Structural stability of amyloid fibrils depends on the existence of the peripheral sequence near the core cross-β region

Amyloid fibrils are fibrous protein assemblies with distinctive cross-β structures. For amyloidosis, there are disease-associated mutations outside of the cross-β structures. Thus, it is necessary to elucidate the role of peripheral sequences outside the cross-β structure. Amyloid fibrils are generally 10 nm in width; however, the amyloid fibrils of truncated barnase M1 peptides missing the C-terminal sequence outside the cross-β structure are 20 nm in width. In this study, we performed comparative analysis of the structural stability of amyloids formed by the respective peptides. We found that the C-terminal amino acids dramatically affect the conformational instability in the presence of a denaturing reagent.