title: Studies of interaction between cyanine dye T-284 and fibrillar alpha-synuclein.
abstract: A key feature of Parkinson's disease is the formation and accumulation of amyloid fibrils of the natively unfolded protein α-synuclein (ASN) inside neurons. Recently we have proposed novel sensitive monomethinecyanine dye T-284 as fluorescent probe for quantitative detection of ASN amyloid fibrils. In this study the T-284 dye complex with ASN fibril was characterized by means of fluorescence anisotropy, atomic force microscopy and time-resolved fluorescence techniques to give further insights into the mode of dye interaction with amyloid fibrils. The fluorescence anisotropy of T-284 was shown to noticeably increase upon addition of aggregated proteins indicating on stable dye/amyloid fibril complex formation. AFM imaging of fibrillar wild-type ASN revealed differences in heights between ASN fibrils alone and in presence of the T-284 dye (6.37 ± 1.0 nm and 8.0 ± 1.1 nm respectively), that is believed to be caused by embedding of T-284 dye molecules in the "binding channel" running along the fibril. Fluorescence decay analysis of the T-284 in complexes with fibrillar ASN variants revealed the fluorescence lifetime values for T-284/fibril complexes to be an order of magnitude higher as compared to the free dye. Also, the fluorescence decay of free T-284 was bi-exponential, while dye bound to protein yields tri-exponential decay. We suppose that in complexes with fibrillar ASN variants T-284 dye might exist in different "populations" due to interaction with fibrils in different conformers and ways. The exact binding mode of T-284 with ASN fibrils needs further studies. Studied parameters of dye/amyloid fibril complexes are important for the characterization and screening of newly-developed amyloid-sensitive dyes.
authors.affiliation: Department of Combinatorial Chemistry, Institute of Molecular Biology and Genetics of the National Academy of Sciences of Ukraine, 150 Zabolotnogo St., 03143, Kyiv, Ukraine.
authors.forename: Kateryna D
authors.initials: KD
authors.lastname: Volkova
authors.forename: Vladyslava B
authors.initials: VB
authors.lastname: Kovalska
authors.forename: Mykhaylo
authors.initials: M
authors.lastname: Yu Losytskyy
authors.forename: Gertjan
authors.initials: G
authors.lastname: Veldhuis
authors.forename: G M J
authors.initials: GM
authors.lastname: Segers-Nolten
authors.forename: Olexiy I
authors.initials: OI
authors.lastname: Tolmachev
authors.forename: Vinod
authors.initials: V
authors.lastname: Subramaniam
authors.forename: Sergiy M
authors.initials: SM
authors.lastname: Yarmoluk
mesh_terms: D002232:Carbocyanines / Q000737:chemistry*; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D051844:alpha-Synuclein / Q000737:chemistry*
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; C556877:T-284 dye; D051844:alpha-Synuclein