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. 2000 Oct 24;97(23):12469–12474. doi: 10.1073/pnas.230448397

Figure 2.

Figure 2

Effect of deletion of residues 401–404 on the polymerase and exonuclease activity of T7 DNA polymerase. (A) The DNA polymerase activity of wild-type T7 DNA polymerase (○) or T7 polΔ401–404 (●) was assayed by using a circular M13 ssDNA template annealed to a 25-nt DNA primer. The rate of incorporation of [3H]dTMP was plotted against different enzyme concentrations. (B) The 3′-to-5′ dsDNA exonuclease activity of wild-type (○) or T7 polΔ401–404 (●) was assayed by using a circular M13 ssDNA template annealed to a radiolabeled oligonucleotide as described in Materials and Methods. The rate of degradation of the primer was measured with time. One hundred percent primer–template corresponds to 25 fmol M13 DNA.