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Biomedical subjects

B V Moskvichev

Publications and source records attributed to B V Moskvichev.

14 recordsLinked to original sources
PubMed1990

Study of the structure of streptokinase conjugates with a hydrophilic vinylpyrrolidone copolymer.

The modification of streptokinase by a synthetic N-vinylpyrrolidone copolymer leads to formation of conjugates varying in structures according to the proportions of the components in the reaction medium. Based on data obtained from spectrophotometry, as well as sedimentation and diffusion analyses, it is shown that in the presence of excess protein in the reaction medium, formation of the main chain takes place via the copolymer associated with several protein globules. Under conditions of excess modifier copolymer, either single-site and/or multiple-site bonding is possible for the protein backbone, depending on the molecular weight of the copolymer. One of the models for the conjugates obtained in this manner has been corroborated by small-angle X-ray scattering data. CD spectral analyses has been performed in order to demonstrate that covalent modification does not alter the secondary structure of streptokinase in the conjugate whereas the tertiary structure undergoes local changes in conformation.

Circular Dichroism↗
PubMed1979

[Kinetics of low molecular weight substrate hydrolysis by immobilized trypsin].

The catalytic properties of trypsin immoblized on silochrome were studied in a flow reactor with replacement. The hydrolysis of methyl ester N-n-tosyl-L-arginine obeys the Michaelis--Menten kinetics. The apparent K'm value for the system with immobilized trypsin is considerably lower than for native trypsin. The K'm value was decreased with an increase in the rate of the substrate flow through the reactor or when smaller-sized silochrome granules were used. It is assumed that the apparent K'm value for the immobilized system is due to diffusion. The effects of diffusion on the catalytic properties of the immobilized enzyme were estimated.

Enzymes, Immobilized↗
PubMed1978

[Some peculiarities of trypsin and heparin interaction].

The interaction of trypsin with an acid polysaccharide, heparin, at pH 4.2 and 8.0 is studied. Heparin is found to destabilize the enzyme under condition of both autolytic denaturation (pH 8.0) and thermoinactivation (pH 4.2). Data on trypsin inactivation kinetics suggest that the stage of forming molecular complexes with different contents of trypsin and heparin precedes the stage of the enzyme denaturation. Maximal trypsin inactivation rate takes place under equimolar enzyme:heparin ration.

Chemical Phenomena↗
PubMed1977

[Some physicochemical properties of modified trypsin].

Physico-chemical properties of trypsin covalently bound with human serum albumin by glutaric aldehyde have been studied. The modification of the enzyme practically caused no changes in the pH optimum of trypsin. The inhibition of modified trypsin by inhibitors from soy beans and human blood serum has been also studied. The apparent inhibition constants have been calculated. The modification has been shown to result in a deceleration of autolytic degradation. The autolysis rate constants have been calculated at 50 degrees C.

Chemical Phenomena↗
PubMedDate not supplied

[Study of ultrafiltration of trypsin solutions].

The dependence of the rate of trypsin ultrafiltration on the concentration, pressure and structure of membranes was studied. During ultrafiltration of diluted trypsin (0.3 mg/ml), water and sodium chloride the flow rate increased linearly with a pressure increase in the range of 0.4-4.2 kg/cm2. During ultrafiltration of trypsin solutions of a concentration of 1 mg/ml and over at a pressure of 2-3 kg/cm2 deviations from linear proportionality occurred which enhanced with an increase in the protein concentration and a decrease in membrane permeability.

Binding Sites↗
PubMedDate not supplied

[Denaturation of the alpha-amylase of Bacillus subtilis in an acid medium].

By fractionation of purine compounds (sorbtion on the cation exchange resin KU-2 (H+), extraction, precipitation of purine compounds as Ag-complexes) a "purine fraction" of the culture liquid epiphytic bacteria No. 703 isolated from barley overground organs was obtained. The presence of isopentenyl cytokinins was demonstrated by quality reactions of the purine fraction with aromatic amines and phenols as well as by the values of Rf and UV spectrum of individual compounds examined by paper chromatography of the purine fraction.

Amylases↗
PubMedDate not supplied

[A study of native streptokinase and its polymeric derivative by means of small angle x-ray scattering].

The gyration radius (R0) of native streptokinase (SK) was found to be R0 = (40 +/- ) A by small-angle X-ray scattering. Experimental hydrodynamic characteristics of SK were S0(20),W = (2.8 +/- 0.1)S; D0(20),W = (6.0 +/- 0.5) x 10(-7) cm2/s; [n] = 0.12 dl/g. The molecular weight of the enzyme was found to be 44,000. The values of the form factor R0/Rsphere = 2.1 and the frictional ratio f/f0 = 1.5 indicate considerable anisometry of the SK molecule. Basing on the curves of small-angle X-ray scattering of SK modified with a synthetic linear copolymer of N-vinylpyrrolidone (P) at a molar ratio SK less than P, a structural model of the conjugate was proposed. The modified form consisted of a dense nucleus covered with a diffuse polymeric membrane. In accordance with the model, R0 of modified SK and of the whole conjugate were found to be R0nucleus = (34 +/- 2) A and R0conjugate = (114 +/- 5)A.

Polymers↗
PubMedDate not supplied

[Chemical modification of proteolytic enzymes by low molecular weight agents].

Low-molecular modification of proteolytic enzymes with aldehydes and anhydrides of carboxylic acids as well as with 2,4,6-trinitrobenzene sulphonic acid was studied. Specific activities of the enzymes were found to be dependent on the modification degree of their amino groups. The retaining of high activities in the region of low extents of enzyme modification enabled biocatalysts with activities similar to those of the native enzymes to be prepared.

Aldehydes↗
PubMedDate not supplied

[Trypsin immobilization on a mineral matrix].

Trypsin immobilization on the mineral matrix--silochrome was studied. The effect of the matrix electrochemical nature on the process was examined. pH-optima for trypsin binding with different silochromes and pH-optimum of action of the immobilized enzyme on casein were determined. The effect on the trypsin-silochrome binding of different supplements--inhibitors (benzamidine), stabilizers (Ca2+) and substrates (casein, benzoyl argininamide hydrochloride) was demonstrated.

Caseins↗
PubMedDate not supplied

[Physico-chemical and enzymatic properties of polymeric trypsin derivatives based on dextran].

The molecular weight distribution, thermal stability during autolysis, resistance to human serum inhibitors as well as temperature optimum of native and dextran-modified trypsin were investigated. The seeming constants of autolytic inactivation and inhibition of native and modified trypsin were calculated. Trypsin polymer derivatives had higher molecular weight than the native enzyme. They also showed higher resistance to autolysis and serum inhibitors. Possible causes of the above effects are discussed.

Autolysis↗