Fig. 5.

One-site reactions. The reactions contained, in reaction buffer at 50 °C, 5 nM [³H]pGB1/S1 (a plasmid with one SfiI site, initially 90–95% SC monomer), and either wt SfiI (red circles) or Y68F (blue circles) at one of the following concentrations: (a) 0.05 nM enzyme; (b) 0.5 nM enzyme; (c) 1.5 nM enzyme. The reactions were carried out and analysed as in Figure 4 to determine the residual concentrations of the SC DNA substrate.