TABLE 5.

Dissociation rates and lifetimes of protein·DNA complexes

Respective dissociation rate constants (k_off) were measured by stopped-flow FRET; lifetimes were determined according to (1/k_off).

Protein complex	koff (s−1) 37 °C, lifetime	koff (s−1) 25 °C, lifetime	koff (s−1) 15 °C, lifetime	koff (s−1) 6 °C, lifetime
	ms	ms	ms	ms
WT	0.083 ± 0.001	0.046 ± 0.001	0.033 ± 0.001	0.032 ± 0.001
	12.4 × 103	21.7 × 103	30.3 × 103	31.2 × 103
W70A	NDa	0.5 ± 0.013	0.26 ± 0.003	0.2 ± 0.001
	>0.7 × 103	2.0 × 103	3.84 × 103	5.0 × 103
W70L	ND	ND	0.2 ± 0.003	0.14 ± 0.002
	>0.7 × 103	>0.7 × 103	5.0 × 103	7.14 × 103
W70F	0.1 ± 0.001	0.08 ± 0.005	0.065 ± 0.003	0.06 ± 0.003
	10 × 103	12.5 × 103	15.4 × 103	16.6 × 103
W70Y	0.1 ± 0.002	0.09 ± 0.009	0.07 ± 0.005	0.07 ± 0.004
	10 × 103	11.1 × 103	14.3 × 103	14.3 × 103

^a ND means not determined due to rapid dissociation (lifetime <7 × 10² ms).