The interaction of a series of derivatives of tyrosine with horseradish peroxidase (HRP) and lactoperoxidase (LPO) was studied by using optical difference spectroscopy, c.d. and proton n.m.r. spectroscopy in order to reveal differences in the mode of binding of L-tyrosine and D-tyrosine, which are substrates of but react at different rates with the two peroxidases, to HRP and LPO. All the donor...

INTRODUCTION High expression of the system L amino acid transporter has been observed in clinically important tissues including tumors and the blood-brain barrier. We examined amino acid transport system L selectivity of (14)C(U)-L-tyrosine ((14)C-Tyr), (125)I-4-iodo-L-meta-tyrosine (4-(125)I-mTyr), (125)I-6-iodo-L-meta-tyrosine (6-(125)I-mTyr), (125)I-3-iodo-α-methyl-L-tyrosine ((125)I-IMT) an...

The subject of this literature review is the alleged relationship between L-tyrosine, phenelzine, and hypertensive crisis. Phenelzine (Nardil(®)) prescribing information notes: "The potentiation of sympathomimetic substances and related compounds by MAO inhibitors may result in hypertensive crises (see WARNINGS). Therefore, patients being treated with NARDIL should not take […] L-tyrosine […]"....

The weanling pig's requirement for total dietary aromatic amino acids (TAAA) and the portion of this requirement that can be efficiently provided by tyrosine were studied. An amino acid-fortified corn diet that was firstlimiting in TAAA was used in all feeding trials. Chick and microbiological growth assays established that the corn contained. 31% bioavailable phenylalanine and .48% bioavailabl...

Wild-type Brevibacterium flavum has been shown to possess arogenate dehydrogenase activity and to lack prephenate dehydrogenase, thereby providing presumptive evidence that arogenate (previously named "pretyrosine") is an obligatory intermediate of L-tyrosine biosynthesis. A similar enzymological pattern has been discerned in extracts made from wild-type cultures of various species of cyanobact...

Phagocytes secrete the heme protein myeloperoxidase, which is present and active in human atherosclerotic tissue. These cells also generate hydrogen peroxide (H2O2), thereby allowing myeloperoxidase to generate a range of oxidizing intermediates and stable end products. When this system acts on L-tyrosine in vitro, it forms o, o'-dityrosine, which is enriched in atherosclerotic lesions. Myelope...

-Tyrosinase, tryptophanase and cysteine desulfhydrase were shown to catalyze a variety of a,—elimination, s—replacement and the reverse of the ct,—elimination reactions of amino acids. The mechanism f or these reactions was studied using the general mechanism for pyridoxal— dependent reactions. The enzyme—bound n—amino acrylate is the key intermediate. Enzymatic methods for preparing L—tyrosine...

Incubation of pheochromocytoma cells with 56 mM K+ or with cholera toxin increases the conversion of [14C]tyrosine to [14C]catecholamines (Chalfie, M., Settipani, L., and Perlman, R. L. (1979) Mol. Pharmacol. 15, 263-270). We have now measured the tyrosine content and the rate of dihydroxyphenylalanine production in these cells. Incubation with 56 mM K+ or with cholera toxin increases the rate ...

Of the L and D configurations of four amino acids (phenylalanine, valine, tryptophan, tyrosine) tested for influence on the growth rate of Tetrahymena, only L-tyrosine was able to induce imprinting in Tetrahymena pyriformis Zeuthen. D-valine stimulated the division of T.pyriformis NT-1, but failed to induce imprinting. The experiments have substantiated the selectivity of the amino acid recepto...

l-DOPA is a major drug for the treatment of Parkinson’s disease, and microbial enzymatic synthesis an essential way its industrial production. The expression tyrosine phenol-lyase (TPL) derived from Erwinia herbicola under six different constitutive promoters in Escherichia coli was studied. recombinant strain 5 can express TPL well with growth. optimal medium composition this as follows: trypt...