Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tyrosine contributions to the structure-function relationship in the fructose-1, 6-biphospate aldolase from C. capitata have been investigated. There are three well defined groups of tyrosine residues with different roles in the structure of the insect aldolase. C-terminal tyrosine residues are essential for the maintenance of the catalytic conformation. Releasing of these residues by carboxypeptidase A treatment results in complex conformational changes according to CD studies. Another tyrosine residue group is located at the active site, and the substrate, fructose-1, 6-biphosphate, protects it upon nitration. Chemical modification of this residue results in enzyme activity changes similar to those induced by carboxypeptidase digestion. Enzyme-substrate interaction results in a change of the microenvironment of at least three tyrosine residues per subunit with different accessibility for tetranitromethane.
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PMID:Role of tyrosine residues on structure-function of fructose-1,6-biphosphate aldolase from Ceratitis capitata. 711 91

An unusual type of posttranslational modification has been observed in a rat brain in vitro system. It consists in leucine addition to a preformed protein in such a way that the added leucine is not located at either the NH2 or the COOH terminus of the acceptor protein. The incorporation reaction requires ATP, ATP-generating components and tRNA. It is inhibited by aurintricarboxylic acid but does not require the presence of ribosomes or GTP. The incorporated leucine has a free NH2 group, and it is not released by leucine aminopeptidase or carboxypeptidase A. It is linked to the acceptor protein through a bond that is too alkali labile and too hydroxylamine labile to be a peptide bond. The simplest interpretation of the results consists in proposing that an ester bond is formed between the leucine and the side chain of a serine, threonine, or tyrosine in the acceptor protein.
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PMID:Transfer ribonucleic acid dependent but ribosome-independent leucine incorporation into rat brain protein. 717 78

Equilibrium sedimentation experiments of the native acid phosphatase indicate a dimer-tetramer dissociating nonequilibrating system with a dimer Mr = 180,000 g/mol. The hydrolysis of nitrophenylphosphate was used to determine the sedimentation coefficient of the active species. The s20,w value for the species which degrades nitrophenylphosphate is 13.52 +/- 0.46 S in 1% sucrose and 13.72 +/- 0.11 S in 1.3 M sodium chloride, corresponding to the Svedberg value of the tetramer species. Several lines of evidence are presented which, together with previous data, indicate that the Schizosaccharomyces pombe nonspecific acid phosphatase is composed of 4 identical or nearly identical polypeptide chains: a, equilibrium sedimentation analysis of the enzyme in denaturing agents indicates the presence of homogeneous material having Mr = 90,800 g/mol; b, digestion with carboxypeptidase A releases 0.82 mol of tyrosine/monomer molecular weight. Concomitant phosphatase inactivation occurred during the splitting off of the tyrosyl terminal residue. Furthermore, a unique NH2-terminal residue (histidine) was determined.
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PMID:Molecular properties and active form of nonspecific acid phosphatase from Schizosaccharomyces pombe. 721 63

Carboxypeptidase A gamma from porcine pancreas was purified to homogeneity by ammonium sulfate fractionation, autolysis, batch absorption and elution from DEAF-Sephadex, and crystallization. The overall purification was about 32-fold with a yield of 31% and the specific activity of the purified protein was 108 units/mg protein. The apparent relative molecular mass determined by gel filtration on a Sephadex G-200 column was 38 900. The amino-terminal sequence of the porcine carboxypeptidase A gamma was Asn-Tyr-Ala-Thr-Tyr-His-Thr-Leu-Glu-Glu-Ile-Tyr-Asp-Phe-Met-Asp-Ile-Leu-Val-Ala -Glu-His-Pro-Gln-Leu- which was highly homologous to that of bovine carboxypeptidase A gamma. The purified enzyme was characterized with respect to isoelectric point (4.3). Km for N alpha-carbobenzoxyglycyl-L-phenylalanine (Cbz-Gly-LPhe) (20 mM), amino acid composition, pH optimum, pH stability, stability at different temperatures and effect of drying. The enzyme contained 1.01 mol zinc/mol and was inhibited by chelating agents such as EDTA and o-phenanthroline. Among substrates such as Cbz-Gly-LPhe, N alpha-benzoylglycyl-L-arginine, various kinds of amino acid esters, casein and elastin, porcine carboxypeptidase A gamma showed an enzymatic activity only towards Cbz-Gly-LPhe and casein. These data are in good agreement with the substrate specificity of bovine carboxypeptidase A.
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PMID:Crystallization and properties of carboxypeptidase A gamma from porcine pancreas. 727 15

A carboxypeptidase A-like enzyme known as cathepsin A was purified from rat brain by extraction with Triton X-100, followed by chromatography on DEAE-Sephadex A-50 and gel-filtration. Purified enzyme was devoid of contamination of tryptic-like enzymes, by dipeptidyl carboxypeptidase (angiotensin converting enzyme) and of enkephalinnases cleaving the Tyr-Gly and Gly-Phe bonds of Met-enkephalin. Incubation of purified enzyme with Met-enkephalin-Arg6-Phe7, a naturally occurring enkephalin surrogate, was accompanied by the release of three products as detected by reverse phase HPLC. Subsequent amino acid analysis identified these as Phe, Met-enkephalin-Arg6, and Met-enkephalin, indicating cleavage at the Arg6-Phe7 and Met5-Phe6 bonds. Breakdown followed a precursor-product-relationship with the hexapeptide appearing as an intermediate and the pentapeptide as the final product. The Km for cleavage of the Arg-Phe site was 0.09 mM. Rates of cleavage of hexa- and heptapeptide accord with those found for synthetic N-protected dipeptide substrates. Cathepsin A does not act as an enkephalinase in the accepted sense, since no breakdown of Met-enkephalin was observed.
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PMID:Conversion of Met-enkephalin-Arg6-Phe7 by a purified brain carboxypeptidase (cathepsin A). 729 Oct 41

The involvement of two active site residues of carboxypeptidase A in binding a protein inhibitor from Ascaris was studied. Glu-270 was modified with N-ethyl-5-phenylisoxazolium-3'-sulfonate and Tyr-248 was modified with tetranitromethane or diazotized arsanilic acid. Modification of Glu-270 abolished protein inhibitor binding and Glu-270 was protected from modification when the enzyme was bound to the protein inhibitor. In contrast, modification of Tyr-248 did not abolish protein inhibitor binding, nor did such binding protect Tyr-248 from modification. The absorption isosbestic point of arsanilazocarboxypeptidase A (Tyr-248 chemically modified) underwent a blue shift from 428 to 416 nm when the modified enzyme was bound to the protein inhibitor between pH 7.7 and 9.0. The 416 nm isosbestic point is characteristic of the loss of interaction between modified Tyr-248 and the active site zinc ion. These results with a protein inhibitor can be compared to substrate catalysis in which Tyr-248 moves away from the active site zinc ion of carboxypeptidase A when substrate binds. The close association of Glu-270 with Ascaris inhibitor interaction is consistent with other results which show that of the active site residues, only the modification of Glu-270 completely abolishes catalysis.
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PMID:Modification of the carboxypeptidase A active site residue Glu-270 prevents interaction with a protein protease inhibitor from Ascaris. 737 Feb 77

The antitubercular drug isoniazid (INH) was hown by radio-chromatographic studies to react with tyrosine in growth medium. Exogenous tyrosine added to the growth medium interfered with the inhibitory action of INH on Mycobacterium phlei. These observations were confirmed by difference spectra studies which showed that tyrosine would react with INH as long as the tyrosine phenolic hydroxyl group was not blocked. These results led to the hypothesis that INH could exert its influence by interfering with tyrosine residues in mycobacterial proteins. N-acetylimidazole, a tyrosine-acetylating agent, mimicked the action of INH on the reduced nicotinamide adenine dinucleotide oxidase and dehydrogenase activity in electron transport particles from wild-type and INH-resistant M. phlei. Pyrazinamide, a drug structurally related to INH, also mimicked its effect on electron transport particles. To confirm that INH could react with tyrosine in proteins, purified enzymes with known tyrosine positions were tested. Bovine carboxypeptidase A with tyrosine at the active site was inhibited by INH and N-acetylimidazole, whereas the controls, yeast alcohol dehydrogenase and ribonuclease A, were not. It is therefore proposed that tyrosine residues in proteins may serve as the target for INH action in mycobacteria.
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PMID:Isoniazid interaction with tyrosine as a possible mode of action of the drug in mycobacteria. 738 39

The amount of total tubulin in the soluble fraction of rat brain was measured by a method based on the purification of tubulin previously labeled by incorporation of [14C]tyrosine in the C terminus of its alpha-chain. The tubulin content decreased from 2.01 to 1.30 nmol/mg protein when the animals passed from 4 to 30 days of age and then remained practically constant. The amounts of aminoacylated and non-aminoacylated tubulin present in the soluble brain extracts were determined from the incorporation of [14C]tyrosine into the free acceptor sites of tubulin preparations, that were preincubated without carboxypeptidase A or with this enzyme to eliminate tyrosine and phenylalanine from the C terminus of the alpha-chain of tubulin. The values obtained were corrected for the inactivation of tubulin to accept [14C]tyrosine that occurred during the isolation and incubation of the soluble fractions. The ratio non-aminoacylated/aminoacylated tubulin increased from 1.62 +/- 0.03 in the 4-day-old rats to 2.11 +/- 0.17 in the 120-day-old rats. The aminoacylatable tubulin, that is the sum of aminoacylated plus non-aminoacylated tubulin, decreased from 1.71 to 0.75 nmol/mg protein from 4-day-old to 30-day-old rats respectively and then remained practically constant. The amount of aminoacylatable tubulin is lower than that of total soluble tubulin. Therefore there is a fraction of tubulin that is unable to accept tyrosine. This non-aminoacylatable tubulin fraction increases with the age of the animal so that in the 120-day-old rats this tubulin species accounts for 48% of the total soluble tubulin.
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PMID:Total tubulin and its aminoacylated and non-aminoacylated forms during the development of rat brain. 740 95

Semi-empirical calculations of conformational properties of acetyl-L-tyrosine, glycyl-L-tyrosine, acetyl-L-alanyl-L-tyrosine and acetyl-L-alanyl-L-alanyl-tyrosine and their noncovalent complexes with carboxypeptidase A (CPA) are presented. Each of these molecules binds in the active site of CPA by only one binding mode. The substrates are practically free of intramolecular tension. It is shown that the binding of an aromatic side chain of a C-terminal residue of substrate provides productive orientation of the susceptible peptide bond. The sterochemical aspects of the interactions of Tyr-248 and Glu-270 residues with the substrates are considered.
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PMID:[Theoretical conformational analysis of noinvalent carboxypeptidase A complexes with inhibitors and substrates]. 742 20

Tubulin tyrosine ligase catalyzes the reversible addition of tyrosine to the C-terminus of tubulin alpha chains. By using ligase and carboxypeptidase A in conjunction, we have previously shown that brain cytoplasmic tubulin exists in three forms: 15-40% already has C-terminal tyrosine, another 10-30% can accept additional tyrosine, and about one-half is an uncharacterized species which is not a ligase substrate. A membrane-bound fraction of brain tubulin, purified by vinblastine precipitation from a detergent extract, has been found to differ by the complete absence of preexisting tyrosine. The membrane fraction from which tubulin was extracted also contained masked forms of both ligase and a distinct detyrosylating enzyme, which can be released by detergent extraction. The turnover of alpha-chain C-terminal tyrosine in vivo was studied by incubating brain mince with labeled tyrosine, or injecting it intracerebrally, under conditions where protein synthesis was inhibited. Tyrosine appeared to turn over to about the same extent in membrane-bound, as in soluble, tubulin. This apparently paradoxical result was not due to ATPase in the membrane fraction, which might have allowed ligase-catalyzed exchange between free and fixed tyrosine. Authentic [14C]tyrosylated tubulin added to the brain membrane fraction was not detyrosylated or subject to endoprotease digestion during subsequent procedures to isolate tubulin. The unexpected finding that tubulin tyrosylated at the C-terminal in vivo appears to be in the "non-substrate" fraction points toward a possible resolution of the paradox.
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PMID:An apparent paradox in the occurrence, and the in vivo turnover, of C-terminal tyrosine in membrane-bound tubulin of brain. 745 80


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