FIGURE 5.

polD 3′-5′ exonuclease kinetics. A, reaction scheme, a 50-nt single-stranded 5′-FAM primer was rapidly mixed with a 3-fold excess of polD in the presence of either MnSO₄ or MgSO₄ at 60 °C and quenched with 0.1 n H₂SO₄ using an RQF. B, expected capillary electrophoresis results for processive polD exonuclease hydrolysis in the presence of MnSO₄ or MgSO₄. C, product, <50 nt DNA, was graphed as a function of time and fit to Equation 2 to obtain the rate of polD exonuclease hydrolysis, k_exo, in the presence of MnSO₄ or MgSO₄, ∼110 and 2.5 s⁻¹, respectively.