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

Distribution of the DNA polymerase I large fragment (Klenow fragment) was studied during fractionation of the E. coli MRE-600 cell-free extract with polyethylenimine. On the basis of the results obtained a simple procedure is proposed that enables the Klenow fragment to be obtained as a coproduct of DNA polymerase I, RNA polymerase, polynucleotide phosphorylase, nucleotide kinases with acetokinase and nucleoside deoxy-ribosyltransferase in the framework of a combined technological scheme.
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PMID:[Behavior of the large fragment of DNA polymerase I (the Klenow fragment) during fractionation of a cell-free extract of E. coli MRE-600]. 330 31

Spin-labeled copolymers of 4-thiouridine and uridine (ls4U,U)n] that contain various amounts of spin label (l) were synthesized by either (i) chemical alkylation of the 4-thiouridine-uridine copolymers (s4U,U)n prepared by copolymerizing 4-thiouridine 5'-diphosphate (s4UDP) and UDP or (ii) copolymerization of spin-labeled s4UDP with UDP using polynucleotide phosphorylase. The effect of (s4U,U)n and (ls4U,U)n on avian myeloblastosis virus (AMV) RNA-dependent DNA polymerase (RNA-dependent DNA nucleotidyltransferase, EC 2.7.7.7; reverse transcriptase) was studied to determine whether the presence of potentially reactive thiol groups or spin labels enhances the inhibitory properties of the copolymers as compared to (U)n. Inhibition by (s4U,U)n gradually increases as the percentage of thiolation increases. Enhanced inhibition by (s4U,U)n appears to be due to the interaction of the thiol groups of (s4U,U)n with the thiol group(s) of the polymerase, because inhibition by (s4U,U)n (8% thiolated) in the presence of dithiotreitol resembles that by (U)n. In contrast, inhibition by (ls4U,U)n containing 3% spin label resembles that by (U)n; however, increasing the spin label to 6% or 12% results in enhanced inhibition by (ls4U,U)n as compared to that by (U)n, and dithiothreitol has no effect on enhanced inhibition by (ls4U,U)n. These results suggest that the mechanism of inhibition observed with (ls4U,U)n with a ls4U:U ratio > 1:33 differs from the mechanism for (s4U,U)n and involves complex formation between the spin label and the essential Zn2+ of RNA-dependent DNA polymerase.
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PMID:Reactivity of reverse transcriptase toward (s4U,U)n copolymers and spin-labeled nucleic acid lattices. 615 32

In an effort to search for good methods for the enzymatic synthesis of polynucleotide analogs with antitemplate activity, 5-methylthiouridine-5'-diphosphate (ms5UDP) has been synthesized and investigated as a substrate for polynucleotide phosphorylase. While ms5UDP was polymerized at a very low rate to give a 6% yield of polynucleotides by the polynucleotide phosphorylase of Micrococcus luteus, it was utilized more efficiently by the corresponding enzyme of Escherichia coli resulting in a 15% yield of poly (5-methylthiouridylic) acid. Results of the co-polymerization of ms5UDP and UDP revealed that the ratio of 5-methylthiouridylate to uridylate residues in the polynucleotide product was lower than the ratio of ms5UDP to UDP in the substrate mixture. The 5-methylthio group conferred only minute changes on the conformation of the modified polyuridylic acid, and the complexes formed between poly-(5-methylthiouridylic) acid and poly(adenylic) acid possessed slightly higher Tm values than did the unmodified counterparts. Poly(5-methylthiouridylic) acid was a potent inhibitor of calf thymus DNA polymerase alpha.
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PMID:Synthesis and properties of poly 5-methylthiouridylic acid. 654 63

In the presence of Mg2+ ions, polynucleotide phosphorylase (PNPase, EC 2.7.7.8) is known to synthesize RNA-like polymers using ribonucleoside-5'-diphosphate (NDP) substrates but to be unable to utilize deoxyribonucleoside substrates. Our experiments show that when MgCl2 is replaced by FeCl3, PNPase becomes able to synthesize deoxyheteropolymers using deoxyribonucleoside-5'-diphosphates (dNDPs). The deoxyheteropolymer formed from the four dNDPs is degraded by pancreatic DNase, but not by RNase, and is readily used as a template by DNA-dependent DNA polymerase. Synthesis of this DNA-like polymer is accomplished de novo without the help of any primer or preexisting template. What is more, dA/dG and dC/dT ratios of polymers synthesized by different bacterial PNPases closely match ratios found in DNA of the bacterial species the enzyme came from.
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PMID:De Novo Synthesis of DNA-Like Molecules by Polynucleotide Phosphorylase In Vitro 866 1