THIOFLAVIN T INTERACTION WITH AMYLOID FIBRILS AS AN INSTRUMENT FOR THEIR STUDYING
A. I. Sulatskaya,1, 2, * I. M. Kuznetsova 1
1 Institute of Cytology RAS, St. Petersburg,
and 2 St. Petersburg State Polytechnical University;
* e-mail: ansul@mail.ru
Benzthiazole dye thioflavin T (ThT) is widely used to study the formation and structure of amyloid fibrils.
Nevertheless, till now there is no common opinion concerning molecular mechanisms of ThT binding to amyloid
fibrils and the reasons of dramatic increase in its fluorescence quantum yield on incorporation into amyloid
fibrils. Our data prove that ThT molecules incorporate in the amyloid fibrils in the monomeric form and there is
no ground to suppose the formation of ThT dimers, eximers, or micells. It was shown that the increase in the quantum
yield of ThT incorporated in amyloid fibrils was caused by restriction of benzthiazole and aminobenzene
rings torsion fluctuations relative to each other. The use of equilibrium microdialysis allowed determining the
absorption spectrum, the number of binding modes of ThT with insulin amyloid fibrils and for each mode determining
the binding constants and the number of binding sites for each mode.
Key words: thioflavin T, amyloid fibrils, quantum yield, absorption, fluorescence, insulin
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