TABLE 1.

Parameters measured in EGTA and pCa 4

	EGTA	pCa 4
Biochemical data
Vmax of ATPase (Pi molecules s−1 head−1)	77.7 ± 3.1	70.9 ± 4.9
Km for ATPase (μm)	10.0 ± 1.1	11.0 ± 2.1
kcat/Kapp (m−1 s−1)	7.8 × 106	6.4 × 106
Molecular configuration (EM)
Length from neck base to head tip (nm)	32.8 ± 6.0	27.1 ± 5.7
In vitro assay (ensemble, 960 myosin molecules μm−2)
Vmax(e) (μm s−1)	4.3 ±0.7	1.5 ± 0.8
Bead assay (single molecule)
Vmax(s) (μm s−1)	6.8 ± 3.3	5.1 ± 1.8
Run length at 1 mm ATP (μm)	1.3 ± 0.3a	1.3 ± 0.1
Step size (nm)
Low load (<0.5 pN)	36.1 ± 0.5	27.5 ± 0.4
High load (0.5–1 pN)	35.5 ± 0.4	22.1 ± 0.2
Force (pN)	0.82 ± 0.45	0.55 ± 0.29

^a Determined in a previous study (9).