FIG. 3.

Purification and activity of the His-Tth polymerase overexpressed in T. thermophilus. (A) A sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel is shown with fractions corresponding to an affinity Ni-agarose column in which the soluble fraction corresponding to the 4-h lane of Fig. 2A was assayed. The unbound material (E) and fractions corresponding to washing steps with the indicated concentrations of imidazole are shown. Lane M, protein markers of the labeled sizes (in kilodaltons). (B) Amplification of the kat gene with okat3 and okat4 primers. Lane 1, negative control without enzyme; lane 2, commercial Tth DNA polymerase; lane 3, His-tagged Tth DNA polymerase purified from T. thermophilus.