Table 1. ATPase Activity and Motility of Kinesin Derivatives.

^aSchematic diagrams of enzyme species present, using the same symbols as in Figure 1.

^bMicrotubule-stimulated ATPase specific activity per dimer (rows 1−3) or per monomer (row 4) in 1 mM ATP, 1.2 mg/mL microtubules, 25 °C.

^cIn single-molecule bead movement assay at 1:1 enzyme dimer:bead mole ratio, 1 mM ATP, 22−23 °C.

^dData set included some runs where motor ran off the microtubule end.

^eNo motility detected. Value given is the detection limit.

^fImplies that heterodimer specific activity is ∼15 s⁻¹, since the preparation is estimated by gel densitometry to contain ∼35% mutant homodimers, which have negligible activity.

^gNot determined.