19 research outputs found

    Force Spectroscopy Setup.

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    <p>A schematic of experimental setup of force spectroscopy experiment showing Aβ bound to substrate and tip via the PEG linker.</p

    Schematic diagram of Aβ dimers with and without copper.

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    <p>Without copper, the most favorable conformation of the Aβ dimer involves an anti-parallel conformation (A). With the addition of copper, Aβ adopts a parallel dimer conformation (B) stabilized by the occupied copper binding sites (C).</p

    AFM images of amyloid-metal aggregates.

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    <p>AFM images of Aβ incubated without copper for periods of 1 hr (A) 6 hr (B) and 24 hr (C), and with copper at a 10∶1 molar ratio for 1 hr (D), 6 hr (E), and 24 hr (F). The lateral scale bar is 1 µm.</p

    Representative force curves.

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    <p>Force curves showing rupture forces of an Aβ dimer without (A) and with (B) copper added at a retraction rate of 400 nm/s. Curves are shown as force vs. piezo z-displacement.</p

    Proposed structures of Aβ dimers with and without copper assembled from stable Aβ(1–42) monomer structures.

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    <p>Each monomer has an internal antiparallel β-sheet between residues 18–21 and 30–33. The dimers are assembled by juxtaposition of the self-recognition site residues 18–21 in antiparallel (A, C) and parallel (B, D) orientation. Both orientations bring His6, His13 and His14 of each monomer into close proximity, requiring little reorientation to bind Cu<sup>2+</sup> ions (filled green circles). Structures are courtesy of D. F. Raffa and A. Rauk, Molecular Dynamics Study of the Beta Amyloid Peptide of Alzheimer's Disease and its Divalent Copper Complexes <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059005#pone.0059005-Raffa1" target="_blank">[53]</a>, created using Raswin software.</p

    Effect of Copper on Aβ rupture force.

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    <p>Histograms show the distribution of forces required to rupture the Aβ-Aβ complex without copper (A) and with copper (B). Fits to the data are Gaussian distributions, the peaks of which represent the most probable rupture force.</p

    Statistical Data of Force Spectroscopy Experiments.

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    <p>Statistical Data of Force Spectroscopy Experiments.</p

    AFM topography images of Aβ (1–42) incubated in solution (500 µg/mL concentration) at 37°C for 22 hours.

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    <p>After incubation, 10 µL of solution was deposited onto cleaved mica for 5 minutes, followed by rinsing with nanopure water and drying with a gentle nitrogen stream. A 10×10 µm scan area (A) of the surface shows many fibrils ranging from 0.1 – 4 µm. (B) High resolution image (500×500nm) demonstrates that fibrils reveal twisted morphologies, characteristic of formed in solution; (below, left) expanded view of region enclosed by white box in (B) with optimized z-scale; (below, right) height profile along fibril axis clearly demonstrating maxima and minima which is characteristic of the twisted morphology.</p

    Statistical analysis of Aß small aggregates shown in <b>figure 3</b>.

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    <p>Histograms of aggregate unit area size (A, C, E) and height of each aggregate (B, D, F) for each surface type; (Red) CH<sub>3</sub>-modified surface; (green) COOH-modified surface; (blue) NH<sub>2</sub>-modified surface.</p

    AFM topography images (5×5 µm) of the amyloid fibrils formed on CH<sub>3</sub>, NH<sub>2</sub>, and COOH –modified surfaces.

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    <p>Aß peptide solution was incubated for 22 hours at 37°C on: (A) CH<sub>3</sub>-, (B) NH<sub>2</sub>-, and (C) COOH-modified surfaces.</p
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