Figure 5. Small molecule:IAPP binding and structural effects.
(a) Relative binding of ADM-116 to IAPP using 25 nM ADM-116F, and measuring diffusion by fluorescence correlation spectroscopy as a function of [IAPP]. Inset: representative raw autocorrelation data for ADM-116F in the presence of 0 nM and 250 nM IAPP. Fits using a single diffusing species for data at 0 nM IAPP and two diffusing species at 250 nM IAPP are shown in red. The data shown are an average of three experimental repeats. (b) Association constants for the indicated small molecule with human IAPP measured by ITC. Note, undetectable binding indicated with ‘ND'. Inset: representative raw data and fit for ADM-116 binding plotted as a function of stoichiometry. (c) Free energy and entropy contributions to binding by ITC for the indicated compounds. (d) Far-ultraviolet CD spectra of 25 μM IAPP in the presence of LUVs (1.2 mM in monomeric units, DOPG:DOPC, 1:1, 100 nm) expressed as mean residue ellipticity (MRE). Shown are two time points for IAPP alone (blue, black) and with addition of stoichiometric ADM-116 at t=0. ADM-116 without IAPP is shown as control (orange). rel., relative; ND, not detected.