Revisiting thioflavin T (ThT) fluorescence as a marker of protein fibrillation - The prominent role of electrostatic interactions.

Elad Arad, Hodaya Green, Raz Jelinek, Hanna Rapaport

Journal of colloid and interface science 2020 Aug 01

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Thioflavin T (ThT), a benzothiazole-based fluorophore, is a prominent dye widely employed for monitoring amyloid fibril assembly. Despite the near-universal presumption that ThT binds to β-sheet domains upon fibrillar surface via hydrophobic forces, the contribution of the positive charge of ThT to fibril binding and concomitant fluorescence enhancement have not been thoroughly assessed. Here we demonstrate a considerable interdependence between ThT fluorescence and electrostatic charges of peptide fibrils. Specifically, by analyzing both fibril-forming synthetic peptides and prominent natural fibrillar peptides, we demonstrate pronounced modulations of ThT fluorescence signal that were solely dependent upon electrostatic interactions between ThT and peptide surface. The results further attest to the fact that fibril ζ-potential rather than pH-dependent assembly of the fibrils constitute the primary factor affecting ThT binding and fluorescence. This study provides the first quantitative assessment of electrostatically driven ThT fluorescence upon adsorption to amyloid fibrils. Copyright © 2020 Elsevier Inc. All rights reserved.

Citation

Elad Arad, Hodaya Green, Raz Jelinek, Hanna Rapaport. Revisiting thioflavin T (ThT) fluorescence as a marker of protein fibrillation - The prominent role of electrostatic interactions. Journal of colloid and interface science. 2020 Aug 01;573:87-95