TABLE 1.
Kinetic parameters and affinity constants derived from the SPR analysis of NP-IgE and R334S NP IgE binding to immobilized FcεRIα
Both IgEs were analyzed using a biphasic interaction model from which association and dissociation constants were derived for each component (shown ± S.D. for at least five determinations in the concentration range 12.5–100 nm). R1/R0 describes the fractional contribution of the first component to the overall fit.
| Constant | NP-IgE | R334S NP-IgE | Deviation of R334S NP-IgE from NP-IgE |
|---|---|---|---|
| ka1 (m-1 s-1) | (0.85 ± 2.7) × 105 | (1.27 ± 0.24) × 105 | Within error |
| kd1 (s-1) | (2.14 ± 0.48) × 10-2 | (1.32 ± 0.16) × 10-2 | Within error |
| ka2 (m-1 s-1) | (1.88 ± 0.51) × 105 | (8.25 ± 2.3) × 104 | ∼2× slower |
| kd2 (s-1) | (1.23 ± 0.31) × 10-4 | (1.71 ± 0.12) × 10-3 | ∼10× faster |
| Ka1 (m-1) | 0.40 × 107 | 0.96 × 107 | Within error |
| Ka2 (m-1) | 1.53 × 109 | 4.68 × 107 | ∼33× lower |
| R1/R0 | 0.03 ± 0.01 | 0.31 ± 0.04 |