Terahertz spectroscopy as a method for investigation of hydration shells of biomolecules

Water determines the intramolecular dynamics of proteins. En example of bovine serum albumin

In this work, the terahertz time-domain spectroscopy method analyzed solutions of bovine serum albumin (BSA) in two high concentrations (50 and 334 mg/mL) at three pH values (2.5, 6.5, 8.5) and the same solvents without protein, at 25°C. The spectra of dry BSA were also recorded. For the first time, a method for determining the complex dielectric permittivity of protein molecules in aqueous solutions, without the dielectric contribution of the aqueous phase, is proposed. It is shown that the dielectric permittivity of dissolved and dry BSA (lyophilized, in the native conformation) differ significantly in the terahertz frequency range. These differences are small near 70 cm-1, but they increase greatly with decreasing frequency. It was found that the dielectric losses of protein molecules in solution are close to the dielectric losses of the aqueous environment, which in this frequency range are determined by intermolecular relaxation processes of water. Since dielectric losses are directly related to molecular dynamics, this fact shows that the intramolecular dynamics of the protein completely adjusts to the intermolecular dynamics of the aqueous environment. It also indicates that the native conformation does not determine all the fundamental characteristics of a protein molecule, in particular, it does not determine the dynamics of the protein, which significantly depends on the water environment.

Peculiarities of the Dynamical Hydration Shell of Native Conformation Protein Using a Bovine Serum Albumin Example

This paper describes an approach based on the method of terahertz time-domain spectroscopy, which allows the analysis of dynamical hydration shells of proteins with a thickness of 1-2 nm. Using the example of bovine serum albumin in three conformations, it is shown that the hydration shells of the protein are characterized by increased binding of water molecules in the primary hydration layers, and in more distant areas of hydration, on the contrary, the water structure is somewhat destroyed. The fraction of free or weakly bound molecules, usually observed in the structure of liquid water in hydration shells, become more numerous but its average binding is greater than in undisturbed water. The energy distribution of hydrogen bonds in hydration shells is narrowed compared to undisturbed water. All these manifestations of hydration are most pronounced for the native conformation of the protein. Also, the hydration shells of the native protein are characterized by a smaller number of hydrogen bonds and a tendency to decrease their average energy compared to non-native conformations. The fact of a pronounced peculiarity of the hydration shells of the protein in the native conformation has been noted for different proteins before. However, the methodological approach used in this work for the first time allowed this peculiarity to be described by specific parameters of the intermolecular structure and dynamics of water.

The Best Material from the VII Congress of Russian Biophysicists

The purpose of this Special Issue is to demonstrate the current state of research in the field of biophysics in the Russian Federation [...].

Correlation between Hydration States and Self-assembly Structures of Phospholipid and Surfactant Studied by Terahertz Spectroscopy

Phospholipids and surfactants form membranes and other self-assembled structures in water. However, it is not fully understood how the surrounding water (hydration water) is involved in their structure formation. In this paper, I summarize the results of our investigation of the long-range hydration state of phospholipids and surfactants at their surfaces by means of terahertz spectroscopy. By observing the collective rotational dynamics of water in the picosecond time scale, this technique allows us to observe not only the water directly bound to the solute, but also the weakly affected water outside of it. For example, PC phospholipids inhibit water dynamics over long distances, whereas PE phospholipids make water more mobile than bulk water. The causes of this difference in hydration and how it is involved in the structural formation of the membrane are reviewed.

VII Congress of Russian Biophysicists-2023, Krasnodar, Russia

This special issue of Biophysical Reviews contains the materials presented at the VII Congress of Biophysicists of Russia, held from 17 to 23 April in Krasnodar. We believe that we have managed to prepare a selection of articles that well reflects the current state of biophysical science in Russia and its place in the world science. The VII Russian Congress on Biophysics was held in Krasnodar in April 2023, continuing the tradition of the series of biophysics conferences held every 4 years. The congress discussed physical principles and mechanisms of biological processes occurring at different life levels-from molecular to cellular and population levels. The results of fundamental and applied research in molecular biophysics, cell biophysics, and biophysics of complex systems were presented at plenary, sectional, and poster sessions. The works in the field of medical biophysics and neurobiology were especially widely presented. The structure and dynamics of biopolymers and fundamental mechanisms underlying the effects of physicochemical factors on biological systems, membrane, and transport processes were actively discussed. Much attention was paid to new experimental methods of biophysical research, methods of bioinformatics, computer, and mathematical modeling as necessary tools of the research at all levels of living systems. Along with fundamental problems of studying biophysical mechanisms of regulation of processes at the molecular, subcellular, and cellular levels, much attention was paid to applied research in the field of biotechnology and environmental monitoring. The Congress has formed the National Committee of Russian biophysicists.