THE EFFECT OF A DYNAMIC PHASE TRANSITION IN WATER ON THE ELECTROPHYSICAL PROPERTIES OF AQUEOUS ALBUMIN SOLUTIONS

Abstract

Introduction. The structure of human serum albumin (HSA) in aqueous solutions undergoes significant changes depending on temperature, concentration, acid-base balance (pH), the presence of salts, etc.

Methods. The temperature dependence of the zeta potential of human serum albumin macromolecules (1 g/l) in a 0.075 M (0.45 wt. %) aqueous solution of sodium chloride in the temperature range (30–75) °С at the initial pH 7.4 was analyzed.

Results. Experimental values of the zeta potential increase sharply from –27 mV at the temperature of 30°C to zero at around 42°C, and then oscillate near zero up to the denaturation temperature. In the vicinity of 42°С a dynamic phase transition in water occurs, which divides the range of the liquid phase of water into two intervals: in the first interval, the thermal motion of water molecules has a crystal-like character, and in the second interval, water molecules move like ones in argon, i.e. the movement of molecules has an argon-like character.

Conclusions. The analysis shows that the temperature dependence of the zeta potential of albumin macromolecules in dilute aqueous solutions near the temperature of the dynamic phase transition in water is similar to the behaviour of magnetization around the Curie-Weiss critical point for the simplest magnets. Thus, the zeta potential can be considered as an order parameter for the thermodynamic Landau potential, which has the same structure as for the simplest magnets near their Curie-Weiss critical points. Further research will be aimed at studying the peculiarities of the applicability of the revealed analogy for the zeta potential of albumin macromolecules under different conditions of the solution.

References

Barbosa, L.R.S., Ortore, M.G., Spinozzi, F., Mariani, P., Bernstorff, S., & Itri, R. (2010). The importance of protein-protein interactions on the pH-induced conformational changes of bovine serum albumin: A small-angle X-ray scattering study. Biophysical Journal, 98(1), 147–157. https://doi.org/10.1016/j.bpj.2009.09.056

Bardik, V., Fisenko, A.I., Magazu, S., & Malomuzh, N.P. (2020). The crucial role of water in the formation of the physiological temperature range for warm-blooded organisms. Journal of Molecular Liquids, 112818. https://doi.org/10.1016/j.molliq.2020.112818

Bulavin, L.A., Gotsulskyi, V.Y., Malomuzh, N.P., & Fisenko, A.I. (2020). Crucial role of water in the formation of basic properties of living matter. Ukrainian Journal of Physics, 65(9), 794–801. https://doi.org/10.15407/ujpe65.9.794

Snoke, D.W. (2020). Solid State Physics: Essential Concepts (2nd ed.). Cambridge University Press.