[4S03m] 08. Functional Molecules and Materials for Biological Systems - Part 4

10:40 AM - 11:10 AM JST(1:40 AM - 2:10 AM UTC)

[4FMBS-02-KL] Peptide stereocomplexation as a novel strategy for sequence-selective targeting of an intrinsically disordered protein

○Tatsuo Maruyama¹, Kenta Morita¹, Kunihisa Sugimoto² (1. Kobe University (Japan), 2. Kindai University (Japan))

Keywords:

stereocomplex,peptide,intrinsically disordered protein,self-assembly,chirality

Stereocomplexation between enantiomeric polymers is a well-known phenomenon that can enhance the structural stability of supramolecular assemblies. However, the sequence requirements for stereocomplex formation in short peptides are still not well understood. In this study, we systematically investigated stereocomplexation between complementary L- and D-peptides using simple tripeptide models and explored its potential application for targeting intrinsically disordered proteins (IDPs). Tripeptides composed of phenylalanine and lysine residues were designed to examine the roles of hydrophobic, π-π, and electrostatic interactions in heterochiral peptide association. Aggregation assays revealed that the L/D pair Ac-FFK/Ac-ffk formed stable aggregates in aqueous solution, whereas other sequence combinations such as Ac-FKF/Ac-fkf and Ac-KFF/Ac-kff did not. Single-crystal X-ray diffraction analysis demonstrated that Ac-FFK/Ac-ffk formed racemic crystals with alternating L- and D-peptides arranged in parallel β-sheet structures. Structural analysis indicated that stereocomplex formation was driven by a combination of hydrophobic interactions between phenylalanine residues and electrostatic interactions involving lysine and the C-terminal carboxylate group. Thermodynamic and dynamic analyses further supported this mechanism. Isothermal titration calorimetry showed that the interaction was predominantly entropy-driven, suggesting a major contribution from hydrophobic interactions. Molecular dynamics simulations indicated that heterochiral peptide pairs can approach each other more closely than homochiral pairs due to reduced steric hindrance. Fluorescence resonance energy transfer experiments also confirmed direct association between L- and D-peptides in solution. Based on these insights, we rationally designed a D-peptide capable of interacting with the –FFAE– motif of amyloid-β42 (Aβ42), a disease-related IDP involved in Alzheimer’s disease. The designed D-peptide, Ac-fffakr₅-NH₂, significantly suppressed Aβ42 fibrillization and reduced its cytotoxicity in neuronal-like cells. These findings establish peptide stereocomplexation as a promising molecular recognition strategy and demonstrate its potential for designing sequence-targeting ligands against intrinsically disordered proteins.