A β-sheet-binding scaffold was equipped with long-range chemical groups for tertiary contacts toward specific regions of the Alzheimer's Aβ fibril. The new constructs contain a trimeric aminopyrazole carboxylic acid, elongated with a C-terminal binding site, whose influence on the aggregation behavior of the Aβ(42) peptide was studied. MD simulations after trimer docking to the anchor point (F19/F20) suggest distinct groups of complex structures each of which featured additional specific interactions with characteristic Aβ regions. Members of each group also displayed a characteristic pattern in their antiaggregational behavior toward Aβ. Specifically, remote lipophilic moieties such as a dodecyl, cyclohexyl, or LPFFD fragment can form dispersive interactions with the nonpolar cluster of amino acids between I31 and V36. They were shown to strongly reduce Thioflavine T (ThT) fluorescence and protect cells from Aβ lesions (MTT viability assays). Surprisingly, very thick fibrils and a high β-sheet content were detected in transmission electron microscopy (TEM) and CD spectroscopic experiments. On the other hand, distant single or multiple lysines which interact with the ladder of stacked E22 residues found in Aβ fibrils completely dissolve existing β-sheets (ThT, CD) and lead to unstructured, nontoxic material (TEM, MTT). Finally, the triethyleneglycol spacer between heterocyclic β-sheet ligand and appendix was found to play an active role in destabilizing the turn of the U-shaped protofilament. Fluorescence correlation spectroscopy (FCS) and sedimentation velocity analysis (SVA) provided experimental evidence for some smaller benign aggregates of very thin, delicate structure (TEM, MTT). A detailed investigation by dynamic light scattering (DLS) and other methods proved that none of the new ligands acts as a colloid. The evolving picture for the disaggregation mechanism by these new hybrid ligands implies transformation of well-ordered fibrils into less structured aggregates with a high molecular weight. In the few cases where fibrillar components remain, these display a significantly altered morphology and have lost their acute cellular toxicity.
More than the sum of its parts: Novel hybrid compounds consisting of an organic β‐sheet‐breaking moiety and a signaling, D‐enantiomeric Aβ‐recognizing peptide moiety have been designed (see picture). The compounds, which were chemically synthesized and characterized by several techniques, combine rational design and drug selection from libraries and inhibit Aβ oligomerization and Aβ‐induced synaptic pathology.
[2] Rational entworfene, kleine organische Moleküle, die an b-Faltblattstrukturen binden und diese auflösen (b-Faltblattbrecher, "b-sheet breaker"), sind in zellfreien In-vitro-Systemen sehr effizient, waren aber wegen ihrer stark unspezifischen Bindung bislang in vivo nicht sehr wirkungsvoll.Unsere Überlegung war daher, die Wirksamkeit kleiner organischer b-Faltblattbrecher durch Hinzufügen einer molekularen Erkennungsdomäne zu verbessern, den b-Faltblattbrecher also als Bestandteil einer neuen Hybridsubstanz zum Zielmolekül zu lotsen. Molekulare Erkennung ist eine Grundeigenschaft von Polypeptiden, die durch die Verwendung von evolutionären Algorithmen (z. B. Phagen-Display) iterativ identifiziert und optimiert werden kann. Auf diese Weise fanden wir in einem Spiegelbild-Phagen-Display [3,4] das D3-Peptid, ein d-enantiomeres Dodecapeptid, das über seine spezifische Wechselwirkung die Ab-Aggregation, Plaquebildung und neuroinflammatorische Prozesse in Hirnen von transgenen (APPswe/PSDE9)-Mäusen modulieren kann. [3,5] In unserer Hybridsubstanz (Abbildung 1) würden wir somit zwei völlig unterschiedliche Strategien der Substanzentwicklung miteinander vereinen: einerseits die evolutionär geleitete Selektion aus Bibliotheken und andererseits die Verwendung rational entworfener niedermolekularer organischer Substanzen. Als b-Faltblattbrecher wählten wir die Aminopyrazole, die eine spezifische Donor-Akzeptor-Donor-
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.