Fig. 1.

Schematic representation of the contact zone between SARS-CoV-2 spike receptor-binding domain (orange) and ACE2 (green). Disulfide bridges critical for binding affinity are present at position C480–C488 and C344–C361 (shown on the left); their reduction at the protein-protein interface is proposed to produce conformational changes that decrease binding affinity [17,18]. The figure was drawn using PDB entry 6M0J. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)