A study of the conformational changes of beta-lactoglobulin in the vicinity of critical point of binary mixed solvents

作者：Umapathi R; Venkatesu P^*

来源：New Journal of Chemistry, 2016, 40(2): 1747-1755.

DOI：10.1039/c5nj02273h

In this study, we present the influence of bovine milk beta-lactoglobulin (beta-LG) as an impurity on the critical mixture of isobutyric acid (IB) + water (W) using density (rho) coexistence curve, fluorescence spectroscopy and dynamic light scattering (DLS) measurements. Furthermore, the coexistence curve density data used to obtain the critical exponents (beta), which depict the shape of the coexistence curve. Our experimental results explicitly elucidate that the critical region of IBW decreases with an increasing concentration of beta-LG. The critical temperature (T-c) of IBW can be modulated by the addition of different concentrations of beta-LG. The modulation in the T-c values can be attributed to the beta-LG induced interactions of solvent molecules with the residues of beta-LG. The observed deviations in the T-c with temperature predict unambiguously the formation of the solvation structure at T-c for the critical mixture in the absence as well as in the presence of beta-LG. Our results show that beta-LG can significantly affect the critical binary mixture of IBW. On the experimental side and to the best of our knowledge, this is the first experimental evidence that most of the protein entangles in the upper, IB-rich phase.

• 出版日期2016