Observation of multi-step conformation switching in β-amyloid peptide aggregation by fluorescence resonance energy transfer

Abstract

We have observed the conformation switching of Aβ11-25 in the course of amyloid aggregation by employing time-resolved fluorescence resonance energy transfer (FRET). The amyloid peptides undergo multi-step conformational changes during self-assembling such as random coil (monomers), collapsed coil (multimers), micellar structure, and extended β-sheet in fibrils. We first identified the critical micelle concentration of Aβ 11-25 that occurs at ca. 3μM for pH 5.0 and ca. 70μM for pH 7.4. Our experimental results show clearly that the end-to-end distance of micellar Aβ11-25 becomes much shorter than that of the collapsed coil or fibril structure. © 2004 Elsevier Inc. All rights reserved.