TABLE 1.

Tentative assignment of the infrared peaks induced by Na⁺ binding to MelB

H2O	D2O	Assignment
1742	1741	Lipid
1725	1716	COOH (with a possible lipid contribution)
1700	1690	Asp/Glu/solvent-accessible reverse turn
1687	1687	β-sheet
—	1678	Solvent-accessible turn-like structure
1671	1670	Turn/αII-helix
1662	1662	α-helix
1657	1657	α-helix
1651	1651	α-helix
—	1646	Open loops
1641	1639	β-sheet
1599	1599	COO− (antisymmetric stretching)
1576	1576	COO− (antisymmetric stretching)
1551	1450	Amide II vibration
1540	1540	Amide II vibration
1403	1403	COO− (symmetric stretching)
1384	1385	COO− (symmetric stretching)

Data for peak assignment are taken from (30,34,42,45).