title: Nuclear magnetic resonance evidence for the dimer formation of beta amyloid peptide 1-42 in 1,1,1,3,3,3-hexafluoro-2-propanol.
abstract: Alzheimer's disease involves accumulation of senile plaques in which filamentous aggregates of amyloid beta (Aβ) peptides are deposited. Recent studies demonstrate that oligomerization pathways of Aβ peptides may be complicated. To understand the mechanisms of Aβ(1-42) oligomer formation in more detail, we have established a method to produce (15)N-labeled Aβ(1-42) suited for nuclear magnetic resonance (NMR) studies. For physicochemical studies, the starting protein material should be solely monomeric and all Aβ aggregates must be removed. Here, we succeeded in fractionating a "precipitation-resistant" fraction of Aβ(1-42) from an "aggregation-prone" fraction by high-performance liquid chromatography (HPLC), even from bacterially overexpressed Aβ(1-42). However, both Aβ(1-42) fractions after 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) treatment formed amyloid fibrils. This indicates that the "aggregation seed" was not completely monomerized during HFIP treatment. In addition, Aβ(1-42) dissolved in HFIP was found to display a monomer-dimer equilibrium, as shown by two-dimensional (1)H-(15)N NMR. We demonstrated that the initial concentration of Aβ during the HFIP pretreatment altered the kinetic profiles of Aβ fibril formation in a thioflavin T fluorescence assay. The findings described here should ensure reproducible results when studying the Aβ(1-42) peptide.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Shigemitsu
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan; Research Fellowship for Young Scientists, Japan Society for the Promotion of Science, Tokyo 102-0083, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Iwaya
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Goda
authors.affiliation: Graduate School of Science, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Matsuzaki
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan; Graduate School of Science, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tenno
authors.affiliation: Graduate School of Science, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Narita
authors.affiliation: Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation, Hyogo 650-0047, Japan; Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Minako
authors.initials: M
authors.lastname: Hoshi
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan; Graduate School of Science, Nagoya University, Nagoya 464-8601, Japan. Electronic address: hiroaki.hidekazu@f.mbox.nagoya-u.ac.jp.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Hiroaki
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010446:Peptide Fragments / Q000737:chemistry*; D020005:Propanols / Q000737:chemistry* / Q000494:pharmacology; D066263:Protein Aggregation, Pathological; D055503:Protein Multimerization / Q000187:drug effects; D006845:Hydrocarbons, Fluorinated
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D020005:Propanols; C075222:amyloid beta-protein (1-42); C001337:hexafluoroisopropanol; D006845:Hydrocarbons, Fluorinated
keywords: Alzheimer's disease; Amyloid beta; HFIP; Self-association; Solution NMR