ATR-FTIR: a "rejuvenated" tool to investigate amyloid proteins

Abstract

Amyloid refers to insoluble protein aggregates that are responsible for amyloid diseases but are also implicated in important physiological functions (functional amyloids). The widespread presence of protein aggregates but also, in most of the cases, their deleterious effects explain worldwide efforts made to understand their formation, structure and biological functions. We emphasized the role of FTIR and especially ATR-FTIR techniques in amyloid protein and/or peptide studies. The multiple advantages provided by ATR-FTIR allow an almost continuous structural view of protein/peptide conversion during the aggregation process. Moreover, it is now well-established that infrared can differentiate oligomers from fibrils simply on their spectral features. ATR-FTIR is certainly the fastest and easiest method to obtain this information. ATR-FTIR occupies a key position in the analysis and comprehension of the complex aggregation mechanism(s) at the oligomer and/or fibril level. These mechanism(s) seem to present strong similarities between different amyloid proteins and might therefore be extremely important to understand for both disease-associated and functional amyloid proteins. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.

Keywords: 8-anilino-1-naphthalenesulfonic acid; AD; ADDLs; ANS; ATR; Aggregate; Alzheimer's disease; Amyloid; Amyloid beta; Attenuated total reflection; Attenuated total reflection (ATR); Aβ; CD; EM; EPR; FTIR; Fourier-transform infrared spectroscopy; HETs; IAPP; IRE; Islet Amyloid Polypeptide; Oligomer; PrP; PrP(C); PrP(Sc); SDS-PAGE; SH3 domain; Sodium dodecyl sulfate polyacrylamide gel electrophoresis; Src homology 3 domain; TTR; ThT; Thioflavine T; Transthyretin; WB; Western Blot; amyloid-beta derived diffusible ligands; cellular prion protein; circular dichroism; electron microscopy; electron paramagnetic resonance; hIAPP; human Islet Amyloid Polypeptide; internal reflection element; pathological (scrapie) isoform of the prion protein; prion of the filamentous fungus P. anserine; prion protein; solid-state Nuclear magnetic resonance; ssNMR; β-sheet.