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Biomedical subjects

L V Kozlov

Publications and source records attributed to L V Kozlov.

At least 55 records · Page 3Linked to original sources
PubMed1978

[Effect of soluble matrix on the stability of modified alpha-chymotrypsin].

alpha-Chymotrypsin preparations covalently bound by Shiff bases with water soluble oxidated dextran and alginate are obtained to study the effect of charged and neutral matrices on the enzymes stability under their modification by polymers. Water soluble enzyme preparations show a catalytic activity and have a slightly enhanced thermostability. Thermostability of alpha-chymotrypsin modified by a negatively charged polymer is increased owing to the reducing of activation entropy of the denaturation reaction, while the increase of the stability of neutral polymer (dextran) modified enzyme is due to the increase of activation enthalpy of the denaturation reaction.

Alginates↗
PubMed1977

[Enzymatic properties of immobilized beta-galactosidase from Curvularia inaequalis].

beta-Galactosidase (EC 3.2.1.23) from fungus Curvularia inaequalis was modified by active brilliant orange KH and adsorbed on DEAE-Sephadex A-50. The lactose hydrolysis was studied in a continous flow on the column packed with the immobilized enzyme. The pH and temperatures optima for the substrate hydrolysis by the immobilized enzyme were shown to remain unchanged. A certain destabilizing effect of the matrix on the enzyme resistance to hear denaturation was observed. The activation parameters of denaturation of the native enzyme as well as those of the dye-modified and immobilized preparations were determined.

Chemical Phenomena↗
PubMed1977

[On the changes in alpha-chymotrypsin stability after its modification by polyelectrolytes].

Reversible thermal denaturation of alpha-chymotrypsin, its electrostatic complexes with carboxyl-containing polymers and the enzyme covalently bound with those polymers were studied. It was shown that the enzyme stability is affected by matrix, which manifests itself in a simultaneous decrease in enthalpy and enthropy of the reversible denaturation process and a simultaneous decrease in activation enthalpy and enthropy of denaturation. Modification and complexing of chymotrypsin with polymers has practically no effect on the activation parameters of renaturation. Differences in the original states of alpha-chymotrypsin and its derivatives and similarity of their activated states are proposed. The formation of ionic complexes of enzyme or covalent binding to polymers results in alteration of the protein native state similar to the denaturated state.

Chymotrypsin↗
PubMed1976

Thermal stability of immobilized enzymes circular dichroism, fluorescence and kinetic measurements of alpha-chymotrypsin attached to soluble carriers.

The temperature-induced unfolding of alpha-chymotrypsin and of chymotrypsin covalently bound to two soluble transparent carriers, dextran and a copolymer of maleic acid anhydride and acrylic acid, has been studied by tryptophan fluorescence emission, circular dichroic and kinetic measurements. It has been shown that the structural and functional properties of the enzyme when bound to the anionic copolymer are strongly influenced by electrostatic interactions. A number of reference experiments with anionic polyelectrolytes and the hydrogenated monomers of the copolymer suggest that these changes are brought about by the cooperative ion pair formation between protein and polyanionic matrix.

Acrylates↗
PubMed1976

[Modification and immobilization of beta-galactosidase].

beta-galactosidase from fungus Curvularia inaequalis was modified by a chlortriazin dye active bright-orange KH. The modified enzyme contained two molecules of dye per one molecule of protein. The incorporation of six sulfuric groups with remains of the dye resulted in a slight decrease of the acid protein isoelectric point. The catalytic activity of the modified protein remains practically unchanged. The coloured protein is firmly absorbed on anionites. Preparations of immobilized beta-galactosidase were obtained by adsorption on anionites.

Catalysis↗
PubMedDate not supplied

[The mechanism of inhibition of the activation of the complement first component by polyanions and polycations ].

Polyethyleneimine (PEI, 50 kDa) and polymethacrylic acid (PMA, 200 kDa) were shown to inhibit the lysis of sheep erythrocytes induced by the guinea pig complement. They twofold suppress the hemolysis at the concentrations of 0.47 and 0.89 microgram/ml, respectively. The inhibitory effect on the binding of the C1q subunit of human complement to the sensitized sheep erythrocytes (EA) was found to depend on the component of the reaction with which the inhibitors were preliminarily incubated. When an inhibitor, C1q, and EA were simultaneously incubated, the inhibition constants for PEI and PMA were 17 +/- 6 and 8.1 +/- 0.1 micrograms/ml, respectively. The preincubation of EA with PEI and the subsequent washing out of the inhibitor resulted in the inhibition constant of 22 +/- 3 micrograms/ml. No inhibitory effect was observed after a similar preincubation of EA with PMA. No inhibition was also detected when the inhibitors were added after the formation of the C1q complex with antibodies. These observations suggest that the binding of antibodies to cationic PEI prevents the C1q-antibody complex formation, while the binding of anionic PMA to the active site of C1q impedes the interaction of this subunit with immunoglobulins. Moreover, within the range of concentrations studied, the studied inhibitors did not affect the subsequent C1q binding to the C1r and C1s enzymes.

Animals↗
PubMedDate not supplied

[Physical criteria of pathological processes. III. Structure of the correlation between the level of steady brain potential with serum complement proteins in rheumatic diseases].

The activity of serum complement proteins and the level of steady brain potential in patients with systemic lupus erythematosus and rheumatoid arthritis were determined. The statistical analysis indicated that there is a correlation between the parameters of the complement system and neurophysiological characteristics. The differences between rheumatoid arthritis and systemic lupus erythematosus are observed in the mean values of activity of complement proteins and the steady potential, their dispersions, and the structure of correlations between immunological and neurophysiological parameters.

Arthritis, Rheumatoid↗
PubMedDate not supplied

[Inborn deficiency of complement C4A and C4B isotypes in persons infected with Chlamydia].

The difference in the functional activity of the isotypes A and B of component C4 of human complement was used to determine their ratio to detect the inherited deficiency of the isotypes. The frequency of deficiency in healthy persons blood donors was equal for C4A and C4B (0.14 for each isotype), i.e. 14% of total number (22) donors, or 28% totally. These results agree with the literary data, on which the frequency of deficiency of C4A is 0.14, and of C4B is 0.11-0.16. The inherent deficiencies of C4A and C4B for persons infected by Chlamydia were studied. For this purpose the patients (35 persons) with in blood antibodies (IgG or IgM) to Chlamydia (C. trachomatis, C. psittaci and C. pneumoniae) were investigated. The frequencies of deficiency of C4A and C4B were 0.29 and 0.46 respectively. Thus, the number of the undeficiency patients was only 25%, while among healthy persons 70-75% of individuals not having deficiencies of isotypes C4 were observed. The deficiencies of isotypes of C4 at this pathology is detected for the first time. The obtained data suggest the existence of the predisposition to the development of diseases stipulated by Chlamydia in persons with inherent deficiency of C4 component of complement.

Adult↗
PubMedDate not supplied

[A drop of mink complement kills a mouse].

The phenomenon of fast death of mice after parenteral administration of mink serum was explained by high activity of mink complement in particular by unusually high activity of its alternative pathway of activation. The presence of antibodies to mouse erythrocytes in mink serum was necessary precondition for their lysis under action of mink complement by classical and alternative pathways. However, removal of these antibodies resulting in cancellation of hemolysis did not effect toxicity of mink serum for nice in vivo. Partial decomplementization of mink serum zymosan completely prevented death of animals.

Animals↗