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. 2017 Nov 6;149(11):1029–1039. doi: 10.1085/jgp.201711788

Table 1. Binding cooperativity of melibiose and Na+ to MelBSt.

Parameter Na+ binding (NaCl in syringe) Melibiose effect on Na+ binding Melibiose binding (melibiose in syringe) Na+ effect on melibiose binding
No sugar (n = 4) With melibiose (n = 2) No NaCl (n = 3) With NaCl (n = 5)
Apparent Kd (mM) or affinity increase 0.64 ± 0.02a 0.08 ± 0.01 8-fold 9.28 ± 0.23 1.09 ± 0.06 8.5-fold
ΔG or ΔΔG (kJ/mol) −18.24 ± 0.08 −23.52 ± 0.13 −5.28 (P < 0.05)b −11.60 ± 0.06 −16.93 ± 0.14 −5.33 (P < 0.05)

ITC data were collected at pH 7.45 and 25°C with MelBSt in sample cell as described in Materials and methods. ΔG, binding free energy; ΔΔG, thermodynamics coupling free energy. n = number of test from a total of 5 different batches of MelBSt purification.

a

Standard error (SEM).

b

Unpaired t test.