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FT‐Raman spectroscopy as diagnostic tool of Congo red binding to amyloids
Author(s) -
Iconomidou Vassiliki A.,
Chryssikos Georgios D.,
Gionis Vassilis,
Hoenger Andreas,
Hamodrakas Stavros J.
Publication year - 2003
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.10344
Subject(s) - congo red , chemistry , raman spectroscopy , amyloid (mycology) , fibril , spectroscopy , peptide , biochemistry , organic chemistry , inorganic chemistry , adsorption , physics , optics , quantum mechanics
Chorion is the major component of silkmoth eggshell. More than 95% of its dry mass consists of the A and B families of low molecular weight structural proteins, which have remarkable mechanical and chemical properties protecting the oocyte and developing embryo from environmental hazards. We present data from FT‐Raman spectroscopy of silkmoth chorion and amyloid‐like fibrils formed from peptide analogues of chorion proteins, both unstained and stained by Congo red. The results show that FT‐Raman spectroscopy is not a straightforward diagnostic tool for the specific interactions of Congo red with amyloids: a dilute aqueous solution of the Congo red dye at pH 5.5 and a thin solid film of the dye cast from this solution exhibit the same “diagnostic” Raman shifts relative to the neat Congo red dry powder as do amyloid fibrils formed from peptide analogues of chorion proteins stained by Congo red. An important consequence of this finding is that these shifts of the Raman active modes of Congo red are probably due to the formation of supramolecular dye aggregates in the presence of water. Therefore, this is not an appropriate diagnostic test for Congo red binding to amyloids. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 185–192, 2003