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)

1. Conditions have been established for the estimation of molecular weights of proteins by analytical gel filtration and sucrose-density-gradient centrifugation in 2.5m-potassium chloride-1m-sodium chloride; Halobacterium cutirubrum polynucleotide phosphorylase, DNA-dependent RNA polymerase and RNA-dependent RNA polymerase have been studied by these methods. 2. The RNA-dependent polymerase has also been studied by density-gradient centrifugation in the absence of salt. 3. All three proteins are of unusually low molecular weight compared with similar enzymes from non-halophilic bacteria.
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PMID:Nucleic acid enzymology of extremely halophilic bacteria. Gel-filtration and density-gradient-centrifugation studies of the molecular weights of Halobacterium cutirubrum polynucleotide phosphorylase and deoxyribonucleic acid- and ribonucleic acid-dependent ribonucleic acid polymerases. 511 75

The hypothesis that vestiges of the ancestral RNA-dependent RNA polymerase involved in the replication of RNA genomes of Archean cells are present in the eubacterial RNA polymerase beta' subunit and its homologues is discussed. We show that in the DNA-dependent RNA polymerases from the three cellular lineages a very conserved sequence of eight amino acids also found in a small RNA-binding site previously described for the E. coli polynucleotide phosphorylase and the S1 ribosomal protein is present. The optimal conditions for the replicase activity of the avian myeloblastosis virus reverse transcriptase are presented. The evolutionary significance of the in vitro modifications of substrate and template specificities of RNA polymerases and reverse transcriptases is also discussed.
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PMID:The origin and early evolution of nucleic acid polymerases. 1153 40

Polynucleotide phosphorylase (polyribonucleotide:orthophosphate nucleotidyltransferase, EC 2.7.7.8) activity has been found in many prokaryotes and studied in detail since 1955. Such enzymes have been detected also in plants. We now describe the purification of polynucleotide phosphorylase from cucumber cotyledons and leaves. This enzyme is a complex of three subunits, possibly not identical, of about M(r) 50,000. Its enzymatic properties are similar to those of the tobacco enzyme. Unlike the prokaryotic enzymes, the plant enzyme shows activity in the absence of primer but is to various extents stimulated by various ribopolynucleotides or RNAs. RNA-dependent RNA polymerase, not previously shown to exist in non-virus-infected cucumber, has been found to be present at a low level and was separated from the much greater amount of polynucleotide phosphorylase, although some of the physical properties of the two enzymes are rather similar.
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PMID:Purification and characterization of polynucleotide phosphorylase from cucumber. 1659 47