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, ...

The cathepsin B inhibitor, benzyloxycarbonyl-phenylalanine-alanine-fluoromethyl ketone (z-FA-FMK) readily inhibits anti-CD3-induced human T cell proliferation, whereas the analogue benzyloxycarbonyl-phenylalanine-alanine-diazomethyl ketone (z-FA-DMK) had no effect. In contrast, benzyloxycarbonyl-phenylalanine-alanine-chloromethyl ketone (z-FA-CMK) was toxic. The inhibition of T cell proliferati...

Belton, N. R., Crombie, J. D., Robins, S. P., Stephen, R., and Farquhar, J. W. (1973). Archives of Disease in Childhood, 48, 472. Measurement of phenylalanine in routine care of phenylketonuric children. Fluorimetry, paper and column chromatography, and bacterial inhibition assay have been compared in the quantitation of serum or blood phenylalanine at levels ranging from 1 to over 30 mg/100 ml...

Maximum inhibition of phenylalanine hydroxylase activity in the liver (85%) and in the kidney (50%) of suckling rats required the administration of over 9 mumol of p-chlorophenylalanine/10g body weight. Despite the decrease in the total activity from 184 to 34 units per 10g body weight, the injection of as much as 26 mumol of phenylalanine was required for its concentration in plasma to be stil...

The plasma concentration of phenylalanine and tyrosine decreases in normal rats during the first few postnatal days; subsequently, the concentration of phenylalanine remains more or less constant, whereas that of tyrosine exhibits a high peak on day 13. The basal concentrations of the two amino acids were not altered by injections of thyroxine or cortisol, except in 13-day-old rats, when an inj...

The mode of action of the p-chlorophenylalanine in these animals is not clear. pChlorophenylalanine, in vitro, is not an appreciable inhibitor of phenylalanine hydroxylase, and this is apparently so in vivo also as the lowering of phenylalanine hydroxylase activity shows a delayed response to p-chlorophenylalanine treatment. However, the decrease in phenylalanine hydroxylase activity is not cau...

1. Plasma tyrosine and phenylalanine were measured in patients with chronic renal failure and in normal subjects. Plasma tyrosine to phenylalanine ratio was greatly decreased in patients with creatinine clearance less than 16 ml/min, suggesting an impairment of phenylalanine hydroxylation. This ratio correlated with the percentage of essential to total amino nitrogen in the plasma. 2. Phenylala...

Effects of phenylalanine and diand tetrahydropterins on presteady-state and steady-state catalytic behavior of rat liver phenylalanine hydroxylase are analyzed. From this and previous work (Shiman, R, Xia, T., Hill, M., and Gray, D. (1994) J. BioZ. Chem. 269, 2464724656), which analyzed binding of the same compounds to the enzyme in the absence of catalysis, a model of phenylalanine hydroxylase...

Buchnera aphidicola, the prokaryotic endosymbiont of aphids, complements dietary deficiencies with the synthesis and provision of several essential amino acids. We have cloned and sequenced a region of the genome of B. aphidicola isolated from Acyrthosiphon pisum which includes the two-domain aroQ/pheA gene. This gene encodes the bifunctional chorismate mutase-prephenate dehydratase protein, wh...

The biochemical features of phenylketonuria have been reproduced in developing rat pups by administering to them a combination of p-chloro-DL-phenylalanine plus L-phenylalanine for the first 21 days after birth. During the treatment period, the experimental animals show delayed eye opening and decreased brain weight compared with controls given saline. Neuropathological examination of developin...