Figure 2.

Manufacturer- and solvent-effects on FPR activation by Aβ_1-42.A, left: Schematic depiction of ThT aggregation assay. Right: Mean fluorescence of 22.5 μM Aβ_1-42 in C1 buffers from different manufacturers in a ThT aggregation assay during the first 10 min (clear bars) versus fluorescence after 120 min (striped bars). Buffer refers to ThT fluorescence without addition of peptides (gray bars). All n = 3, N = 3, except for Sigma and Anaspec with n = 2, N = 3; One-way ANOVA test, Dunnett post hoc test. B, mean Ca²⁺ peak responses of human (red) or mouse (blue) FPRs to 10 μM of Aβ_1-42 peptides obtained from Peptides & Elephants (P&E) and Synpeptide; n = 3, N = 2, One-way ANOVA test, Dunnett post hoc test in comparison to respective buffer controls. C, heat map of mean Ca²⁺ responses of FPRs elicited by Aβ_1-42 peptides obtained from five different manufacturers. The scale ranges from white (no response) to deep orange (ΔF/F0 ≥ 0.4). Responses are shown in Figure S1B. D, secondary structure composition of four Aβ_1-42 peptides analyzed by circular dichroism (CD) spectroscopy; n = 3, N = 1; One-way ANOVA test, Tukey post hoc test. E, mean Ca²⁺ peak responses of cells transfected with human FPRs (red) or mock (gray) towards 5 μM Aβ_1-42 dissolved in the respective buffers; n = 3, N = 1, One-way ANOVA test, Dunnett post hoc test. F, comparison of ThT fluorescence of Aβ_1-42 (P&E) dissolved in either C1, dimethyl sulfoxide (DMSO), Tris–NaCl, or HBSS. All assays were performed in the respective buffers. For experiments with peptides predissolved in DMSO, assays were conducted in C1 with a final concentration of DMSO: 0.2% (V/V). One-way ANOVA test, Dunnett post hoc test. All Error bars, S.D.; ∗p ≤ 0.05; ∗∗p ≤ 0.01; ∗∗∗p ≤ 0.001; ns, no significance. Aβ, amyloid beta; FPR, Formyl peptide receptor; ThT, thioflavin T.