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Biomedical subjects

A M Egorov

Publications and source records attributed to A M Egorov.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

[New strain of methylotrophic bacteria Pseudomonas oleovorans--a polysaccharide producer].

A new strain of facultative-methylotrophic bacteria was isolated and identified as Pseudomonas oleovorans. The culture grew on the methanol-containing medium (up to 6%). In addition to methanol, bacterial growth was provided by different organic acids, multicarbon alcohols and carbohydrates. During growth bacteria synthesized extracellular polysaccharide (up to 400 mg/ml). The compound included glucose, galactose and xylose.

Alcohols↗
PubMedDate not supplied

[Synthesis of conjugates of L-lysine alpha-oxidase with antibodies].

The conjugation of the drugs with vector molecules enables to obtain therapeutic preparation, which may be transported to the selected target organ. In the present work the methods of conjugation of antineoplastic enzyme L-lysine alpha-oxidase with antibodies were elaborated. Conjugates were worked out through the attachment of amino groups on the antibody surface either with the aldehyde groups which were created in L-lysine alpha-oxidase molecule (0.2% of initial enzymatic activity) or with the aldehyde groups of cross-linking molecules. Maximal (78%) L-lysine alpha-oxidase activity in conjugates was observed when oxidized peroxidase which contained the aldehyde groups was used as crosslinking agent. The glutaraldehyde method yielded 70% of initial enzyme activity.

Animals↗
PubMedDate not supplied

[Analysis of the model binding site of anti-2,4-dichlophenoxyacetic acid antibodies].

Models of three-dimensional structures of Fv domains of three antibodies specific to the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) have been derived from the sequence data by comparative modeling. The same binding site cavities were observed in all cases. The most important residue in antigen binding is tyrosine, which serves as a wall of cavity and putatively forms pi-stacking interaction with aromatic moiety of the ligand. Another cavity wall is formed by hydrophobic residues. At the entrance of cavity a glutamate residue is located in 2 of 3 structures. Docking of 2,4-D and its analogs on the models was performed. On the basis of docking results an experimental cross-reactivity data were qualitatively explained. Using results of the modeling, mutation of glutamate to serine or lysine was suggested to eliminate electrostatic repulsion between antibody and ligand and to improve 2,4-D binding efficiency. Target mutations in the antibody binding site were checked on the model.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

[Enzyme immunoassay of ampicillin in milk].

An indirect immunoassay for quantitative determination of ampicillin (range, 10-1000 ng/ml) in buffer or milk has been developed. Polyclonal antibodies were obtained against ampicillin conjugated with bovine serum albumin; the conjugate was synthesized by direct condensation using carbodiimide. The antibodies were specific for ampicillin and exhibited low cross-reactivity to other penicillins (azlocillin, 17%; penicillin G, 10%; piperacillin, 5%; and carbenicillin, 4%). Matrix effects were minimized by combining the use of a casein-supplemented buffer (content of casein, 1%) with sample dilution. The threshold of ampicillin detection in milk (diluted tenfold) was equal to 5.0 ng/ml (which corresponded to 50 ng/ml of the original sample).

Ampicillin↗
PubMedDate not supplied

[Immobilization of nicotine amide adenine dinucleotide derivatives and their function as cofactors of bacterial formic dehydrogenase].

NAD+ was modified with respect to the C(6)-amino group of the adenine residue by iod acetic acid alkylation in N1-position and subsequent rearrangement into N6-position. By condensation of N6-carboxy methyl-NAD+ with 1,6-diamino hexane, N6-[(6-aminohexyl)-acetamide]-NAD+ was synthesized. This process was controlled spectrophotometrically and by analytical isotachophoresis. NAD+ derivatives were found to maintain high co-enzymic activity in the reaction of formic oxidation with formic dehydrogenase from gram-negative methylotrophic bacteria, str. 1. Kinetic parameters of the reaction involving the resultant components were determined. NAD+N6-derivatives were covalently bound with the water insoluble carrier--Sepharose 4B and water soluble carriers--acrolein and 4-vinyl pyridine copolymers and dextran. The rates of formic dehydrogenase reduction of the native and immobilized cofactors were compared.

Aldehyde Oxidoreductases↗
PubMedDate not supplied

[Beta-galactosidase from E. coli as a marker in immunoenzyme analysis].

In the present review the authors analyze factors influencing sensitivity of the enzyme immunoassay (EIA). beta-Galactosidase from E. coli was chosen as a marker enzyme. Physico-chemical properties of the enzyme, detection methods and various ways of obtaining chemical conjugates with antigens and antibodies are discussed. Some examples of using beta-galactosidase as a label in homogeneous and heterogeneous EIA are given which enables different compounds to be analyzed with a high sensitivity. New approaches employing gene engineering for constructing "fusions" between beta-galactosidase and antigens (alternative to chemical conjugates) are discussed that can be used in the near future.

Escherichia coli↗
PubMedDate not supplied

[Quantitative determination of immunoglobulin A in human serum by an immunoenzyme technic].

A complex of immunoglobulin A (IgA) with peroxidase was obtained as a result of interaction of IgA with the enzyme, modified with sodium periodate. The molar ratio of IgA/peroxidase was equal to 1 in the complex, as shown by gelfiltration and sedimentation analysis. Peroxidase maintained 75% of the initial activity in the complex. The antigenic and enzymatic properties of the complex were retained completely within 5 months, if the preparation was kept at 4 degrees in phosphate buffer, pH 7.4. The complex isolated was used for quantitative estimation of IgA in human blood serum. The method is based on the reaction of competitive binding between free and labelled with peroxidase IgA molecules and antibodies, immobilized on inorganic porous carrier--sylochome. The method enables to estimate quantitatively IgA concentration within the limits of 102=105 ng/ml.

Chromatography, Gel↗
PubMedDate not supplied

[Amperometric sensor for recording the results of immunoenzyme analysis].

A technique for quantitative determining horseradish peroxidase was developed using an amperometric sensor that makes it possible to register up to 50 pM of the enzyme in the reaction of the peroxidase oxidation of iodide ions by hydrogen peroxide. The sensor, composed of combined carbon and Ag/AgCl electrodes, is intended for enzyme immunoassay and may be used for registering the results in the very wells of the polystyrene plates widely used in clinics and laboratories. The dependences of the initial rate of the enzymatic reaction on the substrate concentration and pH of the medium were determined, on the basis of which the conditions for the optimal operation of the sensor were found. The amperometric and spectrophotometric methods of registration on a model system for determining antibodies against X-virus of potato were compared in order to show a possibility of the sensor applying to enzyme immunoassay.

Electrochemistry↗
PubMedDate not supplied

[The Homogeneous immunocofactor method of determining insulin].

An immunocofactor quantitative method of measuring insulin in solution was developed. The method uses antibody competitive binding of free and NAD labeled insulin. The NAD-insulin conjugate was obtained by covalent binding of the C(6)-aminogroup modified cofactor with insulin by means of soluble carbodiimide. To determine the NAD-insulin conjugate, which was not bound with antibodies, in the presence of antibodies and free insulin, an enzymic system of the cofactor regeneration with conjugated substrates of horse liver alcohol dehydrogenase, cyclohexanol and p-nitroso-N,N-dimethyl aniline, was employed. The sensitivity of insulin assay was about 5.10(-7) M.

Animals↗
PubMedDate not supplied

[Comparison of luciferase activity of homogenates from fireflies of different species].

The stability and catalytic properties of enzymes from fireflies of three species - Lucida mingrelica, Lucida mongolica and Lampris sp.-were investigated. The enzyme of the homogenate from Lampris sp. was found most stable. The enzyme specific activities of the three species differed greatly. The specific activity of the homogenate from Luciola mingrelica was 7 times higher than that from Lampris sp. The Km constants with respect to Mo ATP and luciferine were identified for each enzyme.

Animals↗