Computational and Experimental Identification of Potential Neutralizing Peptides Derived from Human ACE2 Against SARS-CoV-2 Infection

The human angiotensin-converting enzyme 2 (hACE2) is the primary receptor for the entry of SARS-CoV-2. Some human alleles of ACE2 exhibit an improved affinity for the SARS-CoV-2 Spike protein. However, the impact of ACE2 polymorphisms on SARS-CoV-2 infection remains unclear. Our previous study predicted that G431 and S514 in the receptor-binding domain (RBD) od SARS-CoV-2 S1 domain are important for S protein stability, and that S protein residues G496 and F497 and ACE2 residues D355 and Y41 are critical for the RBD–ACE2 interaction (1). In this study, we explored the potential of hACE2-derived neutralizing peptides as a therapeutic strategy against SARS-CoV-2 and investigated how ACE2 polymorphisms affect RBD–ACE2 binding affinity. We applied computational saturation mutagenesis to systematically screen the binding affinity changes among all possible ACE2 missense mutations within the ACE2–Wuhan-S1 complex. Mutations at ACE2 residues D355 and Y41 were predicted to weaken binding affinity, whereas those at N330 and D30 enhanced it. We identified six ACE2 regions (19–49, 65–102, 320–333, 348–359, 378–395, 552–563) to be vital for ACE2–RBD interaction. We synthesized peptides corresponding to these six regions and tested them using a pseudotyped viral particle system and dot blot assay. Three peptides were confirmed to bind with S protein, and four exhibited inhibitory effects. We aligned ACE2–Wuhan-S1 and ACE2–Omicron-S1 complexes, conducted correlation analysis, and observed similar binding patterns, suggesting that these peptides also have potential to neutralize Omicron strains.