FIGURE 8.

dGTPase activity of the DNA binding-deficient Dgt mutant (S34D/G37E). A, dGTPase activity of mutant and wild-type Dgt enzyme in the absence of DNA. The V_max and K_m of the mutant enzyme were 3.85 ± 0.65 s⁻¹ and 16 ± 4 μm, respectively, compared with 4.2 ± 0.2 s⁻¹ and 33 ± 1.5 μm for the wild-type enzyme. Conditions were as described in the legend to Fig. 6. B, dGTPase activity of the S34D/G37E enzyme with or without DNA. The DNA concentration (ss 40-mer) was 50 nm, and the enzyme concentration 4 nm. Results are average of three repeated experiments.