Table 1. Binding kinetics of mKate, mKate-IgGBP, and SpA to hIgG1, mIgG1, and rIgG2b determined by SPR.
| Molecule | IgG Species | ka pH 7.4 (105/Ms) | kd pH 7.4 (10−3/s) | KD* pH 7.4 (nM) | ka pH 6 (105/Ms) | kd pH 6 (10−3/s) | KD* pH 6 (nM) |
| mKate | Human, Mouse, Rat | – | – | No binding | – | – | No binding |
| mKate-IgGBP | Human | 1.1 | 4.2 | 40 | 2.7 | 5.3 | 19 |
| mKate-IgGBP | Mouse, Rat | – | – | No binding | – | – | No binding |
| SpA | Human | 1.3 | 23 | 2 | 0.8 | 1.2 | 16 |
| SpA | Mouse, Rat | – | – | No binding | – | – | No binding |
(*) Data were fit to a 1∶1 kinetic binding model for derivation of KD.