Table 2.

Single turnover kinetic data for WT and I260Q pol β on single-nucleotide gapped DNA

Sequencea	Protein	k pol (s−1)	K d(dNTP) (μM)	Dk pol b	DKd (dNTP) c	Efficiencyd (μM−1s−1)	Fidelitye	X-foldf
G:dC	WT	12.0±0.9	1.5±0.6			8
	I260Q	3.6±0.08	0.6±0.1			6
G:dA	WT	0.134±0.008	365±59	90	243	3.7 × 10−4	21623
	I260Q	0.095±0.004	16±3	38	27	5.9 × 10−3	1011	21.4
T:dA	WT	12.2±0.6	5.8±0.9			2.1
	I260Q	5.5±0.21	1.9±0.3			2.9
T:dC	WT	0.14±0.01	427±66	87	72	3.3 × 10−4	6364
	I260Q	0.09±0.003	11.5±2.5	61	6	7.8 × 10−3	372	17.1

^aThe primer-template is extG or extT, with templating base G or T; templating base:incoming dNTP is shown.

^bDiscrimination of k_pol= k_pol(correct)/ k_pol(incorrect).

^cDiscrimination of K_d(dNTP) = K_d(dNTP)(incorrect)/ K_d(dNTP)(correct).

^dEfficiency = k_pol/K_d(dNTP).

^eFidelity = (correct efficiency + incorrect efficiency)/incorrect efficiency.

^f X-fold = WT fidelity/I260Q fidelity.