Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Iodoacetylphenylalanyl-tRNAPhe was used as an affinity label to localize the ribosomal components involved in the peptidyl transferase catalytic center of Escherichia coli ribosomes. When labeling was carried out at pH 5.0, the affinity label could specifically label the ribosomal components which comprise the catalytic center. Analysis of ribosomal proteins which had reacted with the affinity label revealed that a 30 S subunit protein, S 20, was located at or near to the ribosomal binding site of the 3'-terminus of aminoacyl- or peptidyl-tRNA.
Mol Biol Rep 1975 Oct
PMID:Identification of the 30 S protein adjacent to peptidyl transferase catalytic center of Escherichia coli ribosomes. 0 Jun 11

Imidazole catalysis of phenylalanyl transfer from phenylalanine adenylate anhydride to the hydroxyl groups of homopolyribonucleotides was investigated as a chemical model of the biochemical aminoacylation of tRNA. Imidazole catalyzed transfer of phenylalanine to poly(U) increases from pH 6.5 to 7.7 and decreases above pH 7.7. At pH 7.7 approximately 10% of the phenylalanyl residues are transferred to poly(U). At pH 7.1, transfer to poly(U) was five times as great as to poly(A) and transfer to a poly(A) poly(U) double helix was negligible. At pH 7.1 approximately 45 mole percent linkages to poly(U) were monomeric phenylalanine; the remainder of the linkages were peptides of phenylalanine. The number of linkages and their lability to base and neutral hydroxylamine indicates that phenylalanine and its peptides are attached as esters to the 2' hydroxyl groups throughout poly(U) and the 2' (3') hydroxyl groups at the terminus of poly(U). These results do model the contemporary process of aminoacyl transfer to tRNA and continue to suggest that a histidine residue is in the active site of aminoacyl-tRNA-synthetases.
J Mol Evol 1975 Dec 29
PMID:Aminoacyl transfer from an adenylate anhydride to polyribonucleotides. 0 44

Kinetics of DNA alkylation with 2',3'-o-[N-2-chloroethyl-N-methylamino)benzylidene]uridine (UCHRCL), uridine-5'-methylphosphate (MepUCHRCL) and 4-(N-2-chloroethyl-N-methylamino)benzylamine (NH2CH2RCl) and kinetics of elimination of alkylated bases have been studied. Efficiency of DNA alkylation (p/s-ratio of rate constant of alkylation to the sum of rate constants of by-reactions of an active intermediate formed from the reagent) increases with an increase of the positive charge of the reagents as well as efficiency of tRNA alkylation. Alkylated bases are eliminated from DNA; rate of elimination depends on the structure of the reagent; it decreases in the series NH2CH2R- greater than greater than UCHR-greater than MepUCHR-. Bases alkylated by NH2CH2RCl and UCHRCl are eliminated from DNA during alkylation; therefore plots of DNA alkylation by NH2CH2RCl have a maximum. DNA alkylated by MepUCHRCl is rather stable; alkylated bases are not eliminated during alkylation. Effect of temperature and pH on elimination has been studied.
Mol Biol (Mosk)
PMID:[Kinetic characteristics of DNA alkylation with some chloroethylmethylarylamines and elimination of alkylated bases from DNA]. 0 60

Incubation of CMP in 2H2O with 0.5M cysteine methyl ester at p2H 5 and 37 degrees C for 24 h resulted in 43% exchange of 5-H to 5-2H. No deamination of the cytosine nucleus was noted during this treatment. Native and denatured DNA samples from calf thymus were treated in 3H2O with cysteine methyl ester at pH 5 and 37 degrees C for 24 h and incorporation of tritium into each DNA base was determined by enzymic digestion of the treated DNA. The order of the specific radioactivity found was cytosine greater than guanine greater than adenine greater than thymine for denatured DNA and guanine greater than adenine approximately cytosine greater than thymine for native DNA. The ratio of radioactivity for denatured/native was 11.6 for cytosine, 1.5 for guanine, 1.8 for adenine and 1.1 for thymine. Hence the incorporation in cytosine under the reaction conditions is preferential for single-stranded, nonhelical regions of DNA. Escherichia coli glutamic acid tRNA II was treated in 3H2O with 1.24 M cysteine methyl ester at pH 5 and 37 degrees C. The 24-h-treated tRNA was digested with ribonuclease T1 and the fragments were fractionated. Each fragment was then digested with ribonuclease T2 into mononucleotides and the radioactivity distribution among the bases was determined. The average radioactivity found for each of the bases of the four major nucleotides was cytosine greater than guanine approximately adenine greater than uracil. The radioactivity in cytosine varied greatly among the RNase T1 fragments, the ratio of the highest to the lowest radioactivity being 18.7. The corresponding value for guanine was 11.1, for adenine 4.73 and for uracil 3.64. Based on the data obtained, it was deduced that in this tRNA the anticodon loop, the dihydrouridine loop and the extra loop were "exposed" under the conditions employed for the labeling. The 5'-terminal cytosine of the anticodon loop was in a "non-exposed" state, a situation similar to that previously reported for E. coli tyrosine tRNA [Cashmore, A. R., Brown, D. M. & Smith, J. D. (1971) J. Mol. Biol. 59, 359-373] and for E. coli formylmethionine tRNA [Goddard J. P.+Schulman L. H. (1972) J. Biol. Chem. 247, 3864-3867]. Both cytosine 48, located at the 3'-terminal of the extra loop, and guanine 15 in the dihydrouridine loop were in an "emposed" state. This finding does not agree with a tRNA model in which this pair of cytosine and guanine, commonly found in tRNA sequences, forms hydrogen bondings. Positions 30--32, 61--64 and 71, which are located in the stems, were found to be strongly "buried".
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PMID:Conformation of Escherichia coli glutamic acid tRNA II as studied by hydrogen-tritium exchange catalyzed by cysteine methyl ester. 0 69

The equilibrium constant of a complex of tRNA with the 50S ribosomal subunit was measured in the absence of a template. It was shown that the stability of the complex increases with an increase in the concentration of Mg2+, it decreases with an increase in the concentration of univalent ions, and does not depend on the pH of the medium in the range of 7.0-8.2. Removal of the 3'-terminal nucleoside of tRNA weakens the association approximately 40-fold; the subsequent successive splitting off of another three nucleotides has little effect on the association constant. In 90% 2H2O the stability of the complex increases approximately four-fold, which points to the large contribution of the hydrogen bonds to the free energy of the interaction. The tetranucleotide TphiCG competes slightly with tRNA for sites on the 50S subparticles; this means that the TphiC segment of tRNA does not play an important role in the formation of the complex under investigation.
Mol Biol (Mosk)
PMID:Interaction of transfer RNA with 50S ribosomal subunits of Escherichia coli in absence of templates. 1 9

The reaction of aminoacylation of tRNAPhe from yeasts and the erroneous acylation of total tRNA from E. coli by yeast phenylalanyl-tRNA synthetase under special conditions was studied. It was shown that the decrease in the degree of acylation of tRNAPhe and the increase in the degree of erroneous acylation of the total tRNA from E. coli are associated with the influence of these conditions on the structure of tRNA, and not on the structure or specificity of the enzyme. It was found that under special conditions of acylation, tRNAPhe exists in two conformations: acylatable and nonacylatable. The ability for complete acylation is restored after the transfer of tRNAPhe under classical conditions of acylation. The results are discussed from the standpoint of possible mechanisms of the recognition of tRNA by aminoacyl-tRNA synthetases.
Mol Biol (Mosk)
PMID:Acceptor activity of tRNAPhe from yeasts under special conditions of aminoacylation. 1 12

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

We have synthesized 2'(3')-O-(glycyl)-adenosine-5'-(O-methylphosphate), an analogue of the 3'-terminus of aminoacylated tRNA. A 0.4M solution of this compound maintained at pH 8.2, yields 5.5% of diglycine and 11.5% of diketopiperazine, in addition to the hydrolysis products glycine and adenosine-5'-(O-methylphosphate). Under the same conditions, glycine ethyl ester reacts much more slowly, but ultimately gives similar yields of diglycine and diketopiperazine. The aminolysis of 2'(3')-O-(glycyl)-adenosine-5'-(O-methylphosphate) by free glycine is relatively inefficient, but serine reacts 20 times more rapidly and yields up to 50% of N-glycylserine. The prebiotic significance of these reactions is discussed.
J Mol Evol 1978 Aug 02
PMID:The formation of peptides from the 2'(3')-glycyl ester of a nucleotide. 2 32

A fraction of immunoglobulins was isolated from the sera of rabbit immunised by a homogeneous beef pancreas tryptophanyl-tRNA-synthetase (TRSase). The IgG fraction was shown to inhibit the enzymatic activity during aminoacylation of yeast tRNATrp and tryptophan activation. By using the radioimmunoadsorption technique, the interaction of IgG was tested with TRSaes from beef pancreas and identical enzymes from other sources (contained in the total preparation). Beef liver TRSase efficiently inhibited the radioimmunoadsorption reaction of beef pancrease 125J-TRSase that suggests a strong similarity or even identity of the enzymes. When the purified antibodies to beef pancreas TRSase were isolated common antigen determinants were revealed for TRSase from beef pancreas, liver of chick, pig and rat. Enzymatic activity of TRSase from liver of beef, pig and chick was shown to be inhibited by antibodies to beef pancreas. TRSase whereas the enzymes from rat liver and yeast did not change their activity in the presence of these antibodies. Therefore, for several TRAases common antigen determinants have been revealed that suggest the presence of common structural elements in these enzymes; antibody binding inhibits the activity of some TRSases and does not affect that of others.
Mol Biol (Mosk)
PMID:[Immunochemical comparison of tryptophanyl-tRNA-synthetases]. 7 39

Highly purified RNA dependent DNA-polymerase was isolated recently from E. coli by Romashchenko et al. [8]. The present data demonstrate that total E. coli tRNA inhibits poly(dT) synthesis on poly (A): oligo (dT) catalyzed by the enzyme when the enzyme:tRNA ratio is about 1 : 80--100. The inhibition results from the binding of certain tRNA's by the enzyme. The enzyme tRNA complex was separated from the unbound tRNA's by gel-filtration of Sephadex G-100. The tRNA's extracted from the complex are able to inhibit completely poly(A):oligo(dT) templated synthesis of poly(dT) under the enzyme:tRNA ratio about 1 : 2--3. Aminoacylation of tRNA separated from the enzyme complex has shown that E. coli RNA dependent DNA-polymerase selectively binds tRNAThr and to a lesser extent tRNATyr and tRNALys. It is suggested that the enzyme bound tRNA's carry out the functions of natural primers which compete with oligo(dT) for the enzyme responsible for the primer binding.
Mol Biol (Mosk)
PMID:[Selective binding of tRNA by RNA dependent DNA-polymerase from Escherichia coli]. 8 33


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