DNA minor-groove binder Hoechst 33258 destabilizes base-pairing adjacent to its binding site

摘要

a Temperature-ramp FTIR spectra from 5 to 100 °C. b 2D-IR surfaces of DNA and H-DNA measured at 70 °C with parallel polarization. c The difference spectra between 85 and 70 °C surfaces. d Melting curve obtained with SVD analysis of the FTIR spectra for 1 mM DNA and 1 mM H-DNA (circles) and normalized temperature-dependent fluorescence intensity at 446 nm for 200 nM and 2 μM H-DNA (diamonds). The fitted curves obtained from a two-state model are shown with black solid lines. e Transient 2D-IR spectra of native DNA at 500 ns and 1 ms and H-DNA spectra at 500 ns and 4 ms, measured at Ti = 70 °C and Tf = 85 °C with parallel polarization. The spectral feature associated with the loss of A:T base pairs is outlined with a yellow box.