Fig. 3.

Structural comparison of spike (S) proteins trimeric conformation. The S protein of the SARS-CoV-2, SARS-CoV, and MERS-CoV exists in homologous trimeric conformation consisting of three chains named chain A, B, and C. These chains are aligned and visualized in PyMOL which revealed a high degree of structural deviations in the N-terminal domains (NTDs) and receptor-binding domains (RBDs) of the chain A and C compared to that of chain B. The structural coordinates of the S protein of the SARS-CoV-2, SARS-CoV, and MERS-CoV were taken from the RCSB Protein Data Bank with PDB IDs: 6VSB, 6ACD, and 5W9H, respectively.