Table I. Energetic decomposition for... | Rockefeller University Press

Table I.

Energetic decomposition for KcsA and KcsA-G77A_D

		KcsA	KcsA-G77A_D
	$Δ μ^{ex} (S)$	−15.7	−10.0
	$Δ W_{local}$	−15.8	−9.9
	TΔs^ex	1.3	−1.1
	$T Δ s_{local}^{ex}$	2.1	4.7
Ion–site	$Δ 〈 ε_{local} 〉$	−21.0	0.8
Ion–medium	$Δ 〈 ε_{m} 〉$	2.2	−20.1
Site–site	$Δ 〈 U_{s} 〉$	7.3	−6.0
Site–medium	$Δ 〈 U_{s-m} 〉$	−2.9	14.5
Medium–medium	$Δ 〈 U_{m} 〉$	0.0	−0.3
Fluctuation (total)	$Δ μ_{fluc}^{ex}$	3.1	9.3
Fluctuation (local)	$Δ W_{local,fluc}^{ex}$	5.2	−10.7

		KcsA	KcsA-G77A_D
	$Δ μ^{ex} (S)$	−15.7	−10.0
	$Δ W_{local}$	−15.8	−9.9
	TΔs^ex	1.3	−1.1
	$T Δ s_{local}^{ex}$	2.1	4.7
Ion–site	$Δ 〈 ε_{local} 〉$	−21.0	0.8
Ion–medium	$Δ 〈 ε_{m} 〉$	2.2	−20.1
Site–site	$Δ 〈 U_{s} 〉$	7.3	−6.0
Site–medium	$Δ 〈 U_{s-m} 〉$	−2.9	14.5
Medium–medium	$Δ 〈 U_{m} 〉$	0.0	−0.3
Fluctuation (total)	$Δ μ_{fluc}^{ex}$	3.1	9.3
Fluctuation (local)	$Δ W_{local,fluc}^{ex}$	5.2	−10.7

The eight carbonyl ligands comprise the local site. We consider the water molecules in the S₁ and S₃ sites adjoining the S₂ site as the medium. $Δ μ^{ex} (S)$ and $Δ W_{local}$ are obtained using thermodynamic integration. The selectivity in the KcsA system is 5.0 kcal/mol considering the site plus the medium, and it is 4.9 kcal/mol for the eight-carbonyl model. Fluctuation (total), the fluctuation contribution for the site plus two-water system; Fluctuation (local), the fluctuation contribution for the site alone. Note that these values are comparable to the selectivity free energy. All values are in kcal/mol.

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