Several criticisms of past attempts to produce experimental phenylketonuria are discussed, and a model that appears to meet these criticisms is presented. This model uses inhibition in rats of phenylalanine hydroxylase (EC 1.14.3.1) by p-chlorophenylalanine and supplementation with phenylalanine to produce a high ratio of phenylalanine to tyrosine in their blood. By this method, an experimental...

A full-length human phenylalanine hydroxylase cDNA has been recombined with a prokaryotic expression vector and introduced into Escherichia coli. Transformed bacteria express phenylalanine hydroxylase immunoreactive protein and pterin-dependent conversion of phenylalanine to tyrosine. Recombinant human phenylalanine hydroxylase produced in E. coli has been partially purified, and biochemical st...

The degree of inhibition of rat intestinal alkaline phosphatase by L-phenylalanine was highly pa-dependent and varied from 0 to 66% within a pH range of ‘7.8 to 10.4, exhibiting a peak at pH 9.2 and 8.7 for phenylphosphate and /3glycerophosphate, respectively. Vm,, was also a function of pH with and without the inhibitor. Rat intestinal alkaline phosphatase exhibited maximum enzyme activity at ...

The degree of inhibition of rat intestinal alkaline phosphatase by L-phenylalanine was highly pa-dependent and varied from 0 to 66% within a pH range of ‘7.8 to 10.4, exhibiting a peak at pH 9.2 and 8.7 for phenylphosphate and /3glycerophosphate, respectively. Vm,, was also a function of pH with and without the inhibitor. Rat intestinal alkaline phosphatase exhibited maximum enzyme activity at ...

A recent paper from this laboratory (1) reported the inhibition of the growth of Saccharomyces cerevisiae by &3-2-thienylalanine, an isostere of phenylalanine. This inhibitory action of thienylalanine was counteracted by phenylalanine. Thus, the thienylalanine was shown to act as an “antiphenylalanine” for this yeast. Tyrosine had no effect on the toxicity of the thienyl compound. Furthermore, ...

1. Studies on the inactivation of rat intestinal alkaline phosphatase by several metal-binding agents, namely EDTA, 8-hydroxyquinoline, pyridine-2,6-dicarboxylic acid, aoc'-bipyridyl, o-phenanthroline and sodium cyanide, indicated the functional role of a metal, probably zinc, in the catalysis. The metal ligands lowered stereospecific uncompetitive inhibition of the enzyme by L-phenylalanine by...

Phenylalanine inhibited thiazole biosynthesis in a thiamine-regulatory mutant of Escherichia coli, and the inhibition was overcome by tyrosine.

in a combination of amino acids. It was subsequently found that a mixture of phenylalanine and cysteine promoted partial reversal of the inhibition, but that in the presence of a B vitamin supplement, the activity of the cysteine was less pronounced, whereas a mixture of phenylalanine and glutamic acid showed even greater activity. The activity of the vitamin supplement resided in its niacin an...