Table 1. BLI kinetics for immobilized sACE22-IgG1 binding to coronavirus RBDs.
| CoV strain* | WT sACE22-IgG1† | sACE22.v2.4-IgG1 | ||||||
| kon (M−1 s−1) | koff (s−1) | KD (nM) | χ2‡ | kon (M−1 s−1) | koff (s−1) | KD (nM) | χ2 | |
| LYRa11 | 8.7 × 105 | 7.9 × 10−2 | 91 | 0.12 | 1.4 × 106 | 2.5 × 10−3 | 1.8 | 0.10 |
| Rs7327 | 6.4 × 105 | 4.0 × 10−2 | 63 | 0.25 | 9.8 × 105 | 1.8 × 10−3 | 1.9 | 0.11 |
| Rs4231 | 3.2 × 105 | 2.2 × 10−2 | 69 | 0.04 | 4.5 × 105 | 1.6 × 10−3 | 3.5 | 0.10 |
| Rs4084 | 2.9 × 105 | 2.5 × 10−2 | 85 | 0.24 | 4.8 × 105 | 1.5 × 10−3 | 3.1 | 0.10 |
| RsSHC014 | 8.8 × 105 | 2.6 × 10−2 | 29 | 0.20 | 1.6 × 106 | 2.0 × 10−3 | 1.3 | 0.29 |
| SARS-1 | 6.6 × 103 | 1.2 × 10−4 | 58 | 0.03 | 3.0 × 103 | 5.6 × 10−6 | 2.1 | 0.03 |
| SARS-2 | 1.4 × 106 | 8.1 × 10−3 | 16 | 0.25 | 6.6 × 105 | 2.8 × 10−4 | 0.4 | 0.09 |
| SARS-2 (Y449K) | 2.0 × 106 | 9.0 × 10−2 | 46 | 0.67 | 4.3 × 106 | 4.0 × 10−3 | 0.9 | 0.71 |
| SARS-2 (N501W) | 2.4 × 106 | 5.4 × 10−3 | 2.3 | 0.43 | 3.3 × 106 | 2.8 × 10−4 | 0.1 | 0.23 |
| SARS-2 (N501Y) | 2.2 × 106 | 1.8 × 10−3 | 0.8 | 0.15 | 3.6 × 105 | 1.1 × 10−4 | <0.1 | 0.24 |
*Purified RBDs at five to seven concentrations were used as the soluble analytes.
†IgG1 Fc–fused sACE22 was immobilized to anti-human IgG Fc capture biosensors.
‡χ2 values represent the goodness of curve fitting. Acceptable values were considered to be less than 3.