Table 2.

Extension from Gua:Cyt, Gua:Thy and N²-ethyl-Gua:Cyt, N²-ethyl-Gua:Thy base pairs by DNA pol κ^a

Metal ion	Base pair	Km (μM)	kcat (min−1)	kcat/Km (min−1 μM−1)	relative extension frequencyb
At Template N2 -ethyl-Gua
0.075mM Mn2+
	N2etGua:Cyt	1500 ± 1200	430 ± 250	2.8 × 10−1	1
	N2etGua:Thy	100 ± 20	20 ± 1	2.0 × 10−1	1/1.4
2mM Mg2+
	N2etGua:Cyt	90 ± 60	390 ± 110	4.3	1
	N2etGua:Thy	12 ± 2	40 ± 0.7	3.3	1/1.3
At Template Gua
0.075mM Mn2+
	Gua:Cyt	630 ± 300	200 ± 60	3.2 × 10−1	1
	Gua:Thy	70 ± 20	30 ± 2	4.3 × 10−1	1/0.7
2mM Mg2+
	Gua:Cyt	50 ± 30	530 ± 130	11	1
	Gua:Thy	6.9 ± 1.3	60 ± 2	8.7	1/1.2

^aK_m and k_cat values were determined by quantifying gel band intensities using ImageQuant software and non-linear regression analysis of product vs [dNTP] curves using SigmaPlot 8.0.2.

^bRelative extension frequency was calculated as 1/([k_cat/K_m]_correct/[k_cat/K_m]_incorrect).