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A M Egorov

Publications and source records attributed to A M Egorov.

At least 109 records · Page 6Linked to original sources
PubMed1985

[Use of immunoenzyme analysis for controlling the activity of antisera to insulin].

Antisera to insulin were obtained from guinea pigs hyperimmunized with the use of Freund's adjuvant. To control the specific activity of antisera, the highly specific modern method of ELISA was used. Insulin was allowed to adsorb on the surface of the wells of polystyrene microplates, then consecutive dilutions of the tested antisera to insulin were placed into the wells. The insulin-antibody complexes thus obtained were detected by means of immunoperoxidase conjugate. Antibody titers in antisera obtained from different animals varied from 5 X 10(-3) to 10(-5). A good correlation between the results obtained by ELISA and by radioimmunoassay was observed.

Animals↗
PubMed1983

[Chemical modification of the lysine residues of bacterial formate dehydrogenase].

Inactivation of formate dehydrogenase by formaldehyde, pyridoxal and pyridoxal phosphate was studied. The effects of concentrations of the modifying agents, substrates, products and inhibitors on the extent of the enzyme inactivation were examined. A complete formate dehydrogenase inactivation by pyridoxal, pyridoxal, phosphate and formaldehyde is achieved by the blocking of 2, 5 and 13 lysine residues per enzyme subunit, respectively. The coenzymes do not protect formate dehydrogenase against inactivation. In the case of modification by pyridoxal and pyridoxal phosphate a complete maintenance of the enzyme activity and specific protection of one lysine residue per enzyme subunit is observed during formation of a binary formate-enzyme complex, or a ternary enzyme--NAD--azide complex. One lysine residue is supposed to be located at the formate-binding site of the formate dehydrogenase active center.

Alcaligenes↗
PubMed1983

[Bacterial formate dehydrogenase. Substrate specificity and kinetic mechanism of S-formyl glutathione oxidation].

The substrate specificity of NAD-dependent formate dehydrogenase from the methylotrophic bacterium Achromobacter parvulus T1 was studied. The kinetic mechanism of S-formyl glutathione oxidation was determined. The initial velocity studies and inhibition analysis were carried out. It was shown that the kinetic mechanism for the enzyme with S-formyl glutathione as a substrate is similar to that with formate and is rapid-equilibrium random. Using independent methods, it was found that formate dehydrogenase forms a binary complex with S-formyl glutathione (Kd = 2.5 mM).

Alcaligenes↗
PubMed1982

Chemical modification of lysine residues in bacterial formate dehydrogenase.

Specific modification of 4.4 lysine residues per molecule of formate dehydrogenase, from the methylotrophic bacterium Achromobacter parvulus I by pyridoxal, results in complete inactivation of the enzyme. The concentration effect of the modifying agent and substrates on the inactivation of formate dehydrogenase has been studied. Coenzymes do not protect the enzyme from inactivation. Complete maintenance of enzyme activity was achieved in the presence of saturating concentrations of the formate and upon formation of the ternary complex, enzyme-NAD-azide. Formate specifically protects two lysine residues per dimer molecule of the enzyme from modification. The presence of one essential lysine residue in the substrate-binding region of the enzyme active site is assumed.

Alcaligenes↗
PubMed1982

[Kinetics of NAD-dependent formate dehydrogenase from the methanol-utilizing yeast Candida methylica].

A kinetic analysis of the mechanism of action of NAD-dependent formate dehydrogenase (EC 1.2.1.2) from the methanol-utilizing yeast Candida methylica has been carried out. The dependence of the initial reaction rate on substrate concentrations and the inhibition by the reaction products and substrate analogs were investigated. The data obtained suggest that the kinetics of the formate dehydrogenase action are consistent with the formation of a ternary enzyme--substrate complex. NAD is the first substrate and NADH is the last product of the reaction, respectively.

Aldehyde Oxidoreductases↗
PubMed1981

Study of the role of arginine residues in bacterial formate dehydrogenase.

Modification of 12 arginine residues per molecule of formate dehydrogenase (formate : NAD+ oxidoreductase, EC 1.2.1.2.) from the methylotrophic bacterium, Achromobacter parvulus I, by 2,3-butanedione results in complete inactivation of the enzyme. Inactivation of the enzyme is reversible and proceeds in two steps via formation of the intermediate enzyme-butanedione complex. Coenzymes but not formate effectively protect formate dehydrogenase from inactivation. Complete maintenance of enzyme activity and specific protection of one arginine residue per enzyme subunit are achieved on formation of the binary complex, enzyme-NAD, or the ternary complex, enzyme-NAD-azide. One arginine residue is supposed to be located at the NAD-binding site of the formate dehydrogenase active centre.

Alcaligenes↗
PubMed1981

[ATP-insulin conjugates and their use for immunofactor analysis].

A method resulting in ATP-insulin conjugates by covalent binding of ATP modified at C(6) amino group of the adenine residue with insulin was developed. The modified ATP was bound to insulin by means of metha-p-toluene sulfonate-N-cyclohezyl Nf [2-morpholinyl(4)ethyl]-carbodiimide. The ATP analogs and ATP-insulin conjugates possess the coenzyme activity in a reaction of luciferin oxidation by luciferase from the fireflies Luciola mingrelica. the catalytic properties of soluble and immobilize on CNBR-activated. Sepharose enzymes in reactions with native ATR, its modified derivatives and ATP--insulin conjugates were compared. The bioluminescence reaction involving ATP--insulin conjugate is inhibited by antibodies against insulin. This effect can form a basis for insulin detection in solution, which is based on competitive binding of free and antibody-labelled ATP--insulin conjugates.

Adenosine Triphosphate↗
PubMed1981

[Kinetics of the NADH regenerating system using bacterial formate dehydrogenase].

The main kinetic regularities of the NADH regeneration system functioning was studied. A theoretical interpretation of the dependence of the stationary reaction rate in a two-enzyme system with a common cofactor on the enzyme, cofactor and substrate concentrations and the catalytic parameters of individual enzymatic processes was obtained. A mathematical analysis of the dependences of the stationary rate on the content of each enzyme in the system at different activity ratios of each enzyme and within a broad range of initial cofactor concentrations was carried out. The kinetics of regeneration of native NADH and the NADH immobilized on a water-soluble 4-vinylpyridine and acroleine copolymer in a model two-enzyme formate dehydrogenase--NADH dehydrogenase system were investigated.

Alcaligenes↗
PubMed1981

[Isolation and properties of NAD-dependent formate dehydrogenase from the yeast Candida methylica].

NAD-dependent formate dehydrogenase was purified from a cell-free extract of methanol-consuming yeast Candida methylica, using chromatography on DEAE-cellulose and gel-filtration on Sephadex G-200. The enzyme is electrophoretically homogeneous, consists of two identical subunits with molecular weight of 46,000 and is active within the pH range of 6-9; the Km values for NAD and formate are 1 . 10(-4) and 1,3 . 10(-2) M, respectively. Formate dehydrogenase is inhibited by p-chloromercurybenzoate, iodoacetate, dithionitrobenzoate and azide.

Aldehyde Oxidoreductases↗
PubMed1980

[Inhibition of glucose isomerase from Actinomyces olivocinereus 154 by polyols].

The inhibitory action of polyols, e. g. D-mannitol, D-glucitol, ribitol and xylitol, on the activity of glucose isomerase prepared from Actinomyces olivocinereus 154 was studied. All the polyols under study are purely reversible competitive inhibitors. The values of Ki for D-mannitol, D-sorbitol, D-arabitol, D-glucitol, ribitol and xylitol are 0.200, 0.140, 0.030, 0.024 and 0.020 M, respectively. The inhibition is to some extent decreased by increasing concentrations of the substrate and is completely abolished by increasing concentrations of Mg2+ and Co2+--up to 5.10(-2) and 5.10(-3) M, respectively.

Actinomyces↗
PubMed1980

[Role of sulfhydryl groups in the inactivation mechanism of bacterial formate dehydrogenase].

Inactivation of formate dehydrogenase (EC 1.2.1.2) from gramnegative methanol-utilizing bacteria was studied. It was shown that the thermal inactivation of the enzyme occurs at temperatures above 50 degrees; at temperatures below 40 degrees the inactivation is due to metal ion-catalyzed oxidation of its sulfhydryl groups. A possible general mechanism of the enzyme inactivation is proposed.

Aldehyde Oxidoreductases↗
PubMed1980

[Role of amino acid arginine residues of bacterial formate dehydrogenase].

Inactivation of NAD-dependent formate dehydrogenase by butandione-2,3 has been studied. The inactivation is shown to be due to specific modification of the arginine residues. The enzyme activity is completely abolished by modification of 17 arginine residues per enzyme molecule. Native formate dehydrogenase contains 50 arginine residues. The dependences of the enzyme inactivation rate on butandione and substrate concentrations and the pH profile of the inactivation have been investigated. Coenzymes (but not formate) protect the enzyme against inactivation. The enzyme activity is completely retained upon formation of a binary E-NAD complex and a ternary E-NAD-azide complex. Protection of one arginine residue per enzyme subunit is observed under formation of a ternary enzyme--inhibitor complex. The fole of the arginine residue in coenzyme binding is discussed.

Aldehyde Oxidoreductases↗