purification and characterization of rat liver phenylalanine hydroxylase phosphatase.
A phosphatase which catalyzes the release of 32Pi from 32P-labeled phenylalanine hydroxylase has been purified about 50-fold from rat liver extracts. The phosphatase is able to catalyze the removal of only 70 to 80% of the 32Pi leaving about the same amount of Pi still bound to the hydroxylase as was originally present in the native enzyme. Dephosphorylation is accompanied by a corresponding loss in phenylalanine hydroxylase activity when the activity is measured with the natural cofactor, tetrahydrobiopterin, but not when measured with the synthetic cofactor, 6-methyltetrahydropterin. The partially purified phosphatase has very low activity toward p-nitrophenylphosphate, histone phosphate, and phosphorylase a. The activity toward these substrates has not been purified to the same extent as the phenylalanine hydroxylase phosphatase activity.
D000818:Animals; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D010651:Phenylalanine Hydroxylase; D010749:Phosphoprotein Phosphatases / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity
D010651:Phenylalanine Hydroxylase; D010749:Phosphoprotein Phosphatases