Steady-state and time-resolved Thioflavin-T fluorescence can report on morphological differences in amyloid fibrils formed by A beta(1-40) and A beta(1-42)
Journal article, 2015

Thioflavin-T (ThT) is one of the most commonly used dyes for amyloid detection, but the origin of its fluorescence enhancement is not fully understood. Herein we have characterised the ThT fluorescence response upon binding to the A beta(1-40) and A beta(1-42) variants of the Alzheimer's-related peptide amyloid-beta, in order to explore how the photophysical properties of this dye relates to structural and morphological properties of two amyloid fibril types formed by peptides with a high degree of sequence homology. We show that the steady-state ThT fluorescence is 1.7 times more intense with A beta(1-40) compared to A beta(1-42) fibrils in concentration matched samples prepared under quiescent conditions. By measuring the excited state lifetime of bound ThT, we also demonstrate a distinct difference between the two fibril isoforms, with A beta(1-42) fibrils producing a longer ThT fluorescence lifetime compared to A beta(140). The substantial steady-state intensity difference is therefore not explained by differences in fluorescence quantum yield. Further, we find that the ThT fluorescence intensity, but not the fluorescence lifetime, is dependent on the fibril preparation method (quiescent versus agitated conditions). We therefore propose that the fluorescence lifetime is inherent to each isoform and sensitively reports on fibril microstructure in the protofilament whereas the total fluorescence intensity relates to the amount of exposed beta-sheet in the mature A beta fibrils and hence to differences in their morphology. Our results highlight the complexity of ThT fluorescence, and demonstrate its extended use in amyloid fibril characterisation.

Amyloid-B

Thioflavin-T

Amyloid dye

Amyloid fibrils

Alzheimer's disease

Fluorescence lifetime

Author

David Lindberg

Chalmers, Biology and Biological Engineering, Chemical Biology

Moa Sandberg Wranne

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Melina Gilbert Gatty

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Fredrik Westerlund

Chalmers, Biology and Biological Engineering, Chemical Biology

Elin Esbjörner Winters

Chalmers, Biology and Biological Engineering, Chemical Biology

Biochemical and Biophysical Research Communications

0006-291X (ISSN) 1090-2104 (eISSN)

Vol. 458 2 418-423

Areas of Advance

Nanoscience and Nanotechnology

Life Science Engineering (2010-2018)

Subject Categories

Physical Chemistry

DOI

10.1016/j.bbrc.2015.01.132

More information

Latest update

2/16/2022