FIGURE 2.

The ionic strength dependence of the mant-ADP dissociation rate constant. Scallop HMM (0.5 μM) or scS1 (0.5 μM) and 10 μM mant-ADP were mixed with ATP (300 μM) at different [KCl]. (a) Dependence of k_obs values on the [KCl] for scS1 (empty squares) and scHMM in the presence (filled circles) or absence (empty circles) of calcium. (b) The Debye-Huckel plots (log(K_eq) vs. I^0.5) in the presence (filled circles) and absence (empty circles) of calcium. The slopes were 5.94 ± 0.33 and 6.36 ± 0.17 M^−0.5 and the value of K_eq at infinite dilution was found to be 0.14 and 10⁻⁴ in the presence and absence of calcium, respectively.