Table 2.

Kinetic parameters of monobodies against the SARS-CoV-2 wild type and variants of concern receptor-binding domain determined by BLI.

Receptor-binding domainParametersC4C4-AM2C6bC12b
WT (B.1.1)KD (nM)0.96<0.010.510.67
kon (1/Ms) × 1052.
koff (1/s) × 10−42.3<0.010.631.1
Alpha (B.1.1.7)KD (nM)0.38<0.010.780.54
kon (1/Ms) × 1052.
koff (1/s) × 10−41.1<
Beta (B.1.351)KD (nM)N.D.
kon (1/Ms) × 105N.D.
koff (1/s) × 10−4N.D.160.310.39
Gamma (P.1)KD (nM)N.D.4.40.880.66
kon (1/Ms) × 105N.D.
koff (1/s) × 10−4N.D.150.890.65
Delta (B.1.617.2)KD (nM)N.D.
kon (1/Ms) × 105N.D.1.90.761.4
koff (1/s) × 10−4N.D.
  • The data for the wild type were the same as in Table 1. N.D., not determined.