Phenylalanine ammonia-lyase, which irreversibly deaminates phenylalanine and tyrosine, markedly inhibited the growth of human leukemic and murine L5178Y lymphoblasts in vitro but had a negligible effect on resting (nondividing) normal lymphocytes. These studies also demonstrated that phenylalanine ammonia-lyase inhibited DNA synthesis in leukemic cells at least as effectively as did asparaginas...

Phenylpyruvic acid (PPA) is widely used in the pharmaceutical, food, and chemical industries. Here, a two-step bioconversion process, involving growing and resting cells, was established to produce PPA from l-phenylalanine using the engineered Escherichia coli constructed previously. First, the biotransformation conditions for growing cells were optimized (l-phenylalanine concentration 20.0 g·L...

The tissue kallikrein inhibitors reported in the present work were derived by selectively replacing residues in Nalpha-substituted arginine- or phenylalanine-pNA (where pNA is p-nitroanilide), and in peptide substrates for these enzymes. Phenylacetyl-Arg-pNA was found to be an efficient inhibitor of human tissue kallikrein (Ki 0.4 microM) and was neither a substrate nor an inhibitor of plasma k...

Acute dietary tyrosine depletion has previously been shown to reduce dopamine neurotransmission in both animals and humans. In this study, we investigated the effects of brain dopamine depletion, through acute tyrosine and phenylalanine depletion, on plasma prolactin, mood and neuropsychological function in 12 normal subjects. In a randomized, double-blind, cross-over design, subjects received ...

The aromatic amino acids are synthesized via a common biosynthetic pathway. A tryptophan-producing mutant of Corynebacterium glutamicum was genetically engineered to produce tyrosine or phenylalanine in abundance. To achieve this, three biosynthetic genes encoding the first enzyme in the common pathway, 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DS), and the branch-point enzymes chor...

Five rhesus monkeys were infused intravenously with partially purified cholecystokinin (CCK) Just prior to a test meal of solid food after overnight food deprivation; CCK produced large, rapid, dose related suppressions of feeding. The lowest dose tested (5 Ivy U/kg body wt) produced a significant inhibition of food intake (26% suppression, P less than 0.05). Equivalent infusions of partially p...

Self-assembly of phenylalanine is linked to amyloid formation toxicity in phenylketonuria disease. We are demonstrating that L-phenylalanine self-assembles to amyloid fibrils at varying experimental conditions and transforms to a gel state at saturated concentration. Biophysical methods including nuclear magnetic resonance, resistance by alpha-phenylglycine to fibril formation and preference of...

Phenylketonuria is the most prevalent disorder caused by an inborn error in aminoacid metabolism. It results from mutations in the phenylalanine hydroxylase gene. Phenotypes can vary from a very mild increase in blood phenylalanine concentrations to a severe classic phenotype with pronounced hyperphenylalaninaemia, which, if untreated, results in profound and irreversible mental disability. Neo...

The main question in this paper was to look at the distribution of auxotypes and serovars of Neisseria gonorrhoeae and check whether they correlate with clinical symptoms/signs among female sex workers (FSW) from Kinshasa, Zaïre. The subject were 1233 FSW enrolled in a cross sectional study on STDs and HIV infection in 1988; 771 of them were followed prospectively for a median duration of 23 mo...

Phenylalanine ammonia-lyase, which irreversibly deaminates phenylalanine and tyrosine, markedly inhibited the growth of human leukemic and murine L5178Y lymphoblasts in vitro but had a negligible effect on resting (nondividing) normal lymphocytes. These studies also demonstrated that phenylalanine ammonia-lyase inhibited DNA synthesis in leukemic cells at least as effectively as did asparaginas...