Table 1. Thermal stability and binding affinity measurements for spike protein designs.

The T_m values are the average of triplicate measurements with the exception of design 10, which was limited by protein quantity. For binding affinity values, the average and SD of triplicate measurements are shown with the exception of design 15, which was not measured because of limited protein quantity. The binding of design 10 to VRC-118 was limited to a single measurement because of limited protein quantity. NM, not measured; NB, no binding.

Designed mutant	Design strategy	Tm1 (°C)	Tm2 (°C)	Binding affinity, Kd (pM)
				ACE2	CR3022	S309	VRC-118	VRC-112
8	NTD + S2	46.38	76.34	160 ± 14	27 ± 4	19 ± 16	9.7 ± 0.4	NB
9	NTD + S2	48.35	79.65	150 ± 5	370 ± 240	44 ± 6	2.9 ± 0.5	NB
10	NTD + S2	46.99	77.44	44 ± 4	2.4 ± 3.3	0.16 ± 0.07	1.9	NB
12	S2 domain	43.72	86.86	100 ± 2	9.0 ± 0.9	11 ± 2	14 ± 8	NB
13	S2 domain	43.75	77.96	65 ± 1	2.2 ± 1.1	20 ± 3	11 ± 1	NB
14	S2 domain	44.18	78.65	190 ± 5	110 ± 51	70 ± 14	25 ± 1	NB
15	S2 domain	44.00	86.54	NM	NM	NM	NM	NM
S-2P		44.13	77.58	200 ± 18	58 ± 26	70 ± 0	42 ± 5	53 ± 4