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Novikoff hepatoma deoxyribonucleic acid polymerase. Sensitivity of the -polymerase to sulfhydryl blocking agents

1976; Oxford University Press; Volume: 3; Issue: 9 Linguagem: Inglês

10.1093/nar/3.9.2341

1362-4962

Dale W. Mosbaugh, Thomas A. Kunkel, David M. Stalker, James E. Tcheng, Ralph R. Meyer,

DNA and Nucleic Acid Chemistry

Unlike other rβ-class eukaryotic DNA polymerases, the enzyme purified from the Novikoff hepatoma is inhibited by both sulfhydryl blocking agents N-ethylmaleimide (NEM) and p -hydroxymercuribenzoate (pHMB). The degree of sensitivity varies depending on the enzyme purity, pH of the reaction, and the presence of sulfhydryl reducing agents. Novikoff rβ-polymerase activity is unaffected by the presence of 2-mercaptoethanol (2-Me) or dithiothreitol (DTT); however, the combination of 2-mercaptoethanol and NEM or pHMB acts to reverse the inhibition of the sulfhydryl blocking agent. The reversal of inhibition involves more than just a titration of NEM with 2-mercaptoethanol since a) the combination of these two reagents actually stimulates the DNA polymerase, and b) dithiothreitol did not reverse the inhibition. Binding of the polymerase to DNA did not affect the enzyme sensitivity to NEM.