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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Kinetic studies have been performed on the "family" of aminoacyl synthetases from calf liver. All assays were based on the esterification of amino acids to tRNA. Optimized reaction conditions for each synthetase are reported. Most of the synthetases show hyperbolic kinetics with respect to both amino acid and tRNA concentration, however a few show sigmoidal kinetics with respect to one substrate. Arginine, methionine and proline synthetases show sigmoidal kinetics with respect to mixed tRNA solutions and have Hill coefficients of 1.30, 1.10 and 1.20 respectively. Alanine and isoleucine synthetases show sigmoidal kinetics with respect to amino acid concentration and have Hill coefficients of 1.21 and 1.40 respectively.
Mol Cell Biochem 1977 Aug 19
PMID:Aminoacyl-tRNA synthetases from calf liver: optimized assay conditions and kinetic properties. 2 May 69

Specific modification of the monomeric fraction III of ferri-hemoglobin from insect larvae Chironomus thummi thummi (Hb CTT) was studied on histidyl residues His-G19 (pK 4,8), His-E5 (pK 7,3) and Met-H22 at different pH using iodacetamide and spin label 2,2,6,6-tetramethyl-4-bromacethyl-piperidin-1-oxyl, an analogue of bromacetate. The analysis of the products of carboxymethylation (CM) showed that at pH 5,0 two products of modification CM-(His-G19)-Hb CTT, and CM-(Met-H22)-Hb CTT were obtained. In the case of modification at pH 7,2 with a spin label dicarboxymethylatid product CM-(His-G19)-CM (His-E5)-Hb CTT is obtained. In all products the degree of modification was one spin label per mole protein. Based on the data on the primery and tertiary structures Hb CTT and the results of the investigation, different reactivity of His-G19 and His-E5, as well as the cause of the absence of the product of carboxymethylation on His-G2 have been discussed. By analizing the absorption spectra of carboxymethylated derivatives of hemoglobin in the ultraviolet and visible region, as well as from the pH dependence curves of the absorption at Soret band in the interval pH 5,5-11,5 it has been shown that carboxymethylation of His-G19 and His E5 is not accompanied by any substantial disturbance of the structures of aquous-complexes Hb CTT. Modification of Met-H22 leads to strong changes in the absorption spectrum and to the absence of pH dependence of the absorption at Soret band, which indicates a change in the aquous-complexes Hb CTT structure.
Mol Biol (Mosk)
PMID:[Selected carboxymethylation of ferri-hemoglobin from insect larvae Chironomus thummi thummi]. 17 63

1. The human adenoviruses types 2, 5 and 12 code for the production of a single strand specific DNA binding protein. The molecular weights of these proteins were 72,000 for types 2 and 5 and 60,000 for type 12. In all three cases proteolytic breakdown fragments of these binding proteins (48,000 MW) were also observed. 2. Analysis of the methionine containing tryptic peptides of these proteins indicate that the types 2 and 5 proteins are similar and clearly distinguishable from the type 12 protein. The peptide maps of these three viral proteins are clearly different from a similar protein found in mock infected cells. 3. Temperature sensitive mutants of type 5 (H5ts125) and type 12(H12tsA275) adenoviruses fail to produce these proteins at the nonpermissive temperature. H5ts125 infected cells grown at the permissive temperature produce a 72,000 MW protein that is thermolabile, for continued binding to DNA, when compared to type 5 wild type adenovirus 72,000 MW protein. An analysis of the phenotype of this adenovirus mutant indicates that it codes for a viral function at early times after infection that is required for viral DNA replication. 4. The in vitro translation of adenovirus specific m-RNA results in the synthesis of a small amount of a 72,000 MW protein that binds to single stranded DNA just like the authentic adenovirus DNA binding proteins produced in infected cells. 5. Adenovirus anti-Tumor antigen (T) anti-serum from hamsters carrying independently derived adenovirus tumors, have been tested for the presence of antibody to purified DNA binding proteins. One antiserum is positive for these antibodies while the other is negative. These results indicate that some, but not all, adenovirus tumors contain large enough levels of the DNA binding proteins to elicit an antibody response. 6. The type 5 adenovirus temperature sensitive mutant, H5ts125, that codes for a thermolabile DNA binding protein, was complemented or suppressed at the nonpermissive temperature, for the replication of adenovirus DNA, by SV40. SV40tsA temperature sensitive mutants, defective in SV40 DNA replication, do not suppress or complement H5ts125 at the nonpermissive temperature.
Mol Cell Biochem 1976 Apr 28
PMID:Characterization of an adenovirus early protein required for viral DNA replication: a single strand specific DNA binding proteins. 17 93

Native dimeric methionyl-tRNA synthetase and its monomeric proteolytic fragment are shown to form and to bind 1 mol of methyionyl adenylate per polypeptide chain. Moreover, at 25 degrees C, each monomer of the dimeric native enzyme behaves independently, exhibiting the same parameters for the methionine activation reaction as does the monomeric modified enzyme. These results were obtained using several independent methods including equilibrium and nonequilibrium dialysis, active site and tryptophan fluorescence titrations, and stopped-flow by fluorescence. Stopped-flow resolution of the reversible methionine activation reaction also demonstrates that methionine and ATP-Mg2+ react without coupling to form a ternary enzyme-methionine-ATP-Mg2+ complex. This complex readily converts to enzyme-methionyl approximately adenylate-PP-Mg2+ with a standard free energy close to zero. It is concluded that the uncoupled enzyme-methionine-ATP-Mg2+ complex may resemble the transition state of the reaction at the expense of the additional state of the reaction at the expense of the additional synergistic binding energy provided by reciprocal coupling, within the site, of the methionine molecule with the adenosine and PP-Mg2+ parts of the ATP-Mg2+ molecule (Blanguet, S., Fayat, G., and Waller, J. P. (1975), J. Mol. Biol. 94, 1.).
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PMID:Methionyl-tRNA synthetase from Escherichia coli: active stoichiometry and stopped-flow analysis of methionyl adenylate formaiton. 18 14

Serratia marcescens Sa-3 possesses two homoserine dehydrogenases and neither has any aspartokinase activity unlike the case of Escherichia coli enzymes. The two enzymes have been separated. One of them is active with either NAD+ or NADP+ and has been purified about 180-fold to homogeneity. This enzyme is completely repressed by the presence of 1 mM methionine or homoserine in the growth medium, but its activity is unaffected by any amino acid of the aspartate family either singly or together. In many of its properties (such as pH optimum, Km for substrate and cofactors), it resembles its counterpart in E. coli K12. Potassium ions stabilize the enzyme but are not essential for activity. Its molecular weight is around 155,000 as determined by gel filtration and approximately 76,000 by SDS-polyacrylamide gel electrophoresis. This suggests that the enzyme has two subunits (polypeptide chains) in the molecule: 8 M urea has no effect on enzyme activity. This enzyme represents approximately 30% of the total homoserine dehydrogenase activity of S. marcescens unlike in Salmonella typhimurium and E. coli K12 where it is a minor or a negligible component.
Mol Cell Biochem 1976 Jul 30
PMID:Methionine-repressible homoserine dehydrogenase of Serratia marcescens: purification and properties. 18 74

High molecular weight RNA (35S) isolated from avian myeloblastosis virus directs the cell-free synthesis of two prominent polypeptides of 180,000 and 76,000 molecular weight. The latter polypeptide has previously been identified as the precursor to the group-specific antigens of the virus ("gag" proteins) [Vogt, V. M., Eisenman, R. & Diggelmann, H. (1975) J. Mol. Biol. 96, 471-493]. Two-dimensional tryptic peptide analyses of the [35S]methionine-labeled peptides demonstrate that the 180,000-dalton product is a polyprotein that can account for all the peptides of the avian myeloblastosis virus DNA polymerase (DNA nucleotidyltransferase, EC 2.7.7.7) and those of the gag viral proteins. This is direct confirmation of the genomic order of the viral structural genes, placing the polymerase gene adjacent to the 5'-proximal gag gene of the virus. Furthermore, our findings suggest that the primary polymerase gene product is the beta subunit of the enzyme. These results are discussed in relation to the proposed structural gene map for the avian retraviruses and suggest a model for the in vivo processing of the viral polymerase.
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PMID:Cell-free synthesis of the precursor polypeptide for avian myeloblastosis virus DNA polymerase. 20 Sep 40

1. The cardiovascular effects of enkephalins have been tested in normotensive Wistar-Kyoto rats. Methionine-enkephalin and leucine-enkephalin increased blood pressure and heart rate after infusion into the brain ventricles. 2. After intravenous injection, blood pressure was increased by methionine-enkephalin and leucine-enkephalin, but heart rate was increased by methionine-enkephalin only. 3. Propranolol treatment reduced the increases in blood pressure following intraventricular methionine-enkephalin and leucine-enkephalin, while only the methionine-enkephalin-induced increases in heart rate were reduced by propranolol. 4. Heart rate and blood pressure responses after intravenous administration of methionine-enkephalins and leucine-enkephalin were not affected by propranolol. 5. Since opioid peptides occur in the blood and in regions of the brain involved in blood pressure regulation, the demonstrated cardiovascular effects to intraventricular and intravenous enkephalins support a role of these peptides in central and peripheral mechanisms of blood pressure control.
Clin Sci Mol Med Suppl 1978 Dec
PMID:Effects of enkephalins on arterial blood pressure are reduced by propranolol. 28 60

ATP-sulfurylase, cysteine synthase, homocysteine synthase, arylsulfatase and beta-cystathionase in Saccharomycopsis lipolytica are repressed on the addition of methionine, homocysteine or cysteine to the growth medium. The use of appropriate mutants enabled us to demonstrate that the synthesis of these enzymes is regulated by the system involving at least two low-molecular weight effectors--most likely cysteine and methionine (or their close derivatives).
Mol Gen Genet 1979 Jul 02
PMID:Regulation of s-amino acids biosynthesis in Saccharomycopsis lipolytica. 28 1

A genetic method was devised to test the hypothesis that in some cysteine or methionine requiring (cym) mutants of Salmonella typhimurium suppression of auxotrophy is due to an insertion at the site of the cym mutation. It was found that suppressed strains have an insertion of about 9kb in the cysCDHIJ region and that in unstable suppressed strains it is the instability of this insertion which results in the segregation of cym auxotrophs.
Mol Gen Genet 1977 Nov 18
PMID:The structure of the cysCDHIJ region in unstable cysteine or methionine requiring mutants of Salmonella typhimurium. 34 Sep 11

Enhancement of the nuclear relaxation rates by manganese has been used to derive manganese--purine-ring distances in the activation site of methionyl-tRNA synthetase. This is possible with the help of an abortive complex between the enzyme, methionine, adenosine, pyrophosphate and manganese which simulates an intermediate species of the activation reaction. It is found that the distances between the manganese ion and the purine ring are too high (greater than 0.8 nm) to allow interaction between them. Thus, metal-purine interaction is involved neither in the catalytic mechanism nor in the stabilization of abortive synergistic complexes [S. Blanquet, G. Fayat and J. P. Waller (1975) J. Mol. Biol. 94, 1-15].
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PMID:Methionyl-tRNA synthetase from Escherichia coli. Absence of interaction between the metal ion and the purine ring of ATP in the L-methionine activation site. 34 71


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