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

Abstract

The apparent molar volumes, V ϕ 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 m B) and magnesium acetate (0.5, 1.0, 1.5, and 2.0 m B) solutions at 298.15 K by the measurement of densities using vibrating-tube digital densimeter. The partial molar volumes, V 2,m 0 obtained from V ϕ have been used to calculate the partial molar volumes of transfer, Δ tr V 2,m 0 for these peptides from water to aqueous solutions of sodium acetate (SA) and magnesium acetate (MA) solutions. The hydration numbers, n H and volumetric interaction coefficients have also been calculated. The Δ tr V 2,m 0 data suggest that ion-charged/or peptide group interactions of peptides are stronger with MA in comparison to SA.