TABLE 3.

Activation energy in the EP transition E1PCa₂ → E2P + 2Ca²⁺

Activation energy of the EP transition (ΔG^‡) was calculated for the wild type according to the transition state theory (28), ΔG^‡ = −RT ln (hk₃/κT), by using the rate (k₃) determined at 0.1 m KCl and at the intercept of the plot in KCl, γ_±² = 0 (KCl) (Fig. 5). Here, R, T, h, and κ are the gas constant, absolute temperature, Planck constant, and Boltzmann constant, respectively. ΔΔG^‡ is obtained by subtracting ΔG^‡ at γ_±² = 0 (KCl) from ΔG^‡ at 0.1 m KCl, and represents the reduction of the activation energy, i.e. the stabilization of the transition state in the reaction by the electrostatic energy in 0.1 m KCl.

	log k3	k3	ΔG‡
		s−1	kJ/mol
γ±2 = 0 (KCl)	−2.57	0.0027	80.1
0.1 m KCl	−1.14	0.072	72.7
ΔΔG‡			−7.4