Figure 4.
Effect of the tag charge on the dwell time of DHFRNtagO2. (a) Surface representations of all DHFRNtagO2 mutants going from Ntag = 4 (top) to Ntag = 9 (bottom). The positively charged residues in the tag have been annotated and highlighted in blue. (b) Voltage dependencies of the mean dwell time (td) for the mutant on the left-hand side, fitted with the double barrier model of eq 6. The annotated threshold voltages were computed by Supporting Information eq S26. Solid lines represent the double barrier dwell time, and the dotted lines show the dwell times due the cis (low to high) and trans (high to low) barriers. Fitting parameters can be found in Table 2. The error envelope represents the minimum and maximum values obtained from repeats at the same condition. Experimental conditions are the same as those in Figure 3.