Differences in potential binding interactions were found between ACE2 domain and RBD domain of SARS-CoV-2 and RaTG13 S trimers. SARS-CoV-2 has Phe486 interacting with ACE2 human receptor while the bat virus has Leu486 instead, which is less bulky. SARS-CoV-2 also has a Gln493 that is able to form a hydrogen bond of Glu35 in ACE2, while RaTG13 has a tyrosine that is unlikely to bond with Glu35. More differences are shown in Fig 3b and Fig 3c. These distinctions may impact the differences in S glycoprotein affinity to ACE2 between SARS-CoV-2 and RaTG13.