ON MECHANISM OF INHIBITION BY FLUORIDE IONS OF DNA POLYMERASE REACTION

1. 1. In the presence of Mg2+, the DNA polymerase reaction was inhibited about 90 percent by 0.16 M F-. However, in the presence of Mn2+ instead of Mg2+, F- had no inhibitory effect even at a concentration of 0.33 M. 2. 2. A precipitable radioactive complex was formed when Mg2+, the substrates dATP, dGTP, dCTP and [3H]dTTP and F- were incubated with or without DNA polymerase. No precipitable complex was formed when Mn2+ was used instead of Mg2+. Thus, F- inhibition of DNA polymerase activity is probably due to formation of insoluble complexes containing Mg2+, deoxynucleosidetriphosphates and F-. 3. 3. The formation of precipitable F- complexes was dependent on the presence of Mg2+ and a phosphate compound. Nucleoside triphosphates, inorganic tripolyphosphate and pyrophosphate formed complexes with Mg2+ and F- to a larger extent than did nucleoside monophosphates and orthophosphate. Nucleoside diphosphates seem to have an intermediary position in this respect. 4. 4. The velocity of formation of precipitable complexes increased with increasing Mg2+ and F- concentrations and decreased at low pH or at low temperatures. © 1969.