Table 1.
Interaction of Cardiac S1 with Actin in the Presence of ATP
| S1 | Vmax (s−1) | KATPase (μM) | Catalytic Efficiencyb | Kd (μM)c |
|---|---|---|---|---|
| Nativea | 3.2 ± 0.4 | 15.9 ± 6.8 | 0.19 ± 0.05 | 11.1 ± 3.5 |
| WT | 3.0 ± 0.5 | 21.2 ± 6.8 | 0.14 ± 0.05 | 7.3 ± 0.9 |
| E56G | 3.6 ± 0.4 | 24.4 ±1.8 | 0.15 ± 03 | 5.9 ± 0.6 |
Mean ± SE for n = 3 to six preparations, p < 0.05.
a
Native tissue purified bovine cardiac S1 (unlabeled and unexchanged).
b
Vmax/KATPase (Vmax is the activity at saturating actin, and KATPase is the actin concentration needed for half-maximal activation V = Vmax/2).
c
Dissociation constant for actin and S1 in the presence of saturating ATP.