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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)

We report here the presence of two enzymatic activities associated with highly purified preparations of polynucleotide phosphorylase from Micrococcus luteus. The first, a nuclease activity, which is not separated from the phosphorylase on hydroxylapatite, may be due to substitution of H2O for phosphate in the phosphorolysis reaction. The second activity, a deoxyadenylate kinase, the bulk of which is not resolved from the phosphorylase using gel filtration, sucrose density gradient centrifugation, DEAE-Sephadex, or hydroxylapatite chromatography, may represent a new activity of polynucleotide phosphorylase or be due to an enzyme which is tightly bound to the phosphorylase. Several properties of the kinase are described and its possible significance with respect to the overall enzyme mechanism is discussed.
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PMID:A deoxyadenylate kinase activity associated with polynucleotide phosphorylase from Micrococcus luteus. 18 14

Two hexanucleotides A-U-G-U-G-A and C-A-A-U-U-G were synthesized from the chemically synthesized trimers C-A-A and A-U-G by addition of 2'-O-(o-nitrobenzyl)nucleoside diphosphates using polynucleotide phosphorylase isolated from either Escherichia coli or Micrococcus luteus. In each reaction the preference of the enzyme was tested. The o-nitrobenzyl group was removed after addition of the mononucleotide and the deblocked product was isolated by chromatography on DEAE-Sephadex in high yields.
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PMID:A method for the synthesis of oligonucleotide by single addition of 2'-O-(o-nitrobenzyl)nucleoside 5'-diphosphates using polynucleotide phosphorylase. 38 86

Purified preparations of pigeon liver PNPase (E.C. 2.4.2.1) have been obtained by acid preparation of liver homogenates at pH = 5,followed by a fractionation with ammonium sulphate (25-50% saturation) and by a chromatographic adsorption on DEAE-cellulose. The preparation obtained shows a PNPase specific activity 325 times greater than that of the original homogenates. Kinetic studies carried out with homogenates and purified preparations of pigeon liver PNPase seem to suggest that inosine and deoxynosine react on the same catalytic site of the enzyme molecule.
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PMID:[Purification of purine nucleoside phosphorylase activity on deoxyinosine (author's transl)]. 82 97

1. Polynucleotide phosphorylase from a chlortetracycline-producing strain of Streptomyces aureofaciens was isolated by Polymin P fractionation. Using chromatography on DEAE-cellulose and Sephadex G-150 the enzyme, which appears homogeneous in gel chromatography and sedimentation analysis, was purified 2000-fole giving a final yield of 15%. 2. The sedimentation coefficient (s-o 20, w) of the native enzyme in 0.2 M NaCl is 9.15 S and its molecular weight is 210 000 plus or minus 15 000. Molecular weight estimated by sodium dodecylsulfate gel electrophoresis was about 100 000. 3. We have determined the optimal conditions for nucleoside 5'-diphosphate polymerization, their phosphate exchange and phosphorolysis of polyribonucleotides catalysed by polynucleotide phosphorylase from S. aureofaciens. 4. Chlortetracycline is a competitive inhibitor of S. aureofaciens polynucleotide phosphorylase. 5. Polynucleotide phosphorylase is activated in the polymerization reaction by ionic strength (K+, Na+, NH4+) while polyribonucleotide phosphorolysis is activated only by NH4+.
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PMID:Polynucleotide phosphorylase from Streptomyces aureofaciens: purification and properties. 112 94

Using ion-filtration chromatography on DEAE-Sephadex A-25, a homogeneous polynucleotide phosphorylase having specific activity of 350--360 u./mg and containing no admixtures of nucleases or phosphatases was obtained. Injection of 32P phosphate to hypophysectomized animals was accompanied by the label incorporation into the enzyme molecule. The data obtained indirectly indicate that the enzyme is activated by phosphorylation and is inactivated by dephosphorylation, both processes being mediated by some factor found in liver cytosol of intact animals.
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PMID:[Polynucleotide phosphorylase from rat liver: isolation and regulation of its activity by growth hormone]. 709 86

The polynucleotide phosphorylase of Thermus aquaticus was purified using ammonium sulfate fractionation and column chromatography on DEAE-cellulose, heparin-Sepharose 4B and DEAE-Sephadex A25. The enzyme was purified 1500-fold and was 90-95% homogeneous as checked by polyacrylamide gel electrophoresis. It has a molecular weight of 275 000 and consists of four identical subunits. The Km values for the enzyme as determined in polymerization (ADP, GDP, UDP) and phosphorolytic reactions (poly A, poly U) are in the same concentration range as in the case of the enzyme deriving from mesophilic microorganisms. Furthermore, the enzyme is primer dependent and its activity is lost gradually at temperatures higher than 65 degrees C. In the base ratio of the copolymers followed the input base ratio polymerization reactions with polyUA, while with polyAG and polyUG a marked difference between the initial base ratio and the base composition of copolymers was observed.
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PMID:The purification of polynucleotide phosphorylase from Thermus aquaticus by the use of heparin-sepharose 4B affinity chromatography. 734 86