Effect of peracetylation of lysine in fibrillar WT- and ALS-variant apo-SOD1 on fibril thermostability (i.e., acetylation after fibrillization). (A–C) Mass spectra of unacetylated (left panel), and peracetylated (right panel) WT- and ALS-variant apo-SOD1 thermochemically dissociated from amyloid fibrils (acetylation was performed after fibrillization). (D–F) Thermal stability curves of unacetylated (blue solid squares) and peracetylated (red solid squares) WT, D90A, and A4V apo-SOD1 amyloid fibrils. To see this figure in color, go online.