Synthetic α-Helical Peptides as Potential Inhibitors of the ACE2 SARS-CoV-2 Interaction

Area of Science:

• Biochemistry
• Structural Biology
• Virology

Background:

• SARS-CoV-2 viral entry depends on spike protein binding to the ACE2 receptor's alpha1-helix.
• Alpha-helical peptides mimicking this motif offer a strategy for developing viral entry inhibitors.

Purpose of the Study:

• To design and synthesize alpha-helical peptides that inhibit SARS-CoV-2 spike protein binding to ACE2.
• To investigate the role of peptide helicity and specific sequences in binding affinity.

Main Methods:

• Utilized the ProM-5 module to induce alpha-helicity in ACE2-inspired peptide sequences.
• Synthesized N-capped peptides with varying sequences and helicities.
• Assessed peptide alpha-helicity using spectroscopic methods.
• Determined peptide binding affinities to the SARS-CoV-2 spike protein via microscale thermophoresis (MST).

Main Results:

• Peptides incorporating the ProM-5 module exhibited increased alpha-helicity, reaching up to 63%.
• Replacing non-binding amino acids with alanine further enhanced helicity.
• MST analysis revealed that alpha-helical content had a minor impact on binding affinity.
• Identified a specific Ac-βHAsp-PP-capped peptide with high binding affinity (K_D = 62 nM) to the spike protein.

Conclusions:

• Rigidified peptides can effectively mimic ACE2's alpha1-helix and inhibit SARS-CoV-2 binding.
• High helicity does not directly correlate with strong binding affinity.
• A lead peptide candidate with potent spike protein binding was identified, offering therapeutic potential.