title: High Fluorescence Anisotropy of Thioflavin T in Aqueous Solution Resulting from Its Molecular Rotor Nature.
abstract: Thioflavin T (ThT) is widely used to study amyloid fibrils while its properties are still debated in the literature. By steady-state and femtosecond time-resolved fluorescence we showed that, unlike small sized rigid molecules, the fluorescence anisotropy value of the free ThT in aqueous solutions is very high, close to the limiting value. This is determined by the molecular rotor nature of ThT, where the direction of the ThT transition dipole moment S₀ → S₁* is not changed either by the internal rotation of the ThT benzothiazole and aminobenzene rings relative to each other in the excited state, because the axis of this rotation coincides with the direction of the transition dipole moment, or by the rotation of the ThT molecule as a whole, because the rate of this process is 3 orders of magnitude smaller than the rate of the internal rotation which leads to the fluorescence quenching. Consequently, ThT fluorescence anisotropy cannot be directly used to study amyloid fibrils formation, as it was proposed by some authors.
authors.affiliation: Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology of the Russian Academy of Sciences , St. Petersburg 194064, Russia.
authors.forename: Irina M
authors.initials: IM
authors.lastname: Kuznetsova
authors.affiliation: Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology of the Russian Academy of Sciences , St. Petersburg 194064, Russia.
authors.forename: Anna I
authors.initials: AI
authors.lastname: Sulatskaya
authors.affiliation: Department of Physics, Yanka Kupala Grodno State University , Grodno 230023, Belarus.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Maskevich
authors.affiliation: Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology of the Russian Academy of Sciences , St. Petersburg 194064, Russia.|Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida , 12901 Bruce B. Downs Boulevard, MDC07, Tampa, Florida 33612, United States.
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Uversky
authors.affiliation: Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology of the Russian Academy of Sciences , St. Petersburg 194064, Russia.|Department of Biophysics, Peter the Great St. Petersburg Polytechnic University , St. Petersburg 195251, Russia.
authors.forename: Konstantin K
authors.initials: KK
authors.lastname: Turoverov
mesh_terms: D016880:Anisotropy; D052160:Benzothiazoles; D005453:Fluorescence; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013844:Thiazoles / Q000032:analysis* / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D052160:Benzothiazoles; D012996:Solutions; D013844:Thiazoles; D014867:Water; C009462:thioflavin T