Table 2.

Human ACE2 receptor (hACE2) quartets and their interaction energies [kcal/mol]${}^{\mathrm{a}}$with neighboring${}^{\mathrm{b}}$ S-RBD residues.

Quartet	Human ACE2 Receptor
	Residues	${\text{E}}_{\text{Int}}^{\text{DFT}}$	${\text{E}}_{\text{Int}}^{\text{DD}}$	${\text{E}}_{\text{Int}}^{\text{Total}}$
AQ1	ASP30-LYS31-ASN33-HIS34	$+$17.50	$-$13.10	$+$4.41
AQ2	GLN24-ALA25-LYS26-THR27	$+$51.12	$-$7.32	$+$43.80
AQ3	GLU329-ASN330-LYS353-GLY354	$-$30.82	$-$28.81	$-$59.63
AQ4	GLU37-ASP38-TYR41-GLN42	$-$38.48	$-$16.30	$-$54.78
AQ5	LEU91-THR92-GLN325-GLY326	$+$11.82	$-$2.25	$+$9.57
AQ6	MET82-TYR83-GLN89-ASN90	$+$34.46	$-$5.23	$+$29.23
AQ7	SER44-LEU45-ALA46-SER47	$+$28.01	$-$2.60	$+$25.41
AQ8	SER77-THR78-LEU79-ALA80	$+$26.03	$-$2.01	$+$24.02

^aDFT energies computed at 6-311+G(d,p)/B3LYP level; Dispersion (DD) corrections evaluated with semiempirical method²⁷.

^bAll S-RBD residues within 4.5 $\mathrm{\AA }$ of each ACE2 quartet were included.