ИСТИНА

Thioflavin T (ThT) fluorescence is a proven method to detect amyloid fibrils that formation frequently accompany the development of many serious human diseases, including Alzheimer's, Parkinson's, prion, and many other diseases. Despite the obvious advantages of ThT for amyloid fibrils testing in vitro, the spectral properties of this dye restrict its applicability for testing of amyloid plaques in the cells and tissues. We investigated the properties and interaction to amyloid fibrils of a new benzothiazol dye trans-2-[4-(dimethylamino) styryl]-3-ethyl-1,3- benzothiazolium perchlorate (DMASEBT), which has a similar molecular structure with ThT, but differs from it by the length of the chain connecting the benzthiazol and aminobenzene rings, by the absence of a methyl group at the C2 atom and the replacement of the methyl group at the N7 atom of the benzothiazol ring by the ethyl group. Quantum-chemical calculations and spectral studies found that DMASEBT (like ThT) has properties of a molecular rotor. Interaction of DMASEBT with insulin amyloid fibrils is characterized by a high binding constant and a significant increase in fluorescence quantum yield of the dye, which are important properties of the fluorescent probe. In addition, the absorption and fluorescence spectra of DMASEBT bound to fibrils are significantly shifted to longer wavelengths (to the "transparency window" of biological tissues) in comparison to the spectra of ThT. The obtained results indicate that the new synthesized dye is a useful probe for amyloid fibrils detection and study of their formation. The present work is a step towards to the creation of fluorescent dyes that can be used for immediate testing of amyloid aggregates in vivo.