Table 1. Steady-state kinetic efficiencies for single-nucleotide insertions by DNA Pol I (Klenow fragment, exonuclease-deficient) with variably sized template bases.

dNTP	Template base	Vmax, %·min–1	KM, μM	Efficiency, Vmax/KM	Relative efficiency
dATP	H	0.90 ± 0.18	20 ± 2	4.5 × 104	3.5 × 10–3
	F	24 ± 3	9.4 ± 2.9	2.6 × 105	2.0 × 10–1
	L	27 ± 5	3.3 ± 2.8	8.2 × 106	6.5 × 10–1
	B	12 ± 1	21 ± 5	5.7 × 105	4.4 × 10–2
	I	1.3 ± 0.2	26 ± 11	5.0 × 104	3.8 × 10–3
	T	24 ± 1	1.9 ± 0.5	1.3 × 107	1
dGTP	H	0.025 ± 0.007	600 ± 210	4.2 × 101	3.2 × 10–6
	F	0.0071 ± 0.0006	36 ± 12	2.0 × 102	1.5 × 10–5
	L	0.029 ± 0.007	190 ± 90	1.5 × 102	1.2 × 10–5
	B	0.023 ± 0.005	220 ± 100	1.0 × 102	7.7 × 10–6
	I	0.017 ± 0.001	58 ± 18	2.9 × 102	2.2 × 10–5
	T	0.41 ± 0.15	56 ± 34	7.3 × 103	5.6 × 10–4
dCTP	H	0.031 ± 0.006	100 ± 60	3.1 × 102	2.4 × 10–5
	F	0.071 ± 0.011	33 ± 11	2.2 × 103	1.7 × 10–4
	L	0.021 ± 0.003	25 ± 13	8.4 × 102	6.5 × 10–5
	B	0.038 ± 0.005	79 ± 33	4.8 × 102	3.7 × 10–5
	I	0.036 ± 0.001	20 ± 8	1.8 × 103	1.4 × 10–4
	T	0.022 ± 0.006	46 ± 28	4.8 × 102	3.7 × 10–5
dTTP	H	0.062 ± 0.022	61 ± 37	1.0 × 103	7.7 × 10–5
	F	0.12 ± 0.03	22 ± 13	5.5 × 103	4.2 × 10–4
	L	0.13 ± 0.04	18 ± 18	7.2 × 103	5.5 × 10–4
	B	0.20 ± 0.03	37 ± 12	5.4 × 103	4.2 × 10–4
	I	0.085 ± 0.037	48 ± 39	1.8 × 103	1.4 × 10–4
	T	0.012 ± 0.004	38 ± 38	3.2 × 102	2.5 × 10–5

The template contained variably sized thymidine analogs. The kinetics were measured in a buffer containing 5 mM template–primer DNA, 0.005 or 0.1 unit/ml enzyme, 50 mM Tris-HCl buffer (pH 7.5), 10 mM MgCl₂, 1 mM dithiothreitol, and 50 mg/ml bovine serum albumin at 37°C. V_max was normalized to the lowest enzyme concentration used. Relative efficiency is relative to insertion of dATP opposite T.