Table II.

Kinetic constants for the acto-S1 kinetic cycle

	Wt	Wt-1	Sm	Sm-6	Ca	Ca-7
Steady-state ATPase
Basal (s−1)	0.12	0.11	0.11	0.11	0.13	0.11
kcat (s−1)	11	1	9	8	2	11
Kactin (μM)	80	38	116	5	67	178
kcat/Kactin (s−1μM−1)	0.13	0.02	0.08	1.6	0.02	0.06
ATP binding to A·M
K1′k+2′ (μM−1s−1)	0.18	0.49	0.32	0.20	0.48	0.41
k+2′ (s−1)	263	754	427	421	580	423
1/K1′ (μM)a	1461	1539	1334	2105	1208	1032
ADP binding to A·M
K5′ (μM)	161	182	276	261	261	217
Actin binding to myosin
k−6 (μM−1s−1)	0.93	0.94	2.6	2.4	1.4	1.5
k+6 (s−1)	0.0007	0.13	0.006	0.0002	0.065	0.003
K6 (μM)b	0.0008	0.14	0.002	0.0001	0.046	0.002

^aCalculated from k_+2′/K_1′k_+2′. Similar values were obtained from the hyperbolic fits of Fig. 5A (not shown).

^bCalculated from k₋₆ and k₊₆.