Figure 7.

Compact tetramers divert assembly to WL fibrils at pH 2.5. The LS fibril-assembly of β₂m was initiated (β₂m 0.4 mg mL⁻¹ based on monomer; pH 2.5) and then subjected to increasing buffer concentrations. (A) Thioflavin-T fluorescence analyses showing the spontaneous formation of WL fibrils with >300 mM ammonium formate buffer; (B–D) ESI-IMS-MS driftscope plots showing β₂m oligomers at t = 1 min during fibril assembly with increasing ammonium formate buffer (B, 100 mM; C, 200 mM, and D, 400 mM). The numbers above each peak indicate the oligomer size. The +7 and +8 charge-state ions of the tetramer are highlighted to show their increase in their population with increasing ionic strength.