Engineering the Bioactive Profile of Medicinal Peptides by Multiarm Polyethylene Glycol Conjugation

PEGylation plays a crucial role in peptide modification and has been widely applied in the field of biomedicine, demonstrating significant potential for enhancing peptide drug performance. Herein, we synthesized melittin peptides modified with single arm, double arm, and four arm of PEG12, utilizing lysine side chains as branching points, to systematically investigate the effects of multiarm PEGylation on toxicity, hemolytic activity, stability, and membrane-disrupting ability. Our results revealed that increasing the number of PEG arms significantly reduced the cytotoxicity and hemolytic activity of melittin (with IC₅₀ increasing approximately 20-fold) while simultaneously enhancing serum stability. These effects were attributed to the improved water solubility and altered hydrophilicity/hydrophobicity balance at the N-terminus, which modulated the interactions with cell membranes and reduced the membrane penetration capacity. Meanwhile, the steric hindrance effect that was caused by multiarm PEG modification prevented the destruction of cell membranes by melittin. The strategy of terminal PEGylation was expected to minimize systemic toxicity and in vivo degradation. Collectively, our findings highlight the critical role of the topological structure PEG in fine-tuning peptide drug performance, providing valuable insights for the design of safer and more effective peptide-based therapeutics.