Enzymatic Post-Modification Modulates Hierarchical Structure and Dynamics in Self-Assembled Peptide Fibers

Abstract Supramolecular peptide fibers formed by self-assembly of peptide amphiphiles (PAs) provide versatile scaffolds for constructing filamentous biomaterials, yet controlling their molecular organization and dynamic behavior after assembly remains a major challenge. Here, we report an enzymatic post-modification strategy to modulate both hierarchical structure and dynamics in PA fibers. Using Sortase A (SrtA)-mediated reactions, proteins or small-molecules were covalently introduced onto preformed PA fibers under mild aqueous conditions. Although both covalent conjugation and noncovalent adsorption of green fluorescent protein (GFP) induced similar macroscopic fiber bundling, fluorescence anisotropy and fluorescence recovery after photobleaching analyses revealed fundamentally different nanoscale organization and dynamic states. Covalently immobilized GFP formed densely clustered, proximity-stabilized arrangements on bundled fibers, whereas physically adsorbed GFP remained more dynamic and diffusive. By contrast, covalent modification with a small-molecule fluorophore converted the fibers into a rigid, static state. Importantly, sequential enzymatic modification enabled stepwise tuning of fiber dynamics without altering overall morphology. These findings demonstrate that post-assembly surface chemistry acts as an active regulator of supramolecular dynamics and highlight enzymatic functionalization as a promising approach for programming structure−dynamics relationships in adaptive peptide-based materials.