ИСТИНА

Nowadays, there is an active development of optical methods for the detection of various social diseases. The term amyloidosis refers to a group of diseases which are caused by the misfolding of proteins that leads to the formation of the insoluble protein aggregates, that can accumulate in certain tissues and organs. These accumulations of compact plaques are called amyloid fibrils that are highly organized, stable β-sheet-rich structures. One of the most common markers for the detection of amyloid fibrils is the Thioflavin T that selectively incorporates into fibrillar structures. According to FTIR spectroscopy, the secondary structure of albumin, which is the main transport protein in blood plasma, also contains β-sheets in its native form. Recently it was shown that Thioflavin T can bind with albumin in its native form [REF] and in spite of the fact that the equilibrium constant Ka for the fibril-Thioflavin T system is significantly higher than Ka for albumin-Thioflavin T system, the signal from protein can seriously influence on the fibril detection process. In this work we investigated experimentally the interaction between BSA and Thioflavin T in aqueous solution using as steady state so time-resolved fluorescence to determine Ka for this system. As a part of this work was also carried out the experiment for the investigation of Thioflavin T binding modes with albumin by gel filtration chromatography. This method gives us a possibility to explain in which protein structures fluorescent dye can embedded. Size-exclusion chromatography (SEC) also allowed us to determine Thioflavin T equilibrium constants with monomeric and dimeric protein forms. These investigations were also confirmed by small angle x-ray scattering (SAXS). This research was supported by the Russian Foundation for Basic Research (project 16-32-60168) and the Russian Science Foundation (project 14-15-00602). [1]Sen, Priyankar, et al. "Interactions of thioflavin T with serum albumins: spectroscopic analyses." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 74.1 (2009): 94-99.