Table II.
Equilibrium Parameters for the Interaction of ADF with G- and F-actin
| Parameter | Conditions | MgATP-actin | MgADP-actin | |||
|---|---|---|---|---|---|---|
| K DG (μM) | G buffer | 0.08 ± 0.02 | 0.025 ± 0.005 | |||
| F buffer (1 mM MgCl2) | 0.15 ± 0.03 | ND | ||||
| F buffer (0.1 M KCl, 1 mM MgCl2) | 8 ± 2 | 0.1 ± 0.02 | ||||
| F buffer (0.4 M KCl, 1 mM MgCl2) | 20 ± 5 | ND | ||||
| K DF (μM) | F buffer (0.1 M KCl, 1 mM MgCl2) | >10 (ND) | 0.3 (calculated) | |||
| C SS (μM) | Free barbed ends | 1.7 ± 0.2 | 4.5 ± 0.5 | |||
| Capped barbed ends | 3.5 ± 0.3 | 4.5 ± 0.5 |
K DG and K DF are the equilibrium dissociation constants for binding of ADF to G- and F-actin, respectively. C SS is the steady-state concentration of unassembled actin at saturation by ADF, measured at pH 7.8 under physiological ionic conditions.