Thermodynamic properties of peptide solutions 3. Partial molar volumes and partial molar heat capacities of some tripeptides in aqueous solution

Partial molar volumes, V₂^o, and partial molar heat capacities, C_p,2^o, of the tripeptides glycylglycylglycine, glycylglycylalanine, glycylalanylglycine and alanylglycylglycine have been determined in aqueous solution at 25°C. For the three alanyl-containing tripeptides, the data indicate that the tripeptide-water interaction is influenced by the side chain position within the molecule. The results have been rationalized in terms of likely solutesolvent interactions. The V₂^o and C_p.2^o data have also been used to calculate the contribution to these properties of a-CH₃ side chain.