Single-Molecule Titration in a Protein Nanoreactor Reveals the Protonation/Deprotonation Mechanism of a C:C Mismatch in DNA.

ABSTRACT: Measurement of single-molecule reactions can elucidate microscopic mechanisms that are often hidden from ensemble analysis. Herein, we report the acid-base titration of a single DNA duplex confined within the wild-type α-hemolysin (α-HL) nanopore for up to 3 h, while monitoring the ionic current through the nanopore. Modulation between two states in the current-time trace for duplexes containing the C:C mismatch in proximity to the latch constriction of α-HL is attributed to the base flipping of the C:C mismatch. As the pH is lowered, the rate for the C:C mismatch to flip from the intra-helical state to the extra-helical state ( kintra-extra) decreases, while the rate for base flipping from the extra-helical state to the intra-helical state ( kextra-intra) remains unchanged. Both kintra-ex

SUBMITTER: Ren H 

PROVIDER: S-EPMC5951715 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature