Table 1.

Equilibrium Ratio Values from ITC for EDTA:Ca²⁺ Binding ^a

	reactant concentrations (mM)
[EDTA]0	0.500	2.50	7.50	12.5
[CaCl2] b	0.428	2.14	6.42	10.7
T (°C)	equilibrium ratio, Ki/105 (M−1 ± error of fit)
5.0	22.3 ± 0.6	16.6 ± 0.8	7.88 ± 1.01	4.86 ± 0.61
25.0	13.4 ± 0.3	10.6 ± 0.3	6.58 ± 0.29	4.48 ± 0.14
37.0	10.6 ± 0.4	9.46 ± 0.32	6.43 ± 0.45	4.43 ± 0.35
50.0	8.53 ± 0.47	8.01 ± 0.47	5.96 ± 0.76	4.24 ± 0.43

^aAll ITC solutions contain 150 mM MES, pH 6.2.

Percent error of precision ≤ 5% for all K_i values, based on three or more trials at each condition.

^bThe total [CaCl₂] in the ITC cell, one injection prior to surpassing a 1:1 molar ratio of Ca²⁺/EDTA.