Figure 5.

Measurement of the DNA dissociation rate for the E′•DNA•dNTP complex at 56°C. A preincubated solution of Dpo4 (2.4 nM) and 5′-[³²P]-labeled-D-1 (250 nM) was mixed with ddTTP (1.2 mM) in the absence (filled circles) or presence (open circles) of the next correct nucleotide dCTP (1.2 mM). The data were fit to Equation (4) (Materials and Methods section) to give a steady-state rate in the absence and presence of dCTP of 0.063 ± 0.001 s⁻¹ and 0.0028 ± 0.0004 s⁻¹, respectively.