[Self-association and secondary structure of beta-casein].

The secondary structure alterations, accompanying isothermal and temperature guided beta-casein micellization have been studied by dynamic light scattering, circular dichroism and Fourier transform infrared spectroscopy techniques. Micelle formation induced by increase of protein concentration at constant temperature is accompanied by the formation of scanty number of additional peptide hydrogen bonds, preliminary assigned to intraprotein beta-structure. Heating results in more pronounced but qualitatively different changes consisted in dehydration of peptide groups and disruption of polyproline II helix segments with subsequent conversion to random and beta-turns. Nevertheless, in both cases the total number of residues involved in transition is quite few and cannot be regarded as a decisive factor for casein micellization.

[Influence of dioxane on the hydration shell of polypeptides].

Our interest in modifying influence of the low-molecular organic compounds on the hydration shell of biopolymers is due to a well-known fact that the former can act as regulators of the enzymatic activity changed the hydration shell of the latter. Dioxane was chosen because of its wide application in non-aqueous biocatalysis. In the present study we investigate the mechanisms of the dioxane influence on water of the first hydration layer of the model polypeptides by FTIR-spectroscopy during simultaneous sorption of water-dioxane vapors into the polypeptide films at low water activity. It was found that modification of the hydration shell of the studied polypeptides was mainly due to the indirect ordering ofpolypeptide secondary structure at penetration of dioxane molecules at these conditions.

[Chaperone-like activity of beta-casein and thermal stability of alcohol dehydrogenase].

To elucidate the correlation of structural peculiarities of beta-casein and their chaperon-like activity the modified forms of the protein (with cysteinyl residues introduced in polypeptide chain) were investigated. The aggregation of native and recombinant beta-caseins was studied as well as their chaperon-like activity towards alcohol dehydrogenase thermal aggregation. It was shown that physico-chemical and chaperone-like properties ofdimeric and oligomeric forms ofbeta-casein (which formation is due to intermolecular disulfide bonds) differ significantly from monomeric forms. It was found that thermal stability of alcohol dehydrogenase depends on beta-casein concentration.

[Effect of the interphase surface charge on the structure and activity of trypsin in inverted micelles].

The effect of the sign and value of the charge of the interphase surface on the catalytic activity of trypsin in systems of inverted mycelles was investigated. n-Butanol was used for the modification of the phase interface in dispersions of inverted mycelles based on anionic sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and cationic cetyltrimethylammonium bromide (CTAB). A direct correlation between changes in the state of inverted mycelles and the structure of solubilized enzyme under the action of butanol was obtained. It was shown that the enzyme activity is determined by the quantity of butanol solubilized by the inverted mycelles.

[Effect of trypsin microenvironment on the rate constants of elementary stages of Nalpha-benzoyl-L-arginine ethyl ester hydrolysis].

The hydrolysis reaction of Nalpha-benzoyl-L-arginine ethyl ester catalyzed by trypsin from pig pancreas was comparatively studied in an aqueous buffer solution and in the system of reversed micelles of Aerosol OT in octane (pH 8.5) to determine the mechanisms of influence of the enzyme microenvironment on the rate constants of the elementary stages of the enzymatic reaction. The temperature dependences of the catalytic constant kcat and the rate constant of the second order kcat/Km (s, catalysis efficiency) allowed the determination of the rate constants and the activation energy of elementary stages of the enzymatic reaction. It was revealed that a decrease in the efficiency of catalytic action of trypsin in inverted mycelles in comparison with an aqueous solution is first of all determined by a decrease in the rate constant of formation of the enzyme-substrate complex k1. Possible mechanisms of the effect of the microenvironment on the elementary stages of catalytic action of the enzyme are discussed.

[Study of the connection of the resistance of the lung to the development of pathologic processes with its fatty acid composition]. / Issledovanie sviazi rezistentnosti legkogo k razvitiiu patologicheskikprotsessov s ego zhirnokislotnym sostavom.

Selective localization of unspecific pathological processes was detected in lung lobes of 1244 patients, whereas irregular fatty acid composition of phospholipids was observed in the tissue lobes of 23 patients. The correlation curve, reflecting the fatty acid spectrum dependent development of impairments in lungs, was plotted and risk factors were calculated for various groups of persons with various fatty acid spectra in lungs.