Fig. 3.

Fraction of ssDNA bound by A3G over time during incubation and dissociation. a During incubation (at 50 nM in sample data), the amount of A3G bound increases monotonically before asymptotically reaching an equilibrium value. As compared with the binding of FW mutant, binding of WT A3G does not reach full saturation even at long incubation times and high A3G concentrations. The binding kinetics cannot be represented as a single exponential function consistent with a simple one step binding system. Instead, two binding rates are used to fit the binding curve (k _fast and k _slow), as predicted by the two step binding model. b During dissociation in buffer (after 200 s incubation time in sample data), only a fraction of the bound A3G unbinds from the ssDNA. More A3G remains bound for WT A3G as compared with FW mutant. Only one rate (k ₋₁) is needed to fit the dissociation curves for both WT and mutant A3G. After equal incubation times, a smaller fraction of FW mutant A3G has formed oligomers as compared with WT