Thermodynamic Behavior of Systems Containing Amino Acids in Aqueous-Lactose Solutions

Abstract

The hydration of proteins plays a vital role in biological systems, which inspires us to study the molecular interactions in solutions containing amino acids + water + lactose at different temperatures. Therefore, in view of the biological implications of the hydration behavior of amino acids, in the present document we report the key thermodynamic properties: standard molar volumes, $$V_{2,\phi }^{0}$$, and standard molar compressions, $$\kappa_{S,2,\phi }^{0}$$ of glycine, l-serine, l-proline, l-arginine and l-asparagine in 0.10, 0.30 and 0.50 mol·kg−1 aqueous solutions of lactose from density and ultrasonic velocity data at different temperatures, which helps us to understand the effect of lactose on the hydration of the amino acids. We have also reported refractive indices and molar refractions of the studied systems. The results reveal that lactose has a significant effect on the hydration and electrostriction behavior of the amino acids in general and has a dehydration effect in particular on the amino acids. The results have implications in the role of proteins in biological systems.