Activity of R. BsaHI Mutants. Agarose gel electrophoresis of λ-DNA digested with R. BsaHI mutants. Lane 1 contains the NEB 2-log DNA marker. Control digests were run using the Puresystem without bsaHIR gene (lane -bsaHIR) and with the wild-type bsaHIR gene (lane WT). The remaining lanes are labelled by the amino acid that was mutated to alanine. In all lanes of the gel shown in Figure 4, there is some RNA impurity, resulting from the IVTT mixture. This is seen as a series of diffuse bands running at less than 500 base pairs in length.