Thermodynamic denaturation of β-lactoglobulin in the presence of cetylpyridinium chloride

• Published in: The Journal of chemical thermodynamics 2010-12, Vol.42 (12), p.1423-1428
• Main Authors: Sahihi, M., Bordbar, A.K., Ghayeb, Y.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cetylpyridinium chloride; Chemical Sciences; Denaturation; Fundamental and applied biological sciences. Psychology; Molecular biophysics; or physical chemistry; Physico-chemical properties of biomolecules; Protein stability; Theoretical and; UV–Vis; β-Lactoglobulin
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2010.06.010

In this work, we determined the stability parameters of bovine β-lactoglobulin, variant A, (BLG-A), in relation to their transition curves induced by cetylpyridinium chloride (CPC) as a cationic surfactant. The experiments took place over the temperature range of 298 K to 358 K. For each transition curve at any specific temperature, the conventional method of analysis, which assumes a linear concentration dependence of the pre- and post-transition base lines, gave the most realistic values for Δ G D(H 2O). Results show that the minimum value of Δ G D(H 2O) occurs at T = 328 K. Using the Gibbs–Helmholtz equation, the values of enthalpy, Δ H D, and entropy, Δ S D, of denaturation have been calculated considering temperature dependence of Δ G D at any specified concentration of CPC. The values of 12.05 kJ · mol −1, 18.54 kJ · mol −1, and 18.32 J · mol −1 · K −1, were obtained for Δ G D(H 2O), Δ H D(H 2O), and Δ S D(H 2O), respectively. The results show that the enthalpy term dominates the entropy term.