Comparisons of the relative reactivity of polymerases with DNA and dNTP. The pol and O2-alkyl-dT DNA pairing in each panel is as follows: (A) pol η and O2-Me-dT; (B) pol η and O2-POB-dT; (C) pol ι and O2-Me-dT; (D) pol ι and O2-POB-dT; (E) pol ι and O2-Me-dT; (F) pol ι and O2-POB-dT. Each panel shows the insertion of 25 μM dATP opposite dT (black circle). The polymerase (250 nM) and DNA (25 nM) were reacted with 50 μM dATP (black square), dCTP (open diamond), dGTP (black diamond), dTTP (open square); dT, O2-Me-dT, or O2-POB-dT. The solid lines are the best fit to the burst equation with the purine dNTP represented by the solid line and the pyrimidine dNTP represented by the dashed line.