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" Nanoprobing of the effect of Cu(2+) cations on misfolding, interaction and aggregation of amyloid β peptide. "
Lv, Zhengjian; Condron, Margaret M; Teplow, David B; Lyubchenko, Yuri L
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AL
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| Record Number
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909319
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LA7p75j3tx
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| Title & Author
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Nanoprobing of the effect of Cu(2+) cations on misfolding, interaction and aggregation of amyloid β peptide. [Article]\ Lv, Zhengjian; Condron, Margaret M; Teplow, David B; Lyubchenko, Yuri L
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2013
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| Title of Periodical
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UCLA
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| Abstract
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Misfolding and aggregation of the amyloid β-protein (Aβ) are hallmarks of Alzheimer's disease. Both processes are dependent on the environmental conditions, including the presence of divalent cations, such as Cu(2+). Cu(2+) cations regulate early stages of Aβ aggregation, but the molecular mechanism of Cu(2+) regulation is unknown. In this study we applied single molecule AFM force spectroscopy to elucidate the role of Cu(2+) cations on interpeptide interactions. By immobilizing one of two interacting Aβ42 molecules on a mica surface and tethering the counterpart molecule onto the tip, we were able to probe the interpeptide interactions in the presence and absence of Cu(2+) cations at pH 7.4, 6.8, 6.0, 5.0, and 4.0. The results show that the presence of Cu(2+) cations change the pattern of Aβ interactions for pH values between pH 7.4 and pH 5.0. Under these conditions, Cu(2+) cations induce Aβ42 peptide structural changes resulting in N-termini interactions within the dimers. Cu(2+) cations also stabilize the dimers. No effects of Cu(2+) cations on Aβ-Aβ interactions were observed at pH 4.0, suggesting that peptide protonation changes the peptide-cation interaction. The effect of Cu(2+) cations on later stages of Aβ aggregation was studied by AFM topographic images. The results demonstrate that substoichiometric Cu(2+) cations accelerate the formation of fibrils at pH 7.4 and 5.0, whereas no effect of Cu(2+) cations was observed at pH 4.0. Taken together, the combined AFM force spectroscopy and imaging analyses demonstrate that Cu(2+) cations promote both the initial and the elongation stages of Aβ aggregation, but protein protonation diminishes the effect of Cu(2+).
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