Exploring the role of ethylammonium bromide as an ionic liquid in amyloid aggregation modulation for ALS-linked hSOD1 E49K mutant.

Ionic liquids (ILs) offer a diverse and tunable approach to inhibiting amyloid protein formation, providing new strategies to develop anti-amyloidogenic agents for amyloid-based diseases, as explored in protein-IL research. This study explores the formation of amyloid aggregates of the E49K mutant under amyloidogenic conditions and evaluates the inhibitory potential of ethylammonium bromide (EABr) as an anti-amyloidogenic agent relevant to ALS pathology. The effect of EABr was studied using molecular dynamics simulations, FTIR spectroscopy, ANS fluorescence, ThT fluorescence, and TEM imaging. EABr promotes the formation of compact structures by reducing the exposure of contagious hydrophobic pockets in the E49K mutant aggregates, as monitored by ANS fluorescence. EABr binds with moderate affinity to the E49K mutant forms, inhibiting fibrillation by stabilizing aggregation-prone regions, as shown in fluorescence quenching. The decrease in ThT fluorescence intensity and the inhibition of fibril formation in a concentration-dependent manner highlight the interaction of EABr with the E49K mutant throughout the incubation period. TEM images during the saturation phase provide compelling evidence that EABr inhibits the formation of amyloid fibrils in the E49K mutant, thus supporting ThT analysis results. These findings demonstrate that EABr can inhibit amyloid formation of the E49K SOD1 mutant in vitro, supporting its potential as a lead compound for further pharmacological studies.