Table 3.

Observed rates for formation of fluorescent complexes between wild-type and mutant T4 DNA polymerases and 2AP-DNA substrates

Enzyme	Fluorescent complex formation rate, s−1
	G+C-rich DNA substrate			A+T-rich DNA substrate
	dsDNA		ssDNA	dsDNA		ssDNA
Wild type	71.0  ±  1.4		406.0  ±  5.5	204.7  ±  4.8		530.3  ±  18.9
D131N	61.1  ±  1.2		263.0  ±  13.6	114.7  ±  1.9		322.5  ±  8.6
G255S*	69.7  ±  2.8  (0.3)	18.6  ±  1.3  (0.7)	263.5  ±  6.6	123.8  ±  21.4  (0.3)	32.9  ±  2.9  (0.7)	384.9  ±  13.8

Fluorescent complex formation was measured in the absence of Mg²⁺ as described in the text. The DNA substrates are also described in the text. The single-stranded DNA (ssDNA) is the 2AP-labeled primer strand of the double-stranded DNA (dsDNA) substrates. The reactions for the G+C-rich dsDNA are shown in Fig. 2. The observed rates are independent of enzyme concentration under the conditions used (19). The rates correspond to bimolecular association rates that range from about 0.5 to 5 × 10⁸ M⁻¹⋅s⁻¹. 

^*Two rates were detected for the formation of a fluorescent complex between the G255S-DNA polymerase and the dsDNA substrates. The relative amplitudes of the two phases are indicated in parentheses.