Investigation of the binding of Congo red to amyloid in Alzheimer's diseased tissue

Infrared, Raman and UV-visible spectroscopic techniques were used to investigate the chemical mechanism of binding of the marker dye Congo red to deposits of Alzheimer's amyloid in cerebral tissue. Results show that the interaction is the same in diseased brain tissue as in the case of model proteins. This mechanism involves bonding between the SO; groups of the dye and positive fractions in the peptide, as well as less well-defined interactions involving the conjugated ring system of the dye molecule. (C) 1997 Elsevier Science B.V.