FIGURE 1.

Intrinsic processivity of bacteriophage T4 wild type and mutant DNA polymerases. Primer elongation was determined in the presence of a heparin trap as described (see Materials and Methods). Reaction products were separated under denaturing gel electrophoresis conditions. (A) Almost no primer extension was detected if heparin was added before the DNA polymerase in the control reaction, lane 4. Significant primer extension was observed in reactions with 80 μM dNTPs: wild type T4 DNA polymerase, lane 1; L412M-DNA polymerase, lane 2; I417V-DNA polymerase, lane 3. Less primer extension was observed when dNTPs were reduced to 1 μM: wild type T4 DNA polymerase, lane 5; L412M-DNA polymerase, lane 6; I417V-DNA polymerase, lane 7. Prominent termination sites are indicated. (B) Short film exposure of the reactions in panel A. The figure is modified from Reha-Krantz and Nonay (1994) and is shown with permission from the ASBMB.