[Determination of the content of water in dry preparations of the vaccine strain Francisella tularensis by NMR-relaxation technique].

Frozen-dried preparations were studied for the impact of moisture content of the nuclear magnetic resonance parameter that was a ratio of the amplitudes of a slow component and a rapid one of a free induction signal from the protons of samples. It was found that there was a linear correlation between this parameter and the moisture content of biological materials, by using bovine serum albumin (BSA) as examples, with lactose and biomass of Francisella tularensis. Formulas were derived for calculating the moisture content of the test preparations.

[Physiologic and physico-chemical mechanisms of the resistance of microorganisms to freezing and drying]. / K voprosu o fiziologicheskikh i fiziko-khimicheskikh mekhanizmakh ustoichivosti mikroorganizmov k zamorazhivaniiu i vysushivaniiu.

The influence of osmotic stress and temperature on physiologo-biochemical state of microbial cells intended for freeze-drying has been analysed. Molecular mechanisms of cryo- and xeroprotective effect of protectors are dealt with in the paper.

[The effect of dimethylsulfoxide and thiourea on the water diffusion permeability of the E. coli membrane]. / Vliianie dimetilsul'foksida i tiomocheviny na diffuzionnuiu vodnuiu pronitsaemost' obolochek E. coli.

It is shown that diffusive water permeability of E. coli cell membranes at 4-24 degrees C is in the range from 16.6 to 35.0 microM.s-1, that is close to erythrocyte membrane water permeability, but higher than that of lipid bilayers. Cryoprotectants (DMSO and thiourea) at the concentration of 1.0 M considerably decrease water bacterial membrane permeability. 1.5- and 2-fold, respectively. The obtained results are discussed in relation to two possible water transport ways through pores of the protein nature or lipid bilayer damages.

[NMR study of the structural transition in the DNA-bound water system in the interval of physiological temperatures]. / Issledovanie metodom IaMR strukturnogo perekhoda v sisteme DNK-sviazannaia voda v oblasti fiziologicheskikh temperatur.

Temperature dependence of spin-spin proton relaxation times of DNA and bound water and the content of bound water in the samples of DNA, saturated with water in the atmosphere with different relative humidities from 0 to 100% were studied by means of pulsed NMR. It is shown that the temperature transition in the system of DNA-bound water in the interval 18-35 degrees is observed only when the relative humidity is more than 70% and the double-stranded structure of DNA exists. The transition of DNA from one conformation into another passes through some intermediate state more labile and probably less ordered. This transition is accompanied by changes in the structure of the hydration shell. In the case when relative humidity is greater than 80%, the partial dehydration of DNA stimulated by the transition is observed. This dehydration increases with the increase of relative humidity.

[Permeability and damage of the erythrocyte membrane at -1 degree C to -9 degrees C shown by the NMR relaxation method]. / Pronitsaemost' i povrezhdenie membran éritrotsitov pri temperaturakh ot -1 gradus C to -9 gradusov C po dannym metoda IaMR-relaksatsii.

Amount of inter--and extracellular unfrozen water in the intact human erythrocytes as well as tau a, "a life time" of water molecules in these cells, have been determined. The progressive compression of the erythrocytes during freezing them as deep as -5 degrees C has been found to submit to the ideal osmometer law. The membrane impermeability to Mn2+ ions has been disturbed when the temperature falls to -7 degrees C and below, the erythrocytes reaching "the minimal volume".

[Comparative investigation of the dynamic conformational properties of human myeloma immunoglobulin G of different subclasses using impulse NMR]. / Sravnitel'noe issledovanie dinamicheskikh konformationnykh svoistv mielomnykh immunoglobulinov G cheloveka raznykh podklassov impul'snym metodom IaMR.

The evidence of the intramolecular flexibility of human myeloma immunoglobulin G belonging to the second, third and fourth subclasses has been obtained using the impulse NMR method. It has been found that the degree of intramolecular flexibility for the myeloma immunoglobulin G belonging to the first subclass decreases significantly by cooling from 37 to 10 degrees.

[Diffusion of water through the narrow pores of biomembranes]. / Diffuziia vody cherez uzkie pory biomembran.

The pulsed-gradient, nuclear magnetic resonance method has been used to study diffusion of water through the cell membranes. An analytical expression is derived for relative amplitude of nuclear spin-echo, describing the diffusion of water in membrane pores. The latter are so narrow, that their diameter is only a little greater than the water molecule diameter. The experimental data for consumed yeast with normal content of water agree well with the theoretical dependence.