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Related Concept Videos

Amyloid Fibrils03:03

Amyloid Fibrils

Amyloid fibrils are aggregates of misfolded proteins.  Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils. 
Amyloid deposits were observed as early as 1639 in the liver and the spleen.   In 1854, Rudolph Virchow performed iodine staining, normally used to...
Amyloid Fibrils03:03

Amyloid Fibrils

Amyloid fibrils are aggregates of misfolded proteins.  Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils. 
Amyloid deposits were observed as early as 1639 in the liver and the spleen.   In 1854, Rudolph Virchow performed iodine staining, normally used to...
X-ray Diffraction of Biological Samples01:10

X-ray Diffraction of Biological Samples

X-ray diffraction or XRD is an analytical tool that utilizes X-rays to study ordered structures such as crystalline organic and inorganic samples, polycrystalline materials, proteins, carbohydrates, and drugs.
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are  scattered by the electron clouds around the sample atoms. The  X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
Antifungal Agents01:15

Antifungal Agents

Amphotericin B is a broad-spectrum antifungal agent that exploits structural differences between fungal and mammalian cell membranes. Its amphipathic structure—featuring a hydrophobic polyene-lactone ring and a hydrophilic region containing mycosamine and carboxylic acid groups—enables selective binding to ergosterol, a sterol predominantly found in fungal plasma membranes. This selective interaction underlies the drug’s antifungal activity, although weak binding to cholesterol contributes to...

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Related Experiment Video

Updated: Jul 4, 2026

Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging
10:04

Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging

Published on: October 20, 2017

Fiber diffraction as a screen for amyloid inhibitors.

Daniel A Kirschner1, Abby A R Gross, Marla M Hidalgo

  • 1Biology Department, Boston College, Chestnut Hill, MA 02467, USA. kirschnd@bc.edu

Current Alzheimer Research
|June 10, 2008
PubMed
Summary

This study used fiber X-ray diffraction to analyze how small molecules affect amyloid fiber formation, a key process in neurodegenerative diseases. PTI-00703 was found to be particularly effective at disrupting amyloid hydrogen bonds, offering insights for new therapeutic strategies.

More Related Videos

Analysis of β-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy
06:27

Analysis of β-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy

Published on: November 30, 2018

Related Experiment Videos

Last Updated: Jul 4, 2026

Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging
10:04

Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging

Published on: October 20, 2017

Analysis of β-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy
06:27

Analysis of β-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy

Published on: November 30, 2018

Area of Science:

  • Biophysics
  • Structural Biology
  • Neurodegenerative Diseases

Background:

  • Amyloid assemblies, implicated in diseases like Alzheimer's, are targeted therapeutically at their initial oligomeric stages before fiber formation.
  • Amyloid fibers exhibit characteristic X-ray diffraction patterns with maxima at 4.7 Å (beta-chain spacing) and ~10 Å (beta-pleated sheet spacing).
  • Understanding the structural impact of small molecules on amyloid formation is crucial for developing effective inhibitors.

Purpose of the Study:

  • To apply fiber X-ray diffraction to monitor structural indicators of amyloid fiber assembly in the presence of various small aromatic molecules.
  • To characterize the effects of these molecules on the aggregation of different amyloid-beta (Abeta) peptide analogues.
  • To evaluate the efficacy of identified inhibitors based on crystallite volume and their mechanism of action (hydrogen bonding vs. intersheet interactions).

Main Methods:

  • Fiber X-ray diffraction was employed to analyze amyloid assemblies (Abeta1-40, Abeta11-25, etc.) with and without a panel of small molecules.
  • Key structural parameters, including integral widths and integrated intensities of characteristic X-ray reflections, were measured.
  • The effects of small molecules on hydrogen-bonding and intersheet spacing were assessed, and crystallite volumes were calculated.

Main Results:

  • Most small molecules showed varying effects on relative intensities but similar coherent lengths; however, PTI-00703 abolished the hydrogen-bonding reflection.
  • PTI-00703, tannic acid, and quinine were identified as more effective inhibitors of Abeta11-25 aggregation than curcumin, morin, and melatonin, based on crystallite volume.
  • Increased concentration of N-methylated Abeta16-22 led to decreased beta-crystallite volumes, suggesting binding to monomers or oligomers.

Conclusions:

  • Fiber X-ray diffraction is a valuable tool for characterizing the structural impact of small molecules on amyloid formation.
  • The method can differentiate whether a compound inhibits amyloidogenesis by affecting hydrogen bonding or intersheet interactions.
  • Findings provide a rational basis for developing novel therapeutic agents targeting specific structural aspects of amyloid assembly.