Fibril Structure of Abeta40 Visualized by Cryo-Electron Microscopy and Solid-State NMR

Amyloids are implicated in neurodegenerative diseases. Fibrillar aggregates of the amyloid-β protein (Aβ) are the main component of the senile plaques found in brains of Alzheimer’s disease patients. We present the structure of an Aβ(1–42) fibril composed of two intertwined protofilaments determined by cryo–electron microscopy (cryo-EM) to 4.0-angstrom resolution, complemented by solid-state nuclear magnetic resonance experiments. The backbone of all 42 residues and nearly all side chains are well resolved in the EM density map, including the entire N terminus, which is part of the cross-β structure resulting in an overall “LS”-shaped topology of individual subunits. The dimer interface protects the hydrophobic C termini from the solvent. The characteristic staggering of the nonplanar subunits results in markedly different fibril ends, termed “groove” and “ridge,” leading to different binding pathways on both fibril ends, which has implications for fibril growth.

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Characterization of beta-Silicon Carbide by Silicon-29 Solid-State NMR, Transmission Electron Microscopy, and Powder X-ray Diffraction

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.1990.tb07589.x ◽

1990 ◽

Vol 73 (8) ◽

pp. 2281-2286 ◽

Cited By ~ 44

Author(s):

Keith R. Carduner ◽

Sam S. Shinozaki ◽

Michael J. Rokosz ◽

Charles R. Peters ◽

Thomas J. Whalen

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Silicon Carbide ◽

Solid State ◽

Solid State Nmr ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron

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Pressure Induced Disorder in Kaolinite

Clay Minerals ◽

10.1180/claymin.1993.028.2.11 ◽

1993 ◽

Vol 28 (2) ◽

pp. 311-319 ◽

Cited By ~ 11

Author(s):

A. La Iglesia

Keyword(s):

Electron Microscopy ◽

Solid State ◽

Solid State Nmr ◽

Gradual Increase ◽

Grinding Process ◽

Pressure Treatment ◽

Process Pressure ◽

Two Samples ◽

Oh Content ◽

Increased Pressure

AbstractChanges caused by pressures between 0 and 20 K bar on two samples of kaolinite have been studied. Increased pressure causes the samples to lose crystallinity, shown by a decrease in the Hinckley, Lietard and reference intensity ratio indices, as well as by the crystallite size measured from the 001 reflection. Results from DTA and solid state NMR show slight or no differences between the compressed and natural samples. Nonetheless, thermogravimetry reveals that the pressure treatment lowers the temperature at which dehydroxylation begins, but, unlike the grinding process, pressure does not alter the OH content of the samples. As a result of the increase in pressure, the IR spectra of the samples show a gradual increase in the intensity of the band at 1104 cm -1 with respect to 1112 cm -1. An increase in intensity can also be observed in the band at 936 cm ~ with respect to the band at 912 cm -1. Examination by electron microscopy reveals the existence of a large number of defects such as fractures, bends and deformations of the sheets, etc.; these are responsible for the decrease in crystallinity.

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