Designed Macrocyclic Peptides as Nanomolar Amyloid Inhibitors Based on Minimal Recognition Elements

Abstract

Amyloid self-assembly is linked to the pathogenesis of Alzheimer's disease (AD) and type 2 diabetes (T2D), but so far, no anti-amyloid compound has reached the clinic. Macrocyclic peptides belong to the most attractive drug candidates. Herein we present macrocyclic peptides (MCIPs) designed using minimal IAPP-derived recognition elements as a novel class of nanomolar amyloid inhibitors of both Aβ40(42) and IAPP or Aβ40(42) alone and show that chirality controls inhibitor selectivity. Sequence optimization led to the discovery of an Aβ40(42)-selective MCIP exhibiting high proteolytic stability in human plasma and human blood-brain barrier (BBB) crossing ability in a cell model, two highly desirable properties for anti-amyloid AD drugs. Owing to their favorable properties, MCIPs should serve as leads for macrocyclic peptide-based anti-amyloid drugs and scaffolds for the design of small-molecule peptidomimetics for targeting amyloidogenesis in AD or in both AD and T2D.

Peptide‐Based Molecular Strategies To Interfere with Protein Misfolding, Aggregation, and Cell Degeneration

“…b) Design concept, inhibitory effects, and suggested mechanism of the inhibitor function of ISMs . c) Minimalistic design concept, sequences, and functions of the MCIPs …”

Structural Insight into IAPP‐Derived Amyloid Inhibitors and Their Mechanism of Action

“…Thecorrect spatial arrangement of side chains allows them to efficiently capture Ab40 and direct it into off-pathway non-toxic aggregates. [24] Figure 7s chematically illustrates different amyloid selfassembly inhibition mechanisms involving classical single-site binding,t ogether with intervention strategies that employ colloid formation or the here suggested ISM-induced LLPSlike process.S ingle-site binding events are the classical paradigm for ad rug-enzyme complex. Because of the low affinity and the lack of deep binding pockets,t his class of inhibitors is not very effective for amyloids (Figure 7, top).…”

“…Thedesign of the ISMs was based on the finding that amyloids are generally composed of a b-sheet-turn-b-sheet structural motif and that IAPP uses the same two binding regions for both its amyloid self-and its cross-amyloid hetero-assembly with Ab40/42. [1a, 2] ISMs were thus derived by linking the two hot segments IAPP (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) and IAPP (22)(23)(24)(25)(26)(27)(28) in native or N-methylated form to each other via different linkers,mostly tripeptide sequences consisting of identical amino acids;notably,these two segments are highly homologous to segments of the amyloid core of Ab. [3] High Ab40/42 anti-amyloidogenic activity was found for seven out of the 16 studied ISMs with six of them containing bulky hydrophobic/aromatic residues (e.g.L LL, III, FFF) in the linker tripeptide and one of them, termed R3-GI, the RRR tripeptide.…”

Peptid‐basierte molekulare Strategien zum Einsatz bei Proteinfehlfaltung, Proteinaggregation und Zelldegeneration

“…[41] Diese so genannten "Macrocyclic Inhibitory Peptides" (MCIPs) ahmen funktionelle (inhibitorische) IAPP-Interaktionsflächen nach, während sie zugleich minimale IAPP-basierte Erkennungselemente beibehalten (Abbildung 7 c). [41,47] [6,49] Auf der Suche nach Strategien zur Reduktion der nicht-nativen Aggregation von Insulin, die zu Komplikationen bei seiner biomedizinischen Anwendbarkeit führt, identifizierten wir IAPP-GI als einen nanomolaren Inhibitor. [11d] Erwartungsgemäß interferiert die IAPP-GI-Insulin-Wechselwirkung nicht mit der Insulinfunktion, da IAPP-GI ein Analog des nativ vorkommenden Insulin-Interaktionspartners IAPP ist.…”