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)
Artikel i vetenskaplig tidskrift, 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 dye

Alzheimer's disease

Thioflavin-T

Amyloid fibrils

Amyloid-B

Fluorescence lifetime

Författare

David Lindberg

Chalmers, Biologi och bioteknik, Kemisk biologi

Moa Sandberg Wranne

Kemi och kemiteknik, Kemi och biokemi, Fysikalisk kemi

Melina Gilbert Gatty

Kemi och kemiteknik, Kemi och biokemi, Fysikalisk kemi

Fredrik Westerlund

Chalmers, Biologi och bioteknik, Kemisk biologi

Elin Esbjörner Winters

Chalmers, Biologi och bioteknik, Kemisk biologi

Biochemical and Biophysical Research Communications

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

Vol. 458 418-423

Styrkeområden

Nanovetenskap och nanoteknik

Livsvetenskaper och teknik

Ämneskategorier

Fysikalisk kemi

DOI

10.1016/j.bbrc.2015.01.132