Interactions in L-alanine-/L-proline-/L-valine-/L-leucine-aqueous KCl/KNO3 systems at different temperatures: An isentropic compressibility study

Ultrasonic velocity and density values of amino acids: L-alanine/L-proline/L-valine/L-leucine in 2.0 M aqueous KCl and 2.0 M aqueous KNO3 solutions have been measured for several concentrations of amino acids at different temperatures: 298.15,303.15,308.15,313.15,318.15 and 323.15 K Using ultrasonic velocity and density data, the thermodynamic parameters such as isentropic compressibility (kappa(s)), change in isentropic compressibility (Delta kappa(s)) and relative change (Delta kappa(s)/kappa(0)) in isentropic compressibility have been computed. The trends in the behaviour of kappa(s), Delta kappa(s) and Delta kappa(s/)kappa(0) with changes in the concentration of amino acids/zwitterions as well as in temperature have been discussed in terms of zwitterions-ions, zwitterions-water dipoles, ions-ions, ions-water dipoles intermolecular/interionic interactions operative in the said systems. (C) 2008 Elsevier B.V. All rights reserved.