{"title":"Inhibition of Escherichia coli DNA polymerase I by association of the template with an N-methylisatin-β-thiosemicarbazone·copper complex","authors":"Peter Mikelens, Bruce Woodson, Warren Levinson","doi":"10.1016/S0006-3061(00)80131-3","DOIUrl":null,"url":null,"abstract":"<div><p>The deoxyribonucleic acid polymerase I (deoxynucleoside triphosphate: DNA deoxynucleotidyl transferase; E.C 2.7.7.7) of <em>Escherichia coli</em> is inhibited more than 99% by 50 μM <em>N</em>-methylisatin-β-thiosemicarbazone (M-IBT) + 50 μM CuSO<sub>4</sub>. When added alone, 50 μM M-IBT enhanced activity, whereas 50 μM CuSO<sub>4</sub> alone inhibits the reaction by 40%. Inhibition is reversed by the competing chelating agent ethylenediamine tetraacetate. A related compound, 1-formylisoquinoline thiosemicarbazone, also inhibits enzyme activity in the presence of cupric ions.</p><p>Polymerase inhibition by M-IBT + CuSO<sub>4</sub> is relieved when increasing amounts of nucleic acid, but not increasing amounts of enzyme, are added. This suggests that the DNA template, not the polymerase, is the target of inhibition by M-IBT + CuSO<sub>4</sub>.</p><p>The biological pertinence of nucleic acid as a target for the M-IBT + CuSO<sub>4</sub> complex is shown by the binding of Rous sarcoma virus (RSV) 70 S RNA to the complex formed within the intact virus particle. The importance of metal ions for this drug action is supported by the ability of ethylenediamine tetraacetate to reverse the binding.</p></div>","PeriodicalId":9177,"journal":{"name":"Bioinorganic chemistry","volume":"9 6","pages":"Pages 469-478"},"PeriodicalIF":0.0000,"publicationDate":"1978-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0006-3061(00)80131-3","citationCount":"4","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bioinorganic chemistry","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0006306100801313","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 4
Abstract
The deoxyribonucleic acid polymerase I (deoxynucleoside triphosphate: DNA deoxynucleotidyl transferase; E.C 2.7.7.7) of Escherichia coli is inhibited more than 99% by 50 μM N-methylisatin-β-thiosemicarbazone (M-IBT) + 50 μM CuSO4. When added alone, 50 μM M-IBT enhanced activity, whereas 50 μM CuSO4 alone inhibits the reaction by 40%. Inhibition is reversed by the competing chelating agent ethylenediamine tetraacetate. A related compound, 1-formylisoquinoline thiosemicarbazone, also inhibits enzyme activity in the presence of cupric ions.
Polymerase inhibition by M-IBT + CuSO4 is relieved when increasing amounts of nucleic acid, but not increasing amounts of enzyme, are added. This suggests that the DNA template, not the polymerase, is the target of inhibition by M-IBT + CuSO4.
The biological pertinence of nucleic acid as a target for the M-IBT + CuSO4 complex is shown by the binding of Rous sarcoma virus (RSV) 70 S RNA to the complex formed within the intact virus particle. The importance of metal ions for this drug action is supported by the ability of ethylenediamine tetraacetate to reverse the binding.