TABLE 1.

Nucleotide insertion opposite Gua and N²-ethyl-Gua by DNA pol ι K_m and k_cat values were determined by quantifying gel band intensities using ImageQuant, and non-linear regression analysis of product versus [dNTP] curves, using SigmaPlot 8.0.2.

Metal ion	dNTP	Km	kcat	kcat/Km	Relative insertion frequencya
		μm	min–1	min–1 μm–1
At template N2-ethyl-Gua
0.075 mm Mn2+
	Cyt	0.10 ± 0.012	425 ± 15	4.3 × 103	1
	Thy	0.030 ± 0.014	225 ± 25	7.5 × 103	1/0.6
2 mm Mg2+
	Cyt	36 ± 3	74 ± 12	2.1 × 100	1
	Thy	650 ± 180	115 ± 18	1.8 × 10–1	1/12
At template Gua
0.075 mm Mn2+
	Cyt	0.15 ± 0.020	700 ± 40	4.7 × 103	1
	Thy	0.085 ± 0.020	200 ± 15	2.4 × 103	1/2
2 mm Mg2+
	Cyt	49 ± 4	112 ± 18	2.3 × 100	1
	Thy	220 ± 60	50 ± 6	2.3 × 10–1	1/10

^aRelative insertion frequency is calculated as 1/([k_cat/K_m, correct]/[k_cat/K_m, incorrect])