Congo red dichroism with dispersed amyloid fibrils, an extrinsic cotton effect
TLDR
Extension of the use of polarization microscopy with other dyes that bind to other substances in tissue sections should permit more exquisite probing of the conformation of important macromolecules in situ in cells and tissues than has hitherto been possible.Abstract:
The spectral absorption, optical rotatory dispresion, and circular dichroism associated with interaction of Congo red dye with partly purified suspensions of amyloid fibril fragments were examined. A set of phenomena consistent with a Cotton effect was found. A nearly identical set of phenomena was obtained with poly-L-lysine in its α-helical form. The dichroism seen when Congo red binds to amyloid substance in tissue sections can also be interpreted as a Cotton effect. This suggests that some special conformation, presumably in protein, is present in a major constituent of amyloid. This conformation is not present in gamma globulin, Bence-Jones protein, albumin, fibrinogen, or other proteins tested so far. These and other optical properties of amyloid substance can be used to compare amyloid deposits in different human cases and in different species. Extension of the use of polarization microscopy with other dyes that bind to other substances in tissue sections should permit more exquisite probing of the conformation of important macromolecules in situ in cells and tissues than has hitherto been possible.read more
Citations
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Binding mode of Thioflavin T and other molecular probes in the context of amyloid fibrils—current status
Minna Groenning,Minna Groenning +1 more
TL;DR: Increased understanding of present molecular probes as well as development of new probes are of utmost importance for development of strategies to control amyloid formation and overcome neurodegenerative disorders.
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Identification of a penta- and hexapeptide of islet amyloid polypeptide (IAPP) with amyloidogenic and cytotoxic properties.
Konstantinos Tenidis,Michaela Waldner,Jürgen Bernhagen,Wolfgang Fischle,Michael Bergmann,Marco Weber,Marco Weber,Marie-Luise Merkle,Wolfgang Voelter,Herwig Brunner,Aphrodite Kapurniotu +10 more
TL;DR: The results suggest that a penta- and hexapeptide sequence of an appropriate amino acid composition can be sufficient for beta-sheet and amyloid fibril formation and cytotoxicity and may assist in the rational design of inhibitors of pancreatic amylidosis-related diseases.
Journal ArticleDOI
Is Congo Red an Amyloid-specific Dye?
TL;DR: The data suggest that Congo red is sandwiched between two protein molecules causing protein oligomerization, which shows that it must be used with caution as a diagnostic test for the presence of amyloid fibrils in vitro.
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Are the polarization colors of picrosirius red-stained collagen determined only by the diameter of the fibers?
TL;DR: Polarization colors of various purified collagens were studied in fibers of similar thickness and suggested that fiber thickness was not the only factor involved in determining the polarization colors of Picrosirius red-stained collage.
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Congo Red and amyloids: history and relationship
TL;DR: The characteristics and limitations of other methods used for amyloid studies are described, to provide insight into the pitfalls and caveats related to this technique for researchers considering using this dye.
References
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X-ray diffraction studies on amyloid filaments
E. D. Eanes,G. G. Glenner +1 more
TL;DR: The filamentous protein component of amyloid-laden tissue was studied by x-ray diffraction procedures and it is suggested that the axes of the chain segments run transverse to the filament axis.
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TL;DR: Amyloid was extracted from the spleen of a patient with primary amyloidosis by homogenizing it at high speed with water after preliminary treatments, first to remove proteins soluble in saline, and then to remove salts.
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The Conformational Transitions of Uncharged Poly-L-lysine. α Helix-Random Coil-β Structure*
Betty Davidson,Gerald D. Fasman +1 more
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Characterization of the amyloid fibril as a cross-beta protein.
TL;DR: Whether this molecular structure was consistently present in all preparations, including those freed from the pentagonal unit, was determined to be consistently present.