Table 3. Thermodynamic parameters for SO₄^2- binding to DHNTPase.

	SO42-
n	2.0
Ka1 (M-1 x 104)	11.2 (0.1)
ΔH1 (kcal mol-1)	5.7 (0.2)
TΔS1 (kcal mol-1)	11.7 (0.2)
ΔG1 (kcal mol-1)	- 6.0 (0.5)
Ka2 (M-1 x 104)	2.9 (0.2)
ΔH2 (kcal mol-1)	9.43 (0.24)
TΔS2 (kcal mol-1)	14.2 (0.3)
ΔG2 (kcal mol-1)	- 4.77 (0.37)

The value shown is the mean of three replicate experiments.

The number in parentheses is the standard deviation.