Fig. 4. Kinetics of ATP hydrolysis for GSTKar3 and Kar3MD.

The MtGSTKar3 (•) or Mt·Kar3MD (▪) complexes were rapidly mixed in the chemical quench flow instrument with [μ-32P]ATP. Final concentrations: 10 μm motor, 30 μm tubulin, 30 μm Taxol, 200 μm MgATP, trace [α-32P]ATP. Each transient (only the first 500 ms shown) was fit to the burst equation (Equation 4), which provided the kinetic constants. GSTKar3: A = 4.4 ± 0.3 μm, k b = 70.8 ± 19.6 s−1, k ss = 4.6 ± 0.4 μm s−1/10 μm sites. Kar3MD: A = 1.9 ± 0.3 μm, k b = 69.8 ± 38.3 s−1, k ss = 5.2 ± 0.3 μm s−1/10 μm sites.