Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In HEp-2 and amnion cell cultures infected with type 1 adenovirus the DNase activity of cell extracts was measured on 32P-labelled Escherichia coli DNA substrate. Enzyme activity was demonstrated by the acid soluble nucleotides released from the 32P-DNA and by the decreased sedimentation rate of labelled DNA. High DNase activity was measured in both adenovirus infected and in untreated HEp-2 cell extracts. Nuclease activity of the amnion host cells being much lower than that of HEp-2 cells, virus-associated endonuclease activity was successfully demonstrated in them. Purified type 1 adenovirus decreased the sedimentation rate of 32P-labelled E. coli DNA. The phenomenon is explained by the virion-associated endonuclease activity. Trypsin inactivated and anti HEp-2 IgG failed to inhibit the virion nuclease. An association between endonuclease and trypsin sensitive penton is assumed.
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PMID:Demonstration of adenovirus associated endonuclease. 77 3

A quantitative study has been made on the action of rat nuclear Ca-Mg endonuclease on rat liver nuclei. In a standard 30 minute digest 0.5-1.5% of the DNA was rendered acid soluble, 1.5-4% of the chromatin was rendered buffer soluble, 50-60% of the potential cleavage sites were actually cleaved, and these cleavages were distributed evenly throughout the bulk of the genome. During these standard digests there was no significant loss of histones either in aggregate or relative to each other. Trypsin digestion of the nuclei to a trypsin resistant core did not lower the specificity of the Ca-Mg endonuclease cleavages or expose other sites to its action. Evidence is presented that indicates Ca-Mg endonuclease and micrococcal nuclease attack the same sites rather than different sites with the same spacing.
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PMID:The reaction of the Ca-Mg endonuclease with the A-sites of rat nucleoprotein. 117 28

The cell-associated glycoproteins of respiratory syncytial (RS) virus included GP1 (90K), VP70 (70K), VGP48 (48K) and GP26 (26K). Although present in infected cells, there was no VP70 in purified virus. Trypsin treatment of infected cells removed 80 to 90% of VP70 as well as its products VGP48 and GP26. This suggested that most of the VP70 in the cell is located on the plasma membrane. The glycoproteins of purified RS virus (GP1, VGP48 and GP26) contain mannose, galactose and fucose as well as glucosamine, but the quantity of mannose in GP1 is low when compared to that of the other three sugars. The effects that follow the treatment of infected cells with the glycosylation inhibitors tunicamycin and monensin, and the treatment of the immunoprecipitated product of pulse-chase experiments with endonuclease H demonstrated that VP70 and its products contained N-linked oligosaccharides, and that the oligosaccharides of the mature VGP48 subunit were of the complex type, while GP1 contained both N- and O-linked oligosaccharides. The non-glycosylated forms of VP70 and GP1 have estimated mol. wt. of 50K and 33K respectively. Therefore, the carbohydrate contribution to the mol. wt. of VP70 and GP1, as determined by PAGE, was equivalent to 20K for the former and 57K for the latter. The majority of the GP1 oligosaccharides were O-linked, a form of sugar linkage not previously found among paramyxoviruses.
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PMID:Respiratory syncytial virus polypeptides. IV. The oligosaccharides of the glycoproteins. 391 49

DNA endonucleases in rat liver nuclei extracts were examined by SDS-polyacrylamide gel electrophoresis followed by zymogram analysis. Four polypeptides of 120, 54, 31 and 28 kDa, which have DNA endonuclease activity, were shown to occur in the extract isolated in the presence of phenylmethanesulfonyl fluoride (PMSF), a proteinase inhibitor. Isolation without PMSF, as well as storage at -20 degrees C, or autodigestion, resulted in multiplication of active polypeptides in the extracts. Trypsin digestion led to the appearance of an active > 140 kDa polypeptide, indicating the existence of a potential endonuclease precursor in the nuclear extract.
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PMID:In vitro proteolysis of endonucleases in rat liver nuclei extracts. 766 99

Gel shift analysis reveals [Lagunavicius, A., & Siksnys, V. (1997) Biochemistry 36 (preceding paper in this issue)] that at pH 8.3 in the absence of Mg2+, MunI restriction endonuclease exhibits little DNA binding specificity, as compared with the D83A and E98A mutants of MunI. This suggests that charged carboxylate residue(s) influence the DNA binding specificity of MunI. In our efforts to establish the determinants of MunI binding specificity, we investigated the possible role of the ionic milieu, and we found that lowering pH or elevating Ca2+ levels per se induces specific DNA recognition by WT MunI. In contrast to the binding experiments at pH 8.3, gel shift analysis at pH 6.5 indicated tight sequence-specific binding of WT MunI in the absence of Mg2+, suggesting that protonation of active site carboxylate residue(s) which manifest anomalously high pKa value(s) control binding specificity. Interestingly, Ca2+ ion concentrations, which did not support DNA cleavage by MunI also induced DNA binding specificity in WT MunI at pH 8.3. To explore possible structural changes upon DNA binding, we then used a limited proteolysis technique. Trypsin cleavage of MunI-DNA complexes indicated that in the presence of cognate DNA the MunI restriction endonuclease became resistant to proteolytic cleavage, suggesting that binding of specific DNA induced a structural change. CD measurements confirmed this observation, suggesting minor secondary structural differences between complexes of MunI with cognate and noncognate DNA. These results therefore suggest that binding of MunI to its recognition sequence triggers a conformational transition that correctly juxtaposes active site carboxylate residues, which then chelate Mg2+ ions. In the absence of Mg2+ ions, at pH 8.3, conditions in which carboxylate groups would be expected to be completely ionized, electrostatic repulsion between charged carboxylates and phosphate oxygens is enhanced such as to interfere with specific DNA binding. Elimination of such repulsive constraints by replacement of carboxylate residues, by lowering pH, or by metal ion binding, then promotes MunI binding specificity.
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PMID:DNA binding specificity of MunI restriction endonuclease is controlled by pH and calcium ions: involvement of active site carboxylate residues. 928 52