Studies in Acoustical properties of Glycyl-Glycyl-Glycine Peptide in 20% Dioxane-Water Mixture at Different Temperatures

Abstract

Ultrasonic velocities and densities of glycyl-glycyl-glycine (GGG) peptide in 20% dioxane-water mixture have been evaluated at different temperatures, 298, 303, 308, 313 and 318 K, by using single crystal interferometer at a frequency of 20 MHz. The ultrasonic velocity, density and concentration were used to calculate (i) partial molal volume φ_v, (ii) adiabatic compressibility β_g, (iii) Apparent molal compressibility φ_k(s), (iv) intermolecular freelength L_f, (v) specific acoustic impedance (Z), and (vi) relative association (R_A) through the light on the solute-solvent and solute-solute interaction. It is observed that φ_v⁰ values increase gradually with increase in temparature, but there is no regular order of φ_k(s)⁰ with respect to temperature. The value of φ_k(s)⁰ decreases up to 303 K and further that the values of φ_k(s)⁰ increase gradually. The data of φ_v⁰ at different temperatures are used to determine that thermodynamic parameters such as free energy ΔG, enthalpy ΔH and entropy ΔS for glycyl-glycyl-glycine in 20% dioxane-water mixture. The values of ΔG, ΔH, ΔS are found to be 3928.4 calories, 8311.22 calories and 278.88 calories respectively. The value of ΔG < 0 and the value of ΔS > 0 indicate the spontaneous process (i.e., forward direction process.)