title: Structural Analysis and Aggregation Propensity of Pyroglutamate Aβ(3-40) in Aqueous Trifluoroethanol.
abstract: A hallmark of Alzheimer's disease (AD) is the accumulation of extracellular amyloid-β (Aβ) plaques in the brains of patients. N-terminally truncated pyroglutamate-modified Aβ (pEAβ) has been described as a major compound of Aβ species in senile plaques. pEAβ is more resistant to degradation, shows higher toxicity and has increased aggregation propensity and β-sheet stabilization compared to non-modified Aβ. Here we characterized recombinant pEAβ(3-40) in aqueous trifluoroethanol (TFE) solution regarding its aggregation propensity and structural changes in comparison to its non-pyroglutamate-modified variant Aβ(1-40). Secondary structure analysis by circular dichroism spectroscopy suggests that pEAβ(3-40) shows an increased tendency to form β-sheet-rich structures in 20% TFE containing solutions where Aβ(1-40) forms α-helices. Aggregation kinetics of pEAβ(3-40) in the presence of 20% TFE monitored by thioflavin-T (ThT) assay showed a typical sigmoidal aggregation in contrast to Aβ(1-40), which lacks ThT positive structures under the same conditions. Transmission electron microscopy confirms that pEAβ(3-40) aggregated to large fibrils and high molecular weight aggregates in spite of the presence of the helix stabilizing co-solvent TFE. High resolution NMR spectroscopy of recombinantly produced and uniformly isotope labeled [U-15N]-pEAβ(3-40) in TFE containing solutions indicates that the pyroglutamate formation affects significantly the N-terminal region, which in turn leads to decreased monomer stability and increased aggregation propensity.
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Dammers
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.|Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Gremer
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Reiß
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Antonia N
authors.initials: AN
authors.lastname: Klein
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.|Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Neudecker
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Hartmann
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Na
authors.initials: N
authors.lastname: Sun
authors.affiliation: Fraunhofer Institute for Cell Therapy and Immunology, Department of Drug Design and Target Validation, 06120, Halle (Saale), Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Demuth
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Schwarten
authors.affiliation: Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425, Jülich, Germany.|Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Willbold
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D017433:Protein Structure, Secondary; D011761:Pyrrolidonecarboxylic Acid / Q000737:chemistry*; D014270:Trifluoroethanol / Q000737:chemistry*
chemical_list: D016229:Amyloid beta-Peptides; D014270:Trifluoroethanol; D011761:Pyrrolidonecarboxylic Acid