Table 2.

Effect of non-hydrogen-bonding base analogues on reactions catalyzed by Dbh polymerase

Reaction	Rate (s-1)	kpol/Kd (M-1s-1)
Analogues at insertion sitea:
Template-T + dATP		1.2 × 103
Template-F + dATP		0.72
Template-F + dZTP		0.46
Template-F + dQTP		0.62
Analogues at primer terminusb:
(primer)T-A(template) + dGTP	0.10
(primer)F-Z(template) + dGTP	1.3 × 10-4
(primer)F-Q(template) + dGTP	2.9 × 10-4
(primer)A-T(template) + dGTP	1.4 × 10-2
(primer)Z-F(template) + dGTP	2.9 × 10-5
(primer)Q-F(template) + dGTP	2.3 × 10-4

^aBecause of the high K_d(dNTP) of Dbh, it was not possible to use a high enough dNTP concentration to saturate the reaction, and therefore individual k_pol and K_d values could not be obtained. Even with T-dATP, the reaction rate did not plateau at concentrations up to 4 mM dATP, and we estimate a K_d in excess of 1.5 mM. The efficiency (k_pol/K_d) was determined from the slope of the plot of rate vs. dNTP concentration, at low dNTP concentrations.

^bRates were compared at 2 mM dGTP. In every case, the rate at 2 mM dGTP was 54 to 77% of that at 10 mM, suggesting no substantial variation in dGTP affinity in these reactions.