Table 1.
Receptor binding, bioactivity, and stability properties of wtIL5 and monomeric IL-5s
| kon, M−1·s−1 × 10−5 | koff (s−1 × 10−3) | Kd, nM (ratio of rates) | Kd, nM (steady-state) | Stoichiometry, mol shIL5Rα/mol IL5 (from steady-state) | TF-1 EC50, pM | B13 EC50, pM | Tm, °C | ΔH, kcal/mol | |
|---|---|---|---|---|---|---|---|---|---|
| wtIL5 | 10.5 ± 1.3 | 2.5 ± 0.1 | 2.4 ± 0.2 | 0.9 ± 0.1* | 3 | 9 | 67.9 ± 0.2 | 155 ± 3 | |
| DABC | 2.5 ± 0.3 | 25 ± 0 | 100 ± 14 | 134 ± 8 | 1.1 ± 0.02 | 12 | 2,201 | 59.7 ± 0.5 | 43 ± 3 |
| GM1 | 2.2 ± 0.1 | 23 ± 1 | 105 ± 4 | 122 ± 17 | 1.0 ± 0.08 | 24 | 170 | 63.8 ± 0.2 | 49 ± 1 |
Rate constants, equilibrium constants, and stoichiometries were from optical biosensor analyses. TF-1 and B13 cell proliferation activities are given as the concentrations required from half maximal stimulation. Unfolding Tm and ΔH values are from CD measurements.
*
For wtIL5, stoichiometry was obtained from extrapolation of kinetic data, and no steady-state Kd is reported, since the kinetic sensorgrams did not form definitive steady state plateaus for this form.