The Effect of Temperature on the Volume Properties of L-Lysine in Aqueous and Aqueous Buffer Solutions

Abstract

The behavior of L-lysine (Lys) in water and an aqueous buffer solution is studied by densimetry as the temperature varies from 288.15 to 313.15 K with an interval of 5 K. Based on the experimental density values of amino-acid solutions, the apparent molar volumes and partial molar volumes of Lys are determined at an infinite dilution in water and buffer solution at each temperature. The effects of temperature, medium, and amino-acid concentration on volumetric characteristics are revealed. The partial molar extensibility and their derivatives with respect to temperature, the values of which indicate the structurally destructive behavior of Lys in the studied solutions, are determined. It is found that the structurally destructive effects of Lys are enhanced in an aqueous buffer solution. It is shown that the partial molar volumes of amino-acid transfer from water to the buffer solution have positive values in the studied temperature range. The results obtained are discussed on the basis of various types of molecular interactions between a solute and a solvent using the Gurney model.