Intermolecular Interaction Analyses on SARS-CoV-2 Receptor Binding Domain and Human Angiotensin-Converting Enzyme 2 Receptor-Blocking Antibody/peptide Using Fragment Molecular Orbital Calculation

02 March 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The spike glycoprotein (S-protein) mediates SARS-CoV-2 entry via intermolecular interaction with human angiotensin-converting enzyme 2 (hACE2). The receptor-binding domain (RBD) of the S-protein has been considered critical for this interaction and acts as the target of numerous neutralizing antibodies and antiviral peptides. This study used the fragment molecular orbital (FMO) method to analyze the interactions between RBD and antibodies/peptides and extracted crucial residues that can be used to epitopes. The interactions evaluated as inter-fragment interaction energy (IFIE) values between the RBD and 12 antibodies/peptides showed a fairly good correlation with the experimental activity pIC50 (R2 = 0.540). Nine residues (T415, K417, Y421, F456, A475, F486, N487, N501, and Y505) were confirmed as crucial. Pair interaction energy decomposition analyses (PIEDA) showed that hydrogen bonds, electrostatic interactions, and π-orbital interactions are important. Our results provide essential information for understanding SARS-CoV-2-antibodies/peptide binding and may play roles in future antibody/antiviral drug design.


Fragment Molecular Orbital Study
Spike proteins
receptor binding domain (RBD)
Molecular Interaction energy

Supplementary materials

JPCL SI 20210226 KW


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