Table 3.
Binding affinity of IgG for PAB variants
| |
pH = 7.4 |
pH = 5.0 |
||
|---|---|---|---|---|
| Protein | K D (×10 −9 ) (M −1 ) | K D ratio | K D (×10 −9 ) (M −1 ) | K D ratio |
| PAB01 (WT) |
5.1 ± 3.2 |
- |
7.6 ± 4.3 |
- |
| PAB02 (D36H) |
33.6 ± 19.2 |
6.6 |
832 ± 443 |
110 |
| PAB03 (Q9H, D36H) |
288 ± 146 |
56 |
ND |
- |
| PAB04 (Q10H, D36H) |
6830 ± 3600 |
1300 |
ND |
- |
| PAB05 (R27H, D36H) |
80.7 |
16 |
2090 |
270 |
| PAB06 (K35H, D36H) |
550 ± 143 |
110 |
3860 |
510 |
| PAB07 (Q9H) |
13.9 ± 6.3 |
2.7 |
30.6 |
4 |
| PAB08 (Q10H) |
50.8 ± 20.5 |
10 |
951 |
120 |
| PAB09 (R27H) |
5.6 ± 1.3 |
1.1 |
7.0 |
0.92 |
| PAB10 (Q32H) | 2.8 ± 1.3 | 0.55 | 96.8 | 13 |
The binding assay was performed under neutral (pH = 7.4) and acidic (pH = 5.0) conditions using SPR. The IgG was immobilized on the surface of a CM5 sensor chip (GE Healthcare).
KD, equilibrium dissociation constant: KD ratio, (KD of histidine-substituted PAB variant)/(KD of Wild-type PAB): ND, not determined.