title: Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates.
abstract: BACKGROUND
  Special diphenyl-pyrazole compounds and in particular anle138b were found to reduce the progression of prion and Parkinson's disease in animal models. The therapeutic impact of these compounds was attributed to the modulation of α-synuclein and prion-protein aggregation related to these diseases.
  
  
  METHODS
  Photophysical and photochemical properties of the diphenyl-pyrazole compounds anle138b, anle186b and sery313b and their interaction with monomeric and aggregated α-synuclein were studied by fluorescence techniques.
  
  
  RESULTS
  The fluorescence emission of diphenyl-pyrazole is strongly increased upon incubation with α-synuclein fibrils, while no change in fluorescence emission is found when brought in contact with monomeric α-synuclein. This points to a distinct interaction between diphenyl-pyrazole and the fibrillar structure with a high binding affinity (Kd=190±120nM) for anle138b. Several α-synuclein proteins form a hydrophobic binding pocket for the diphenyl-pyrazole compound. A UV-induced dehalogenation reaction was observed for anle138b which is modulated by the hydrophobic environment of the fibrils.
  
  
  CONCLUSIONS
  Fluorescence of the investigated diphenyl-pyrazole compounds strongly increases upon binding to fibrillar α-synuclein structures. Binding at high affinity occurs to hydrophobic pockets in the fibrils.
  
  
  CONCLUSIONS
  The observed particular fluorescence properties of the diphenyl-pyrazole molecules open new possibilities for the investigation of the mode of action of these compounds in neurodegenerative diseases. The high binding affinity to aggregates and the strong increase in fluorescence upon binding make the compounds promising fluorescence markers for the analysis of aggregation-dependent epitopes.
authors.affiliation: BioMolekulare Optik and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany.
authors.forename: Andreas A
authors.initials: AA
authors.lastname: Deeg
authors.affiliation: BioMolekulare Optik and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Reiner
authors.affiliation: Zentrum für Neuropathologie und Prionforschung, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 23, 81377 Munich, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Schmidt
authors.affiliation: BioMolekulare Optik and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schueder
authors.affiliation: NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
authors.forename: Sergey
authors.initials: S
authors.lastname: Ryazanov
authors.affiliation: Zentrum für Neuropathologie und Prionforschung, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 23, 81377 Munich, Germany.
authors.forename: Viktoria C
authors.initials: VC
authors.lastname: Ruf
authors.affiliation: NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Giller
authors.affiliation: NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Becker
authors.affiliation: NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
authors.forename: Andrei
authors.initials: A
authors.lastname: Leonov
authors.affiliation: NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; DFG Research Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Griesinger
authors.affiliation: Zentrum für Neuropathologie und Prionforschung, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 23, 81377 Munich, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Giese
authors.affiliation: BioMolekulare Optik and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany. Electronic address: wolfgang.zinth@physik.uni-muenchen.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zinth
mesh_terms: D052117:Benzodioxoles / Q000737:chemistry*; D066329:Protein Aggregates; D011485:Protein Binding; D011720:Pyrazoles / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D051844:alpha-Synuclein / Q000737:chemistry*
chemical_list: C000593290:3-(1,3-benzodioxol-5-yl)-5-(3-bromophenyl)-1H-pyrazole; D052117:Benzodioxoles; D066329:Protein Aggregates; D011720:Pyrazoles; D051844:alpha-Synuclein
keywords: Amyloid dye; Anle138b; Fluorescence marker; Parkinson's disease; Protein aggregation; α-Synuclein