FTIR reveals structural differences between native β-sheet proteins and amyloid fibrils.

The presence of β-sheets in the core of amyloid fibrils raised questions as to whether or not β-sheet-containing proteins, such as transthyretin, are predisposed to form such fibrils. However, we show here that the molecular structure of amyloid fibrils differs more generally from the β-sheets in native proteins. This difference is evident from the amide I region of the infrared spectrum and relates to the distribution of the ϕ/ψ dihedral angles within the Ramachandran plot, the average number of strands per sheet, and possibly, the β-sheet twist. These data imply that amyloid fibril formation from native β-sheet proteins can involve a substantial structural reorganization. [ABSTRACT FROM AUTHOR]