Improving the Stability and Anti-Infective Activity of Sea Turtle AMPs Using Multiple Structural Modification Strategies

Abstract

Antimicrobial peptides (AMPs) are regarded as promising candidates for combating antimicrobial resistance. Previously we identified an AMP named Cm-CATH2 from the green sea turtle, which exhibited potent antibacterial activity and attractive potential in application. However, natural AMPs including Cm-CATH2 frequently suffer from structural instability and sensitivity to physiological conditions, limiting their effectiveness. Herein, we explored various strategies to enhance the efficacy and stability of Cm-CATH2, including peptide truncation, non-natural amino acid substitutions, disulfide bond-based cyclization, and stapled peptide techniques. The results demonstrated that the truncated NCM4 significantly improved the antimicrobial capability of Cm-CATH2 while also enhancing its anti-inflammatory and antibiofilm activities with minimal cytotoxicity. Further ornithine-substituted peptide oNCM markedly enhanced the stability of NCM4 without compromising its antimicrobial efficacy. This study successfully designed a lead peptide oNCM with significant development potential, while providing valuable insights into the advantages and limitations associated with diverse strategies for enhancing the stability of AMPs.