Fig. 1: Characterization of the membrane-associated Aβ_1-42 assembling.

A ThT fluorescence (left y-axis) and CD intensity at 218 nm (right y-axis) along the incubation of membrane-associated Aβ_1-40 (10 μM, top) and Aβ_1-42 (5 μM, bottom). Red curves show sigmoidal fitting of ThT kinetics to the equation \({I}_{t}={I}_{0}+({I}_{\infty }-{I}_{0})[1-\exp \left(-{\left({kt}\right)}^{n}\right)]\), from which the lag periods were derived. The blue curves and dashed lines show the same sigmoidal fitting for the time-dependent CD intensities and the derived \({{{\rm{t}}}}_{1/2}\) values, where \({{{\rm{I}}}}_{{{\rm{t}}}}-{I}_{0}\equiv \frac{1}{2}\left({I}_{\infty }-{I}_{0}\right)\). B Representative ¹³C-PITHIRDs-CT spectra for residues A2 and A30 with 3- and 15-h incubation in POPC liposomes. ¹³C-¹³C dipolar evolution times were given on top of the spectra. C Plots of corrected residue-specific ¹³C-PITHIRDs-CT dephasing curves (see S.I. for the natural abundance correction) at different incubation times. Color-coding: black, 3 h; red, 6 h; blue, 9 h; orange, 12 h; purple, 15 h. Error bars represent the signal-to-noise levels of individual sets of ¹³C-PITHIRDs-CT spectra. D Contour plots for the fitting of ¹³C-PITHIRDs-CT dephasing results using SIMPSON (details provided in S.I.). Contour levels show 1-7 times of \(\sigma \equiv \sqrt{2(N-n)}\) around \({{{\rm{\chi }}}}_{\min }^{2}\), where N is the number of data points \((N=7)\) and n is number of fitting parameters \((n=2)\).