FIGURE 6.

Pre-steady-state kinetics of incorporation of dCTP opposite N²-AnthG by Dpo4 in the absence and presence of excess unlabeled DNA trap. Dpo4 (70 nm) was incubated with 24-mer/36-mer primer·template complex containing N²-AnthG (120 nm) in a rapid quench-flow instrument and mixed with a mixture of either (i) 5 mm MgCl₂/1 mm dCTP or (ii) 5 mm MgCl₂/1 mm dCTP/1200 nm unlabeled trap 24-mer/36-mer DNA to initiate reactions. All polymerization reactions were quenched with 0.6 m EDTA at the indicated time intervals. The data were fit to the burst equation, y = A(1 – exp(–k_pt)) + k_sst (Equation 1). The burst rates were estimated to be 0.46 (± 0.04) s^–1 for the case with dCTP only and 1.7 (± 0.2) s^–1 for the case with the DNA trap.