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Binding of Thioflavin‑T to Amyloid Fibrils Leads to Fluorescence Self-Quenching and Fibril Compaction

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journal contribution
posted on 12.04.2017, 00:00 by David J. Lindberg, Anna Wenger, Elin Sundin, Emelie Wesén, Fredrik Westerlund, Elin K. Esbjörner
Thioflavin-T binds to and detects amyloid fibrils via fluorescence enhancement. Using a combination of linear dichroism and fluorescence spectroscopies, we report that the relation between the emission intensity and binding of thioflavin-T to insulin fibrils is nonlinear and discuss this in relation to its use in kinetic assays. We demonstrate, from fluorescence lifetime recordings, that the nonlinearity is due to thioflavin-T being sensitive to self-quenching. In addition, thioflavin-T can induce fibril compaction but not alter fibril structure. Our work underscores the photophysical complexity of thioflavin-T and the necessity of calibrating the linear range of its emission response for quantitative in vitro studies.