. Author manuscript; available in PMC: 2009 Dec 14.

Published in final edited form as: J Biol Chem. 2006 Sep 26;281(47):35779–35784. doi: 10.1074/jbc.M607232200

TABLE 3. Thermodynamic parameters for NPG binding in NaP_i or Tris.

Experiments were carried out in NaP_i or Tris, pH 7.5, as indicated, at 20 °C as described under “Experimental Procedures.”

LacY	Buffer	ΔH^app	ΔG^a	TΔS^b	ΔS	n_H+^c
		kcal·mol⁻¹	kcal·mol⁻¹	kcal·mol⁻¹	cal·mol⁻¹·K⁻¹
Wild type	P_i	−2.2	−6.6	4.4	15.0	0.05
	Tris	−1.7	−6.8	5.1	17.4
C154G	P_i	−13.5	−7.1	−6.4	−21.8	−0.04
	Tris	−13.9	−6.6	−7.3	−25.0

ΔG was calculated from the equation ΔG = −RT lnK_a.

TΔS were calculated from the equation TΔS = ΔH − ΔG.

n_H+ = [ΔH^app(P_i) − ΔH^app(Tris)]/[H_i^Pi − ΔH_i^Tris].

TABLE 3. Thermodynamic parameters for NPG binding in NaPi or Tris.