[Change in conformation of proteins in aqueous solutions of heterofunctional nonelectrolytes]. / Izmenenie konformatsii belkov v vodnykh rastvorakh geterofunktsional'nykh neélektrolitov.

In narrow ranges of concentrations of heterofunctional nonelectrolytes in aqueous solutions, structural transitions occur, which manifest themselves in the self-association of nonelectrolytes molecules and are accompanied by the screening of their hydrophobic groups from the contact with the solvent. In the same nonelectrolytes concentration ranges, conformational changes of protein molecules in solutions take place. The compatibility of the concentration ranges of these two processes is due to the fact that when nonelectrolytes molecules are extruded from the network of hydrogen bonds during the structural transition, both the self-association of nonelectrolytes molecules and their incorporation into the hydrate shell of the protein occur. The dehydration of the protein results in the disturbance of the balance of intra- and intermolecular interactions maintaining the native protein structure, which leads to the rearrangement of the macromolecule conformation.

[Structure of an Escherichia coli bacterial suspension]. / Struktura bakterial'noi suspenzii Escherichia coli.

The structure of bacterial suspensions of Escherichia coli M-17 at the counting concentrations of the cells 10(7), 10(8), 10(9) i/ml and in the temperature range of (18-50) degrees C has been investigated by means of orientational conductometric, electron microscopic and UV-spectroscopic methods. On the basis of experimental relationships of the anisotropy of suspensions electric conductivity upon the intensity of a sinusoidal electric field and relaxation of anisotropy after switching off the field the function of the distribution of bacteria with respect to their sizes was evaluated at different temperatures and concentrations. The conductometric function of bacteria distribution is in a good agreement with the analogous function obtained with the help of the electron microscope. In accordance with the functions the suspension of E. coli contained three kinds of cells: high electronic density, low electronic density bacteria and bacteria aggregates. Relative amounts of every kind of bacteria depended on temperature and concentration of cells. The minimum of bacteria aggregates and maximum of low electronic density cells were obtained in the temperature range of (32-42) degrees C. This fact could be explained by the activation of the transport membrane systems in this temperature range. This hypothesis was confirmed by the UV-spectroscopic method.

[Temperature changes of extracellular media state on a bacterial suspension]. / Temperaturnye izmeneniia sostoianiia vnekletochnoi sredy v bakterial'noi suspenzii.

Within temperature intervals 30-40 degrees C for bacterial suspension of E. coli and 24-34 degrees C for B. flavum the extracellular medium exists in a specific state. Water in the extracellular medium is stabilized by increased hydrophobicity of extracellular protein molecules surface due to proteins conformational change. The total amount of UV-absorbing metabolites is decreased as a result of activation of microorganisms transport systems. The temperature intervals of these processes are different for both types of the microorganisms and coincide with their temperature optima of vital activity.

[Changes in heat capacity upon protein denaturation]. / Ob izmenenii teploemkosti pri denaturatsii belkov.

By the use of infrared spectroscopy it has been shown that the configurational heat capacity of hydrogen bonds represents the principal contribution into the denaturational change of heat capacity of proteins.

[Thermostability of protein structure in the native state and mechanisms of its maintenance]. / Termostabil'nost' struktury belkov v nativnom sostoianii i mekhanism ee podderzhaniia.

A comparison of temperature changes of the protein spectra with temperature behavior of other systems with hydrogen bonds shows high thermostability of the functional active structure of protein molecules. The stability of proteins space organization is regulated and supported by non-monotonous temperature changes of this organization. The physical mechanism of thermostabilization includes interaction of hydrophobic radicals of protein with the aqueous environment.

[Nonmonotonous character of temperature changes in protein conformation in predenaturational regions of temperatures]. / Nemonotonnyi kharakter temperaturnykh izmenenii konformatsii belkov v preddenaturatsionnoi oblasti temperatur.

Temperature changes of protein infrared spectra have a nonmonotonous pattern. On the curves of temperature relationships of spectral characteristics the regions of high frequency displacement have been observed, interrupted by sharp low frequency shifts, partly or entirely compensating the displacement of the bands in the preceding temperature interval. It has been shown that at temperatures corresponding to the high frequency displacement heat weakening of the strength of hydrogen bonds takes place. At the low frequency shifts the whole system of the hydrogen bonds has an opposite change of the state maintaining high stability level of protein macromolecules in the broad temperature range.