The three isozymes of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase from Escherichia coli were overproduced, purified, and characterized with respect to their requirement for metal cofactor. The isolated isozymes contained 0.2-0.3 mol of iron/mol of enzyme monomer, variable amounts of zinc, and traces of copper. Enzymatic activity of the native enzymes was stimulated 3-4-fold by the addi...

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...

Expired 13CO2 recovery from an oral l-[1-13C]phenylalanine ([13C]Phe) dose has been used to quantify liver function. This parameter, however, does not depend solely on liver function but also on total CO2 production, Phe turnover, and initial tracer distribution. Therefore, we evaluated the impact of these factors on breath test values. Nine ethyl-toxic cirrhotic patients and nine control subje...

Tyrosine (Tyr) is an essential amino acid in phenylketonuria (PKU) because of the limited hydroxylation of phenylalanine (Phe) to Tyr. The recommended intakes for Tyr in PKU are at least five times the recommended phenylalanine intakes. This suggests that Phe and Tyr contribute approximately 20 and 80%, respectively, of the aromatic amino acid (AAA) requirement (REQ). In animals and normal huma...

BACKGROUND L-phenylalanine (L-Phe) is an essential amino acid for mammals and applications expand into human health and nutritional products. In this study, a system level engineering was conducted to enhance L-Phe biosynthesis in Escherichia coli. RESULTS We inactivated the PTS system and recruited glucose uptake via combinatorial modulation of galP and glk to increase PEP supply in the Xllp...

We reported (Twyman, R. E., Gahring, L. C., Speiss, J., and Rogers, S. W. (1995) Neuron 14, 755-762) that antibodies to a subregion of the glutamate receptor (GluR) subunit GluR3 termed GluR3B (amino acids 372-395), act as highly specific GluR agonists. In this study we produced additional rabbit anti-GluR3B-specific antibodies, ranked them according to their ability to function as GluR agonist...

BACKGROUND To prevent cognitive impairment, phenylketonuria requires lifelong management of blood phenylalanine (Phe) concentration with a low-Phe diet. The diet restricts intake of Phe from natural proteins in combination with traditional amino acid medical foods (AA-MFs) or glycomacropeptide medical foods (GMP-MFs) that contain primarily intact protein and a small amount of Phe. OBJECTIVE W...

Two kinds of 3-deoxy-D-arabino-hepturosonate-7-phosphate (DAHP) synthase genes were cloned from an L-Phe-producing mutant of Brevibacterium lactofermentum, AJ11957, which was resistant to m-fluoro-D,L-phenylalanine (mFP) and p-fluoro-D,L-phenylalanine (pFP) and which had DAHP synthase free from feedback inhibition. Both genes were cloned using a vector plasmid, pAJ1844, and the resulting recomb...

This study was aimed to determine the effects of different concentrations L-phenylalanine (0.25, 0.50 and 1.00 mM L-Phe) applied adventitious root cultures for culture durations on growth production tropane alkaloids phenolics in Hyoscyamus niger. For this purpose, roots obtained from petiole explants vitro seedlings were used as plant materials. After cultured liquid Murashige Skoog (MS) mediu...

After COVID-19, patients have reported various complaints such as fatigue, neurological symptoms, and insomnia. Immune-mediated changes in amino acid metabolism might contribute to the development of these symptoms. Patients who had acute, PCR-confirmed COVID-19 infection about 60 days earlier were recruited within scope prospective CovILD study. We determined inflammatory parameters alteration...