Computational simulations reveal the binding dynamics between human ACE2 and the receptor binding domain of SARS-CoV-2 spike protein

Cecylia S. Lupala; Xuanxuan Li; Jian Lei; Hong Chen; Jianxun Qi; Haiguang Liu; Xiao-dong Su

the key residues at the binding interface were identified and summarized in Table 2 for the three representative models (see Figure 2 ). Majority of these residues are conserved for these three models, except that the model#1 (Figure 2a ) has additional contacts to the ACE2 from residues in the L 67 region (highlighted with green color in Table 2 ). As shown in Figure 2 , the L 67 remained in the starting position for the other two representative models (Figure 2b,c) . The same simulations were carried out for the SARS-RBD/ACE2 complex, serving as a comparative system. Interestingly, the SARS-RBD counterpart of the L 67 in CoV2-RBD did not form close contacts with the ACE2 in three simulations. It is worthwhile to mention that the sequence identity between CoV2-RBD and SARS-RBD is low in this loop region, suggesting the loop region might be partially responsible for the difference in the receptor binding.