**2.1 HEWL solution preparation**

Lysozyme was dissolved (25 mg/mL) in 20% acetic acid and 100 mM NaCl at pH 2.0 and incubated at 60°C to form fibrils under initial (control) conditions. To study the effect of H2S, sodium sulfide nonahydrate salt (12 mM) was added to the control solution in a molar ratio of 1:5 (HEWL:H2S), prior to the temperature elevation.
