Table 2.

Comparison of hACE2 Binding to SARS-CoV-2-CTD and SARS-RBD

hACE2	SARS-CoV-2-CTD	SARS-RBD
S19 (7/1)	A475 (3,1), G476 (4)	P462 (1)
Q24 (24/6)	A475 (4), G476 (5), N487 (15, 1)	N473 (6, 1)
T27 (15/8)	F456 (5), Y473 (1), A475 (2), Y489 (7)	L443 (3), Y475 (5)
F28 (7/7)	Y489 (7)	Y475 (7)
D30 (10/2)	K417 (4, 1), L455 (2), F456 (4)	Y442 (2)
K31 (19/12)	L455 (2), F456 (5), E484 (1), Y489 (6), F490 (2), Q493 (3)	Y442 (6), Y475 (6)
H34 (20/10)	Y453 (5, 1), L455 (9), Q493 (6)	Y440 (5, 1), Y442 (1), N479 (4)
E35 (8/0)	Q493 (8)	–
E37 (7/4)	Y505 (7)	Y491 (4)
D38 (15/11)	Y449 (9, 1), G496 (5), Q498 (1)	Y436 (9, 2), G482 (1), Y484 (1)
Y41 (23/25)	Q498 (8), T500 (7, 1), N501 (8, 1)	Y484 (9), T486 (8, 1), T487 (8)
Q42 (16/9)	G446 (4, 1), Y449 (4, 1), Q498 (8, 3)	Y436 (5, 1), Y484 (4)
L45 (4/3)	Q498 (3), T500 (1)	Y484 (2), T486 (1)
L79 (2/2)	F486 (2)	L472 (2)
M82 (9/4)	F486 (9)	L472 (4)
Y83 (20/10)	F486 (11), N487 (8, 1), Y489 (1)	N473 (8, 2), Y475 (2)
Q325 (0/4)	–	R426 (2), I489 (2)
E329 (0/6)	–	R426 (6, 1)
N330 (8/11)	T500 (8)	T486 (11, 1)
K353 (50/48)	G496 (7, 1), N501 (11), G502 (4, 1), Y505 (28)	Y481 (1), G482 (3),Y484 (2), T487 (11), G488 (6, 1), Y491 (25)
G354 (11/10)	Y502 (7), Y505 (4)	G488 (7), Y491 (3)
D355 (9/15)	T500 (8, 1), G502 (1)	T486 (8), T487 (3), G488 (4)
R357 (3/4)	T500 (3)	T486 (4)
R393 (1/1)	Y505 (1)	Y491 (1)
Total	288 (16)	213 (11)

The numbers in parentheses of hACE2 residues represent the number of vdw contacts between the indicated residue with SARS-CoV-2-CTD (the former) and SARS-RBD (the latter). The numbers in parentheses of either ligand residues represent the numbers of wdw contacts the indicated residues conferred. The numbers with underline suggest numbers of potential H-bonds between the pairs of residues. wdw contact was analyzed at a cutoff of 4.5 Å and H-bonds at a cutoff of 3.5 Å. See also Table S1.