Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.8 (polynucleotide phosphorylase)
 723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interaction of pyridoxal, pyridoxal-5'-mono-, di- and triphosphate with certain enzymes of polynucleotide synthesis (DNA-dependent RNA polymerase, DNA-dependent DNA polymerase I and polynucleotide phosphorylase from Escherichia coli and terminal deoxyribonucleotide transferase from calf thymus) was studied. All compounds tested was found to be reversible and competitive inhibitors of these enzymes. The reduction of the enzyme-inhibitor complex with NaBH4 gives rise to the complete irreversible inhibition of the enzymes under study. The comparison of the inhibition constants for pyridoxal and its phosphorylated derivatives with those for mono-, di- and triphosphates of nucleosides was carried out for the enzymes. The results obtained suggest that the modified epsilon-amino-group of lysine residue should be localized at the catalytic site in the vicinity of the pyrophosphate binding area of an enzyme.
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PMID:[Interaction of oligophosphates of pyridoxal with certain enzymes of polynucleotide synthesis]. 38 98

On incubation of cells of E. coli B and MRE 600 (logariphmic phase of growth), treated with toluene in presence of a mixture 14C-nucleoside-5'-diphosphates, Mg2+ or Mn2+ and tris HCl buffer pH 8.0, intracellular synthesis of heteropolyribonucleotide was observed. The synthesis was catalyzed by polynucleotide phosphorylase (PNPase, E. C. 2.7.7.8). An increase in GDP concentration in the medium distinctly decreased the incorporation of other NDP into the polymer (poly-AGUC). If the ratio of ADP, UDP, CDP, GDP in the medium was 1:1:1:0.2, the composition of nitrogenous bases in the heteropolymer produced reflected completely the NDP concentrations in the incubation mixture. Addition of different amino acids (1-lysine, 1-histidine, glycine, 1-phenylalanine) and their mixtures stimulated poly-AGUC synthesis markedly and caused an appreciable alteration in the nucleotide composition of the poly-AGUC synthesized. This phenomenon resembled the effect of amino acids on the activity of partially purified PNPase and on RNA synthesis, catalized by the enzyme in vitro. These data suggest that in bacterial cell, i. e. in vivo, PNPase synthesizes specific RNA polyribonucleotide sequences, participating in protein synthesis or in its regulation.
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PMID:[Nucleotide composition of RNA, synthesized by polynucleotide phosphorylase, in toluene-treated cells of Escherichia coli]. 76 93

1. Basic oligo- and poly-(amino acids) stimulate polyadenylic acid synthesis by purified Clostridium perfringens polynucleotide phosphorylase (nucleoside diphosphate-polyribonucleotide nucleotidyltransferase, EC 2.7.7.8). 2. The effectiveness of the activators increases with chain length up to approx. 20-30 residues. 3. Polymers of the l and dl series are equally effective on a weight-for-weight basis. 4. l-Lysine, d-lysine, diethylamine and triethylamine, as hydrochlorides or hydrobromides, all stimulate the reaction markedly if their concentration is high enough. Their effect is similar to that of sodium chloride. 5. The size of the product depends primarily on the Mg(2+) concentration and basic polymers have a relatively limited effect on it. 6. Polyadenylic acid itself undergoes an Mg(2+)-catalysed non-enzymic hydrolysis.
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PMID:The influence of the size and nature of basic activators on Clostridium perfringens polynucleotide phosphorylase-catalysed polyadenylic acid synthesis. 430 30