Kinetics of interaction between immobilized p97 and pro-uPA or plasminogen using the 2-state conformational model
Immobilized protein . | Ligand . | ka1, × 104 M-1 s-1 . | ka2, × 10-3 s-1 . | kd1, × 10-3 s-1 . | kd2, × 10-4 s-1 . | KD, × 10-9 M . |
|---|---|---|---|---|---|---|
| p97 | Pro-uPA | 0.6 | 3.2 | 1.7 | 7.1 | 65 |
| p97 | Plasminogen | 2.1 | 6.0 | 43.0 | 11.2 | 350 |
Immobilized protein . | Ligand . | ka1, × 104 M-1 s-1 . | ka2, × 10-3 s-1 . | kd1, × 10-3 s-1 . | kd2, × 10-4 s-1 . | KD, × 10-9 M . |
|---|---|---|---|---|---|---|
| p97 | Pro-uPA | 0.6 | 3.2 | 1.7 | 7.1 | 65 |
| p97 | Plasminogen | 2.1 | 6.0 | 43.0 | 11.2 | 350 |
Kinetic parameters were based on a 2-state conformational change binding model using the biosensorgram shown in Figures 1 and 2. This model describes a 1:1 binding of analyte to immobilized ligand followed by a conformational change in the complex. It is assumed that the conformationally changed complex can dissociate only through the reverse of the conformational change: A + B = AB = ABx. The dissociation constants (KD) were derived using both association (ka) and dissociation (kd) rates [KD = (kd1/ka1) (kd2/ka2)]. The parameters are ka1, association rate constant for A + B1 = AB1 (M-1 s-1); kd1, dissociation rate constant for AB1 = A + B1 (s-1); ka2, forward rate constant for AB = ABx (s-1); kd2, backward rate constant for AB = ABx (s-1). Mean χ2 values for the sensorgram fits were less than 0.4.