Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aromatic amino acid aminotransferase was purified to a homogenous state from a gramicidin S-producing strain of Bacillus brevis. The enzyme shows a molecular weight of about 71,000 on gel-filtration. The subunit molecular weight is about 35,000 as determined by sodium dodecyl sulfate gel electrophoresis, indicating that the enzyme is a dimer. The enzyme exhibits absorption maxima near 425 and 330 nm at neutral pH. One mole of pyridoxal phosphate is bound per subunit. The enzyme has amino donor specificity for aromatic amino acids, L-phenylalanine, L-tyrosine, and L-tryptophan, and utilizes 2-oxoglutarate as the amino acceptor. This enzyme activity was separated from both the aspartate aminotransferase activity and the branched chain amino acid aminotransferase activity by chromatography on DEAE-Sephadex.
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PMID:Purification and properties of the aromatic amino acid aminotransferase from gramicidin S-producing Bacillus brevis. 244 Aug 56

A suppressor factor (TsF) specific for the synthetic terpolymer L-glutamic acid60-L-alanine30-L-tyrosine 10(GAT) produced by the T cell hybridoma 342B1.11 has been purified to apparent chemical homogeneity. This TsF was found in the cell culture supernatant, was associated with the cell membrane fraction, and was found in the cytosol. The supernatant form of TsF occurs as a single polypeptide chain of 29 to 30 k m.w., which easily forms aggregates of 65 k m.w. The membrane-associated form of TsF exists primarily as 65 k m.w., the cytosol TsF exists as both 65 and 29 to 30 k m.w. Amino acid analysis of each source of TsF shows the identical mole percent of amino acids, suggesting that all forms of TsF are derived from a single peptide of 29-30 k m.w. Analysis of the supernatant TsF by electroblot with the use of the anti-I-Js antisera (H-2s is the haplotype of the spleen cell donor) indicates that the polypeptide bears an I-J determinant, as do other TsF of this type.
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PMID:Purification and biochemical analysis of antigen-specific suppressor factors obtained from the supernatant, membrane, or cytosol of a T cell hybridoma. 619 3

In many laboratories, culturing skin melanocytes has become a routine research activity. However, recent investigations have revealed that the quality and quantity of the pigment formed in the cultured cells may differ significantly from those of the original skin pigment cells. To shed more light on this issue, we examined the influence of different culture media on pigment production. We showed that there were notable passage-to-passage variations in the synthesis of melanin. This was particularly true for phaeomelanin. It is therefore advisable to analyse the melanin in the cells before the start of experiments. In spite of the variations, basic differences in the pigmentation pattern between melanocytes isolated from light-skinned and dark-skinned individuals remained preserved in the corresponding cultures as observed by electron microscopy. Also, the total melanin content was higher in a skin type VI melanocyte culture than in skin type I and II melanocyte cultures. In contrast to total melanin, the phaeomelanin concentration of skin type VI cells was similar to that of the skin type I melanocytes. With higher L-tyrosine concentrations in the medium, as well as increased eumelanin synthesis, phaeomelanogenesis was also stimulated in all cultures tested. This stimulation was particularly prominent in skin type I melanocytes. Our preliminary experiments also showed that a melanocyte culture from atypical naevus cells exhibited a similar preference for phaeomelanogenesis when pigmentation was stimulated.
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PMID:Variations in melanin formation by cultured melanocytes from different skin types. 970 67

Phosphatase I purified from a psychrophile (Shewanella sp.) [Tsuruta et al. (1998) J. Biochem. 123, 219-225] dephosphorylated O-phospho-L-tyrosine and phospho-tyrosyl residues in phosphorylated poly(Glu4,Tyr1) random polymer (polyEY) and phosphorylated myelin basic protein (MBP) but not phosphoseryl and/or phosphothreonyl residues in phosphorylated histone H1, casein and phosphorylase a, indicating that the enzyme showed protein-tyrosine-phosphatase (PTPase, EC 3.1.3.48)-like activity in vitro. The enzyme was remarkably inhibited by diethylpyrocarbonate (DEPC), monoiodoacetic acid (MIAA), and monoiodoacetamide (MIAM). Binding of 1 mol of DEPC to 1 mol of the enzyme caused complete inhibition of the enzyme; and 0.88 mol of 1-carboxymethylated histidine per mole of the enzyme was found when 90% of enzyme activity was lost by modification with 14C-MIAA. These results indicated that this psychrophilic enzyme was a PTPase-like enzyme with histidine as its catalytic residue.
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PMID:Enzymatical properties of psychrophilic phosphatase I. 1010 Dec 81

The goal of this investigation was to correlate the melanin content in human pigmentary cells with the generation of UVB-induced photoproducts and to examine the relationship between the melanin content and the removal of the photoproducts. Cultured melanocytes from light-skinned individuals synthesized less melanin and produced more cyclobutane pyrimidine dimers and 6-4 photoproducts upon UVB exposure than did melanocytes from black skin. Tyrosine-stimulated melanogenesis provided protection against DNA damage in both cell types. In another set of pigmented cell lines a ratio between eumelanin and pheomelanin was determined. The assessment of association between DNA damage induction and the quantity and quality of melanin revealed that eumelanin concentration correlated better with DNA protection than pheomelanin. Skin type-I and skin type-VI melanocytes, congenital nevus (CN)-derived cells and skin type-II melanocytes from a multiple-melanoma patient were grown in media with low or high L-tyrosine concentration. The cells were irradiated with 200 J/m2 UVB, and the levels of the photoproducts were determined immediately and after 6 and 24 h. Once again the induction of the photoproducts was mitigated by increased melanogenesis, and it was inversely correlated with the skin type. No significant differences were found for the removal of photoproducts in the cultures of skin types I and VI and CN cells. No indications of a delay in the removal of photoproducts in the melanocytes from the multiple-melanoma patient were found either.
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PMID:Melanin offers protection against induction of cyclobutane pyrimidine dimers and 6-4 photoproducts by UVB in cultured human melanocytes. 1159 56

Dilept (GZR-123, N-caproyl-L-prolyl-L-tyrosine methyl ester), designed and synthesized at the Zakusov Institute of Pharmacology, was chosen as one of the most effective compounds from a series of N-acylprolyltyrosine derivatives having common pharmacophores with beta-turn of neurotensin (NT(8-13)) and repeating the structure of a nonpeptide prototype, the atypical neuroleptic sulpiride. The aim of this study was to evaluate the effect of dilept on the level of spontaneous and K(+)-stimulated release of glutamate. The experiments were performed in vitro on the cortical brain slices of male Wistar rats. Dilept used in concentrations 10(-5) and 10(-6) mole/liter did not affect the spontaneous release of glutamate though markedly decreased the K(+)-stimulated release. A decrease in the glutamate release under the action of the neuroleptic could contribute to the neuroprotective activity of dilept.
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PMID:[Decrease in the glutamate release may contribute to the neuroprotective action of the novel neuroleptic drug dilept]. 1765 Jun 23

On the occasions when D-tyrosine is observed to crystallize faster than its L-enantiomer, it is the result of a diastereomeric interaction between an airborne, non-racemic, chiral influence--probably a fungal spore--and the tyrosine enantiomers, enhancing the degree of crystal nucleation of D-tyrosine over L-tyrosine. This explanation, supported by experimental evidence, is presented as a more plausible alternative to the Shinitzky-Deamer hypothesis (Shinitzky et al., Progress in biological chirality, Elsevier, Amsterdam, pp. 329-337, 2004; Deamer et al., Chirality, 19:751-763, 2007) which relies on the parity violation energy difference between enantiomers, a femtojoule to picojoule per mole theoretical energy range.
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PMID:Experimental evidence leading to an alternative explanation of why D-tyrosine sometimes crystallizes faster than its L-enantiomer. 1821 86