Figure 2.
Trapping of DNA and analysis of base flipping at a C:C mismatch site within a DNA duplex. (A) The DNA duplex is driven into the αHL nanopore under an applied potential where it is held for up to 20 s and then ejected by reversing the applied bias. While resident within the pore, the C:C mismatch site is aligned with the latch constriction of αHL. (B) Modulating current signatures are observed while DNA resides within the nanopore, where I1 corresponds to a confirmation where all bases are intrahelical and I2 corresponds to a conformation where one of the cytosine bases at the mismatch site is extrahelical. Intra- and extrahelical lifetimes are given by t1 and t2, respectively. Uninterrupted current-time traces demonstrating sequential capture and release of multiple DNA duplexes are shown in Figures S1 and S2.