Electrostatic potential map of 2019-nCoV RBD (left panel), and SARS-CoV RBD (right panel). The position of K417 in the 2019-nCoV RBD is indicated by black arrow. The N-terminal helix of ACE2 is shown as green ribbon. The PDB code for SARS-CoV RBD/ACE2 complex: 2AJF. 