ΔI(t) excursions during native and analog dNTP incorporation. High and low current states correspond to conformational dynamics of the enzyme during processive nucleotide incorporation. (a) In the presence of poly(dC)42 template and its complementary native dGTP, ΔI(t) excursions occur during each base incorporation. (b) Magnification of the highlighted region in (a) illustrates the ΔI(t) events corresponding to single base incorporations. For comparison, representative 1 s data sets are shown for the same KF nanocircuit incorporating the dNTP analogs (c) αthio-dGTP, (d) 6-Cl-2APTP, and (e,f) 2-thio-dCTP. To the right of each data set, the magnified view depicts one typical ΔI(t) excursion.