Table 1. Binding cooperativity of... | Rockefeller University Press

Table 1.

Binding cooperativity of melibiose and Na⁺ to MelB_St

Parameter	Na⁺ binding (NaCl in syringe)		Melibiose effect on Na⁺ binding	Melibiose binding (melibiose in syringe)		Na⁺ effect on melibiose binding
Parameter	No sugar (n = 4)	With melibiose (n = 2)	Melibiose effect on Na⁺ binding	No NaCl (n = 3)	With NaCl (n = 5)	Na⁺ effect on melibiose binding
Apparent K_d (mM) or affinity increase	0.64 ± 0.02^{^a}	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)

Parameter	Na⁺ binding (NaCl in syringe)		Melibiose effect on Na⁺ binding	Melibiose binding (melibiose in syringe)		Na⁺ effect on melibiose binding
Parameter	No sugar (n = 4)	With melibiose (n = 2)	Melibiose effect on Na⁺ binding	No NaCl (n = 3)	With NaCl (n = 5)	Na⁺ effect on melibiose binding
Apparent K_d (mM) or affinity increase	0.64 ± 0.02^{^a}	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 MelB_St 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 MelB_St purification.

Standard error (SEM).

Unpaired t test.

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