Influence of Salt on the Self-Assembly of Two Model Amyloid Heptapeptides

Abstract

We study the effects of NaCl on the self-assembly of AAKLVFF and betaAbetaAKLVFF in solution. Both AAKLVFF and betaAbetaAKLVFF self-assemble into twisted fibers in aqueous solution. The addition of NaCl to aqueous solutions of AAKLVFF produces large crystal-like nanotapes which eventually precipitate. In contrast, highly twisted fibrils were observed for betaAbetaAKLVFF solutions at low salt concentration, while a coexistence of highly twisted fibers and nanotubes was observed for betaAbetaAKLVFF at high salt concentration. The self-assembled structures observed for betaAbetaAKLVFF in NaCl solutions were ascribed to the progressive screening of the betaAbetaAKLVFF surface charge caused by the addition of salt.

Therapeutic implication of L-phenylalanine aggregation mechanism and its modulation by D-phenylalanine in phenylketonuria

“…5a) due to increase in hydrophobic interactions3334. With increase in ionic strength, particle size increased due to salt induced charge suppression, leading to effective hydrophobic interactions3536.…”

“…Self-association of this molecule into ThT positive assembly revealed the importance of hydrophobic interactions. Moreover, increase in particle size with increase in ionic strength and temperature strengthens the involvement of hydrophobic interactions33343536. Interestingly, the inability of PG to form gel clearly indicates that methylene group in Phe provides more flexibility, hydrophobicity and orientation to ring structure to favour stacking interactions to form fibrous gel.…”

Oligomer Formation of Toxic and Functional Amyloid Peptides Studied with Atomistic Simulations

“…29,31,[78][79][80] To study the influence of salt concentration, we repeated the simulations for Aβ 25−35 and the tachykinin peptides with a NaCl concentration of 150 mM. Figure 1c shows the aggregation of the three peptides at high salt concentration.…”

Advances in cryogenic transmission electron microscopy for the characterization of dynamic self-assembling nanostructures

“…In addition to pH, the influence of salt on the self-assembly of Aβ peptides has also been investigated. Castelletto and coworkers observed that addition of NaCl to NH 2 -βAβAKLVFF-COOH peptides, a key sequence involved in Aβ fibril formation, resulted in the conformational change of the fibrils from thin nanoribbons to the coexistence of wide, twisted fibers and nanotubes [101]. They proposed that salt enhanced the twisting of fibers by screening the charge both at the β-sheet surface and at the edges of the twisted tapes.…”