Figure 4.

Comparison of primer extension efficiencies past the lesion by varying the 3′ terminal base pair (N:L). The L-modified or unmodified 34mer template (sequences 1 and 2, respectively, 0.6 µM) was primed with different ³²P-labeled 19mers varied by the nature of the base N at their 3′ end (N = A, sequence 4; N = C, sequence 5; N = G, sequence 7; N = T, sequence 6; 0.05 µM). Reactions were conducted for 30 min at 30°C in the presence of the four dNTPs (100 µM each) using 0.02 U KF exo⁺, 0.01 U KF exo^– and 4 U RT for the unmodified template and using a large enzyme excess for the modified L template (0.2 U KF exo⁺, 0.1 U KF exo^– and 10 U RT).