Table 6.
Affinity in-solution dissociation constants of plasma-derived C3b and C4b to CR1 variants
| Human CR1 truncation | Affinity in solution to pdC3b KD (nM) | Affinity in solution to pdC4b KD (nM) |
|---|---|---|
| LHR-A | No binding | 1231.0 ± 116.9∗∗ |
| LHR-AA | ND | 1545.0 ± 54.7∗∗ |
| LHR-B | 336.6 ± 28.8∗∗ | 1913.7 ± 175.2∗∗ |
| LHR-AB | 305.3 ± 22.6∗∗ | 530.2 ± 32.1∗ |
| LHR-BC | 78.2 ± 10.4 | 581.2 ± 43.0∗ |
| LHR-ABC/CSL040 | 76.4 ± 4.3 | 352.8 ± 15.5 |
| LHR-BBC | 44.4 ± 4.2∗ | 317.0 ± 23.2 |
| LHR-ABCC | 44.6 ± 2.1∗∗ | 249.1 ± 20.1∗ |
| LHR-BBCC | 34.8 ± 1.8∗∗ | 218.6 ± 4.8∗∗ |
Shown in this table are the mean ± SD in-solution affinities (nM) for each CR1 variant binding to plasma-derived C3b (pdC3b) and C4b (pdC4b), based on N = 3 experiments. KD is the equilibrium dissociation constant of the interaction, calculated from sensorgram data fitted to a 1:1 affinity in-solution binding model. See Figure 7, B and C for the graphical data used to generate these values. Statistically significant differences for individual CR1 fragment affinities compared to CSL040 were calculated by an unpaired t test; ∗ p < 0.005; ∗∗ p < 0.0005.
CR1, complement receptor 1; LHR, long homologous repeat; ND, not done.