Figure 6.

Exonuclease site to polymerase site switch in mutants. Primer extension assays were performed by mixing preformed enzyme–DNA (51T/80-mer) complexes with magnesium acetate, physiological concentrations of dNTPs (21) and heparin. Reactions allowing multiple binding events in the absence of heparin are indicated in the figure. The reactions were incubated for 2.5 min at 30°C and resolved on a 10% denaturing acrylamide gel. The band intensities of products were quantified and the percentage of corrected mismatches was calculated by dividing the extension products by the sum of the excision and extension products (Table 3).