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International Journal of Alzheimer’s Disease
Volume 2011, Article ID 925073, 8 pages
http://dx.doi.org/10.4061/2011/925073
Research Article

Spectroscopic Characterization of Intermolecular Interaction of Amyloid β Promoted on GM1 Micelles

1Graduate school of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
2Institute for Molecular Science and Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
3Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
4Department of Alzheimer's Disease Research, National Center for Geriatrics and Gerontology, National Institute for Longevity Sciences, 36-3 Gengo, Morioka, Obu, Aichi 474-8522, Japan

Received 13 October 2010; Revised 30 November 2010; Accepted 3 December 2010

Academic Editor: J. Fantini

Copyright © 2011 Maho Yagi-Utsumi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Clusters of GM1 gangliosides act as platforms for conformational transition of monomeric, unstructured amyloid β (Aβ) to its toxic β-structured aggregates. We have previously shown that Aβ(1–40) accommodated on the hydrophobic/hydrophilic interface of lyso-GM1 or GM1 micelles assumes α-helical structures under ganglioside-excess conditions. For better understanding of the mechanisms underlying the α-to-β conformational transition of Aβ on GM1 clusters, we performed spectroscopic characterization of Aβ(1–40) titrated with GM1. It was revealed that the thioflavin T- (ThT-) reactive β-structure is more populated in Aβ(1–40) under conditions where the Aβ(1–40) density on GM1 micelles is high. Under this circumstance, the C-terminal hydrophobic anchor Val39-Val40 shows two distinct conformational states that are reactive with ThT, while such Aβ species were not generated by smaller lyso-GM1 micelles. These findings suggest that GM1 clusters promote specific Aβ-Aβ interactions through their C-termini coupled with formation of the ThT-reactive β-structure depending on sizes and curvatures of the clusters.