Resilin-Mimetic Copolypeptides from Minimal Motifs: A Chemoenzymatic and Bioinspired Circular Design for Sustainable Bioelastic Materials

Resilin, an elastic protein found in insect cuticles, is exceptionally resilient because of its amino acid sequence and dityrosine cross-linking. In this study, the chemoenzymatic synthesis of resilin-mimetic polypeptides based on minimal peptide motifs incorporating glycine, proline, serine, and tyrosine residues is reported. Using papain-catalyzed copolymerization of tripeptide motifs (GPG: glycine-proline-glycine and SYS: serine-tyrosine-serine) and subsequent dityrosine cross-linking with horseradish peroxidase, we synthesized polypeptides mimicking key structural features of resilin. SYS-rich and GPG-rich copolypeptides were selectively separated from the polymerization mixture based on solubility. Structural analyses revealed that the SYS-rich copolypeptides adopted β-sheet-rich conformations and exhibited low solubility, whereas the GPG-rich copolypeptides were disordered and highly soluble. Despite their lower molecular weight, the GPG-rich copolypeptides formed stable dityrosine cross-linked networks under aqueous conditions, as confirmed by spectroscopic and rheological measurements. These findings demonstrate that short, bioinspired peptide motifs can construct simplified yet structurally relevant resilin-mimetic materials.