NOVEL CYANINE DYES AS POTENTIAL AMYLOID PROBES: A FLUORESCENCE STUDY

Abstract

The applicability of the novel heptamethine cyanine dyes AK7-5 and AK7-6 to the detection and characterization of one-dimensional protein aggregates (amyloid fibrils) associated with numerous pathologies has been evaluated using the method of fluorescence spectroscopy. It was found that both the monomeric and aggregated forms of these dyes can bind to amyloidogenic protein lysozyme, but the concomitant changes in the electronic structure of H-aggregates render them capable of fluorescing. The growth of the hypsochromic bands with negligible changes of the monomeric peaks induced by the native protein and the opposite effects induced by the lysozyme fibrils suggest that the native lysozyme has more binding sites for the dye aggregates than fibrillar protein, while the fibril grooves represent specific binding site for the dyes monomers. The observed spectral behavior of the cyanine dyes, viz. significant distinctions in the fluorescence responses produced by the monomeric and fibrillar forms of lysozyme, suggest the possibility of recruiting these compounds as fluorescent amyloid markers along with the classical amyloid marker Thioflavin T.

Keywords

• Heptamethine cyanine dyes
• amyloid marker
• H-aggregates
• fluorescence
• lysozyme
• amyloid fibrils