Evidence of Ph-Based Differential Effect of Dtt On in Vitro Amyloidogenesis of Hen Egg-White Lysozyme

Abstract

Proteins, under certain environmental conditions, have the tendency to undergo a conformational change from their native, folded state to a state characterized by the formation of fibrillar aggregates featuring a cross β-sheet structure, known as amyloids. These amyloid aggregates have been closely associated with various disorders. One pivotal factor influencing the propensity for aggregation in proteins is the presence of disulfide bonds. Here, we utilized Hen Egg White Lysozyme (HEWL) as a model protein to unravel the significance of disulfide bonds in the formation of amyloid fibrils. We employed Dithiothreitol (DTT) as a reducing agent under two distinct pH conditions, pH 2.7 and pH 7.4, to explore how DTT affects HEWL amyloid formation, contingent on the pH level and the choice of buffer for preparing the amyloid fibrils. Our investigations underscore the critical role played by non-native disulfide bonds in the process of amyloidogenesis, demonstrating how the disruption of these bonds can significantly influence the fibrillation process. Overall, our findings shed light on the mechanisms underlying fibrillation and offer valuable insights that can be further harnessed for the development of effective inhibitors against amyloidosis