Interactions of some peptides with sodium acetate and magnesium acetate in aqueous solutions at 298.15Â K: A volumetric approach

The apparent molar volumes, Vϕ of diglycine, triglycine and glycyl-l-leucine have been determined in water and in aqueous sodium acetate (0.5, 1.0, 2.0, and 4.0 mB) and magnesium acetate (0.5, 1.0, 1.5, and 2.0 mB) solutions at 298.15 K by the measurement of densities using vibrating-tube digital densimeter. The partial molar volumes, V2,m0 obtained from Vϕ have been used to calculate the partial molar volumes of transfer, ΔtrV2,m0 for these peptides from water to aqueous solutions of sodium acetate (SA) and magnesium acetate (MA) solutions. The hydration numbers, nH and volumetric interaction coefficients have also been calculated. The ΔtrV2,m0 data suggest that ion-charged/or peptide group interactions of peptides are stronger with MA in comparison to SA.