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Biomedical subjects

A M Egorov

Publications and source records attributed to A M Egorov.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Preparation of immunoenzyme conjugates of beta-lactamase from Bacillus licheniformis 749/c and horseradish peroxidase with human antibodies to HIV-1].

By using three different linkage methods with carbodiimide, glutaraldehyde and periodite, immunoenzyme conjugates of beta-lactamase from Bacillus licheniformis 749/c and horse radish peroxidase with human antibodies to HIV-1 were prepared. The human antibodies were purified by the affinity procedure on Protein-A-Sepharose 6B. The conjugates were tested in a solid phase immunoenzymatic system for the HIV-1 antigen. It was shown that the conjugates prepared by the carbodiimide linkage method had the highest titer, the beta-lactamase conjugate being superior by its titer to the respective peroxidase conjugate. In the lyophilized state the conjugates prepared with the carbodiimide linkage method were stable.

Bacillus↗
PubMed1991

[Biliodigestive anastomoses using mechanical sutures].

The authors provide information concerning an experimental model of a suturing instrument for the formation of linear biliodigestive anastomoses, by means off which the communications are created in different parts of the ducts, even the intrahepatic ducts, 5 mm or more in diameter. The instrument was used in operations on 29 patients who had cicatricial stenosis of the major duodenal papilla, carcinoma of the pancreas or ducts in the region of the porta hepatis. The instrument is universal in range and can be used for the creation of various types of biliodigestive anastomoses, it makes the operative techniques simpler and more reliable. Complications associated with the use of the instrument did not occur.

Aged↗
PubMed1991

[Interaction of monoclonal antibodies with horseradish peroxidase].

Properties of four types of monoclonal antibodies to horse-radish peroxidase were investigated. The dissociation constants and molecular-weight composition of the immune complexes were determined. The antibodies are shown to be directed to different epitopes on the polypeptide chain. Results of the theoretical prediction of the epitope localisation are presented. The interaction between the antibodies and peroxidase isozymes were studied.

Amino Acid Sequence↗
PubMed1990

Evaluation of dissociation constants of antigen-antibody complexes by ELISA.

In this communication some of the advantages and constraints in the use of ELISA (enzyme-linked immunosorbent assay) procedures to evaluate antigen-antibody dissociation constants (Kd) are discussed and experimental conditions under which the effective Kd is close to the true value are proposed. Interactions between horseradish peroxidase (POD), human myoglobin and insulin with mono- and polyclonal antibodies (McAb and PcAb) were used to demonstrate that ELISA can be used to determine the average Kd, characterizing the interaction between antigens and PcAb. The Kd values obtained by ELISA were similar to those determined by luminescent immuno-cofactor analysis (LICA).

Animals↗
PubMed1990

The solvent effects on the kinetics of bacterial formate dehydrogenase reaction.

The increase in concentration of organic cosolvents results in a 2-2.5-fold increase of the maximal reaction rate and a decrease of Michaelis constant for formate of NAD(+)-dependent formate dehydrogenase from methylotrophic bacteria Pseudomonas sp. 101. These parameters, however, are not affected with the increase of ionic strength. For the logarithm of both Vmax and Km a linear function of the reciprocal of solvent dielectric permittivity was found. The decrease of Km is possibly due to the dielectric screening effect on the substrate binding energy. The increase in Vmax is explained by a model based on a solvent-dependent electrostatic image force, acting on the charges moved in the course of the catalytic step of the enzyme reaction.

Alcohols↗
PubMed1990

[Immunoenzyme analysis of insulin antibodies in human blood serum].

Indirect solid-phase enzyme immunoassay (EIA) was used for the titration of antibodies to insulin in human blood sera. The modification suggested by the authors permits assessing the immunoglobulins G and M insulin-binding ability. The technique was optimized for all the stages of analysis and a method for estimating the insulin-binding ability of IgG in the sera diluted 1:80 and of IgM in the sera diluted 1:320 was developed. Fifty blood sera of patients with insulin-dependent diabetes mellitus were analyzed. EIA results were in good correlation with the findings of radioimmunoassay.

Diabetes Mellitus, Type 1↗
PubMed1990

[Determination of the sorption properties of microplates for immunoenzyme analysis].

The authors have examined the possibility of using horse radish peroxidase for assessment of the sorption characteristics of microplates for enzyme immunoassay; the results obtained by the technique modified by the authors and by one of the routine methods (the direct method) were in high correlation. Sorption capacities and homogeneity of the plates manufactured in Leningrad and abroad were compared; the plates made in this country were found inferior to foreign ones in respect of both parameters almost twofold. Sorption capacity of the microplates may be improved by gamma-irradiation; the optimal irradiation dose was defined: 1.5 mrad.

Adsorption↗
PubMed1990

[Study and immunoanalytical applications for peroxidase from Arthromyces ramosus].

Some biochemical and catalytic properties of peroxidase from Arthromyces ramosus (EC 1.11.7.1) in chemiluminescent reaction of luminol oxidation by hydrogen peroxide were investigated. The second order rate constants were determined by the stopped-flow technique. Optimal conditions to quantity the enzyme were found, the detection limit being 5.10(-13) M. The peroxidase was used as a marker in the human IgG immunoassay.

Catalysis↗
PubMed1990

[The effect of condition of oxidation of the carbohydrate component of peroxidase on the composition and properties of insulin-peroxidase conjugate].

The influence of sodium metaperiodate concentration on kinetics and conversion degree of peroxidase carbohydrate moiety as well as the effect of the oxidation degree of the carbohydrate moiety on the composition, structure and properties of insulin-peroxidase conjugates were studied. The initial rate of peroxidase's oxidation is directly proportional to the periodate concentration; the oxidation rate constant of peroxidase carbohydrate moiety is 1.23 x 10(-3) M-1 min-1. At the molar ratio of metaperiodate to peroxidase 150:1 or higher, the maximal quantity of aldehyde groups (62 +/- 2) in the peroxidase molecule is formed and the oxidation of each carbohydrate chain leads to the formation of eight aldehyde groups. The molecular mass composition of the insulin-peroxidase conjugates was studied by HPLC. The conjugates proved to be multicomponent mixtures of oligomers (53, 83, 128, 174, 268, 440 kD and higher). The insulin-peroxidase molar ratio in the fractions of the conjugates with molecular masses higher than 83 kD is 8:1. It was shown that the affinity of insulin-peroxidase conjugates to antibodies depends on the oxidation degree of peroxidase used for production of conjugates.

Carbohydrate Metabolism↗
PubMed1989

Evidence for the presence of a new NAD+-dependent formate dehydrogenase in Pseudomonas sp. 101 cells grown on a molybdenum-containing medium.

The facultatively methylotrophic bacterium Pseudomonas sp. 101, grown on methanol in presence of molybdate, contains a new formate dehydrogenase (N-FDH) catalyzing NAD+-dependent oxidation of formate. The activity of this N-FDH could also be measured in presence of artificial electron acceptors, ferricyanide and 2,6-dichlorophenol indophenol. This new enzyme is absent in cells grown on a methanol-containing medium with tungstate, where only another two, previously described formate dehydrogenases, which are active only with NAD+ or only with artificial acceptors, respectively, were determined. The N-FDH was partially purified by a combination of ion-exchange and gel-filtration chromatography, and was shown to differ in its properties from the known NAD+-dependent counterpart.

Aldehyde Oxidoreductases↗
PubMed1989

Kinetic isotope effect and the presteady-state kinetics of the reaction catalyzed by the bacterial formate dehydrogenase.

The primary kinetic isotope effect of the reaction catalyzed by NAD+-dependent formate dehydrogenase (EC 1.2.1.2.) from the methylotrophic bacterium Pseudomonas sp. 101 has been studied. Analysis of the ratios HVm/DVm and H(Vm/KM)/D(Vm/KM) in the pH range 6.1-7.9 showed that the transfer of hydride ion in ternary enzyme-substrate complex is a limiting step of the reaction, and the formate binding to the binary complex (formate dehydrogenase + NAD+) reached equilibrium when the pH of the medium was increased. An approach has been developed to determine the elementary constants of substrate association (kon) and dissociation (koff) at the stages of the binary--ternary enzyme-substrate complexes for the random equilibrium 2-substrate kinetic mechanism. The kon and koff values obtained for the bacterial formate dehydrogenase by using the proposed approach for NAD+ were (4.8 +/- 0.8)*10(5)M-1s-1 and (90 +/- 10) s-1, and for formate (2.0 +/- 1.0)*10(4) M-1s-1 and (60 +/- 20) s-1, respectively.

Aldehyde Oxidoreductases↗
PubMed1987

NAD-dependent hydrogenase from Alcaligenes eutrophus Z1: does it have a regulatory centre?

Evidence is presented for the existence of a relatively high-potential regulatory centre in the NAD-dependent hydrogenase from the hydrogen oxidizing bacterium Alcaligenes eutrophus Z1. Reduction of the hydrogenase to the redox potentials lower than -100 mV converts the enzyme into a catalytically active state that is remarkably stable to oxidants. Once activated, the enzyme does not loose its activity on intensive oxygenation for at least 3 hours. A novel hydrogenase ESR signal with a wide temperature optimum and a approximately -100 mV midpoint redox potential was detected. We suggest that the reduction of this redox centre trigger conformational changes in the inactive oxidized enzyme molecule, thus reorganizing the latter into the active one.

Alcaligenes↗