Figure 4.

The clamp/polymerase activity of different RTs and DNA polymerases. All enzymes (with equal DDDP activities, tested by a DNA–primer extension assay, see Supplementary Figure S1) were incubated with the indicated substrate as described in ‘Materials and Methods’ section. MLV RT was assayed with 5 mM MgCl₂ or 0.8 mM MnCl₂ while Tf1 RT with 5 mM MgCl₂ or 0.5 mM MnCl₂. All other enzymes were assayed with 5 mM MgCl₂. Lane 1, T/P only; lanes 2–21, reactions with the various enzymes, in the absence (even-numbered lanes) or the presence of dNTPs (odd-numbered lanes). The different RTs/DNA polymerases and the presence of Mn⁺² or Mg⁺² (for MLV and Tf1 RTs) are indicated. (A) Assayed with set #1. (B) Assayed with set #2.