Table 2.

Kinetic parameters, similarity score, and EC₅₀ values for the spike neutralizing rabbit monoclonal antibody (mAb2)-RBD/S1 interaction (n=6).

Sample	kon (1/Ms, 105)a	koff (1/s, 10−3)a	KD (nM)a	Similarity scoreb	EC50 (nM)c
Original RBD	32.00	0.35	0.11	N/A	1.5
D614G	5.10	0.51	0.99	21.1	25.1
N501Y	19.40	0.44	0.23	35.6	2.0
N439K	24.70	0.36	0.15	50.6	2.8
Y453F	25.20	0.79	0.31	44.4	2.0
E484K	9.72	1.51	1.55	12.0	12.0

N/A: not applicable.

^aRecorded in 10 mM HBS-EP⁺ buffer, a 1:1 kinetic binding model was fitted to determine the k_on, k_off, and K_D , which was calculated according to equation K_D = k_off/k_on.

^bSimilarity score calculation for each mutant was performed using Sensorgram Comparison tool in the Biacore T200 Evaluation Software.

^cEC₅₀ values were calculated using PLA 3.0 software using unrestricted model.