Fig. 4-. Ionic strength influences Ape1 endonuclease activity.

A) Graph depicting AP site incision activity of Ape1^WT on the specified substrate in a solution containing 5 mM KCl. See also supplementary Fig. S6A for the gels.

B) Graph depicting AP site incision activity of Ape1^N∆33 on the specified substrate in a solution containing 5 mM KCl. See also supplementary Fig. S7A for the gels. Graphs describe the percentage of conversion of substrate (S) into product (P) as a function of the dose of protein on the specified substrate. Average values are plotted with standard deviations of three loadings of the same experiment as a function of protein dosage. Standard deviation values were always less than 10% of the mean of experimental points.

C) AP site incision activity on S8 ODN decreases in raising ionic strength. Graph depicting endonuclease activity experiments performed with Ape1^WT or Ape1^N∆33 as described in Materials and methods section. Average values are plotted with standard deviations of three loadings of the same experiment as a function of KCl concentration used. Standard deviation values were always less than 10% of the mean of experimental points. See also supplementary Fig. S7C for the gels.

D) Histograms summarizing the different endonuclease activities of Ape1^WT (left) and Ape1^N∆33 (right) on the specified substrates at the indicated fmol of the enzyme in the stated KCl concentrations on the different substrates. Each bar was compared with the activity of the protein on ds-F in the corresponding saline condition.