Table 1.
Kinetic rate constants for association ( ka) and dissociation (kd), and equilibrium dissociation constant (KD) of VHH-antigen complexes as determined by SPR spectroscopy with a BIAcore X
| VHH fragments | Antigen | Trpa | ka (M−1 s−1) | kd (s−1) | KD (nM) |
| cAb-Lys3 | Hen lysozyme | 2 | 1.8 105 | 2.0 10−3 | 11 |
| cAb-HuL6 | Human lysozyme | 3 (Trp-100) | 8.6 105 | 5.9 10−4 | 0.7 |
| cAb-NmcA2 | NmcA (β-lactamase) | 3 (Trp-47) | 6.5 106 | 2.1 10−3 | 0.3 |
| cAb-BcII10 | BcII (β-lactamase) | 2 | 1.8 106 | 5.6 10−3 | 3 |
| cAb-TEM2 | TEM-1 (β-lactamase) | 2 | 1.1 106 | 5.0 10−4 | 0.45 |
| cAb-R2 | Azo dye RR6 | 4 (Trp-52a; Trp-58) | 1.6 105 | 4.0 10−4 | 2.5 |
The number of tryptophan residues is also indicated.
a Two tryptophan residues are strictly conserved, namely Trp-36 and Trp-103. Additional tryptophan residues are indicated.