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Biomedical subjects

V P Varlamov

Publications and source records attributed to V P Varlamov.

At least 19 recordsLinked to original sources
PubMed2005

Ultrastructural study of chitosan effects on Klebsiella and staphylococci.

Antibacterial effect of chitosan on the morphofunctional organization of clinical strains of Klebsiella pneumoniae and Staphylococcus aureus was studied by transmission electron microscopy. Chitosan promoted aggregation of bacterial cells and disorganization of bacterial cell wall and cytoplasmic membrane, which leads to the release of bacterial contents into the environment. These structural changes result in bacterial death.

Bacterial Capsules↗
PubMed2004

Bionanocompositional chitosan-silica sorbent for liquid chromatography.

Preparation of hybrid nanocompositional chitosan/silica sorbent was carried out. It was shown that formation of gel in sol-gel process of hydrolytic polycondensation of tetraethoxysilane (TEOS) with including of chitosan consists of two stages. Suppression of crystallization of chitosan in obtained two-phase system and changes in IR spectra are evidenced of interactions between molecules of chitosan and silanol groups of silica network. The resulting hybrid chitosan/silica sorbent was tested by high-performance liquid chromatography (HPLC).

2-Propanol↗
PubMed1998

Isolation of thermostable phosphatase from the hyperthermophilic archaeon Thermococcus pacificus by immobilized metal affinity chromatography.

Phosphatase was isolated from cells of the hyperthermophilic marine archaeon Thermococcus pacificus by a procedure including chromatography on Butyl-Fractogel TSK-650 and Ni(2+)-iminodiacetic-agarose. Enzyme activity is maximal at 90 degrees C, and the enzyme half-life time at this temperature is 1 h. The pH optimum of phosphatase activity is 6.0. Electrophoresis under denaturating conditions yielded a subunit molecular weight of 45 kDa. On gel-filtration on Sephacryl S-300 HR three peak corresponding to 295, 85 and 45 kDa were observed, suggesting that the enzyme is a homohexamer.

Cations, Divalent↗
PubMed1995

New approaches to chromatographic purification of bovine dopamine-beta-hydroxylase.

The use of the traditional scheme for the isolation of bovine dopamine-beta-hydroxylase (bDBH) from bovine adrenal medulla resulted in active but not pure bDBH, containing about 50% of admixtures. Immobilized metal chelate affinity chromatography on agarose modified with iminodiacetic acid residues and charged with cobalt ions was applied in the final stage to obtain more than 90% pure and active bDBH. Final purification of bDBH using step elution with 0-0.5 M methyl-D-mannoside in buffer solution from concanavalin A-Sepharose was studied. The determination of bDBH in various samples was performed using size-exclusion chromatography.

Adrenal Medulla↗
PubMed1995

Mass-spectrometric analysis of N-acetylchitooligosaccharides prepared through enzymatic hydrolysis of chitosan.

A semipreparative scale chromatography of N-acetylchitooligosaccharides (GlcNac)2-7 on a reversed-phase C-16 HPLC column is reported. The initial material was obtained by enzymatic hydrolysis of chitosan with a complex of chitinases from Streptomyces kurssanovii, followed by a complete acetylation of amino groups. Isolated N-acetylchitooligosaccharides were characterized by the mass-spectrometric method. On interacting with the sample, the fragments of 252Cf caused desorption of quasi-molecular ions of the substance. All mass spectra of chitin oligomers contained intense quasi-molecular ions [M + Na]+ and a less intense [M + K]+ ion. Fragment ions, compared to the quasi-molecular ion [M + K]+, had a lower intensity and confirmed the structure of samples under study. Due to this phenomenon, an accurate analysis of both individual compounds and mixtures of N-acetylchitooligosaccharides (n = 2-7) may be performed.

Acetylation↗
PubMed1995

Preparation of affinity sorbents and isolation of individual chitinases from a crude supernatant produced by Streptomyces kurssanovii by a one-step affinity-chromatographic system.

The preparation of two affinity-chromatography sorbents based on cross-linked chitin are described. Both sorbents retained selectively one of the four extracellular chitinases in the culture supernatant produced by Streptomyces kurssanovii. Chitinases with molecular masses of 42 kDa and 26 kDa were isolated in homogeneous form using one-step affinity-chromatography procedures involving either a fully N-acetylated or a partially N-acetylated cross-linked chitin-type sorbent. Two other chitinases were not selectively bound by the sorbents and, therefore, were not isolated in a homogeneous form. The affinity sorbents were shown to be stable over the period of separation and could be used repeatedly.

Anticholesteremic Agents↗
PubMed1994

[New acetylcholinesterase inhibitors--derivatives of vitamin B6].

A new approach to design of reversible inhibitors of acetylcholinesterase (ACHE)--derivatives of natural compounds--has been worked out, as exemplified by vitamins of the B6 group. Analysis of the data obtained revealed main structural elements of the 3-hydroxypyridine molecule related to the inhibitory properties. Pyridoxamine derivatives are of interest in constructing new potent inhibitors of ACHE.

Acetylcholinesterase↗
PubMed1994

One-step isolation of a chitinase by affinity chromatography of the chitinolytic enzyme complex produced by Streptomyces kurssanovii.

One of the four chitinases with a molecular mass of 42 kDa existing in the chitinolytic enzyme complex produced by Streptomyces kurssanovii was separated in homogeneous form using one-step affinity chromatography on cross-linked and phosphorylated chitin-type sorbents. Three other chitinases were not selectively bound by the sorbents and were not obtained in homogeneous form. The affinity sorbents were shown to be stable over the time of separation and could be used repeatedly.

Adsorption↗
PubMed1992

[The antiviral action of a modified bacterial ribonuclease].

The antiviral activity of a bacterial ribonuclease conjugate with chitosane of Kamchatka crab (in a form of water soluble chito-oligosaccharides) has been studied. The conjugate inhibitory activity for A and B viruses as well as to Sindbis arbovirus in tissue cultures is shown. The preparation efficiency at intramuscular and intranasal administration was observed at experimental influenza infection of white mice.

Animals↗
PubMed1991

Two isoforms of Serratia marcescens nuclease. Crystallization and preliminary X-ray investigation of the enzyme.

Two isoforms of an extracellular endonuclease, nucleases Sm1 and Sm2, were purified from culture fluid of Serratia marcescens strain BIO MI by ligand-exchange chromatography on phosphocellulose and DEAE-Toyopearl 650S. The pI-values for nucleases Sm1 and Sm2 were found to be 7.1 and 6.7, respectively. The amino acid analysis and N-terminal amino acid sequencing of the proteins showed a significant degree of homology between the enzymes. The nuclease Sm1 has been crystallized from ammonium sulfate solution by the vapour diffusion technique. The crystals belong to the space group P2(1)2(1)2(1) with unit cell constants a = 69.0, b = 106.7, c = 74.8 A, contain two molecules in an asymmetric unit, packing density Vm = 2.3 A/Da, and diffract to at least 1.5 A resolution. The Pt- and UO2-derivatives of the protein were obtained. Preliminary X-ray investigation of nuclease Sm2 crystals was carried out.

Amino Acid Sequence↗
PubMed1990

[Isolation of isoforms and crystallization of endonucleases of Serratia marcescens].

Two isoforms of an extracellular endonuclease, nuclease Sm1 and nuclease Sm2, were isolated from the culture filtrate of Serratia marcescens strain B10 M1 by the ligand-exchange chromatography on iminodiacetate-agarose in Cu2(+)-form, and chromatography on phosphocellulose and DEAE-Toyopearl 650S. The pI for nucleases Sm1 and Sm2 were found to be 7.1 and 6.7, respectively. The amino acid analysis and N-terminal amino acid sequencing of the proteins showed a significant degree of homology between the enzymes. The secondary structure of nuclease Sm2 was calculated. Crystals of nuclease Sm2 were obtained with the space group P2(1)2(1)2(1), a 69.0; b 106.7; c 74.8 A.

Amino Acid Sequence↗
PubMed1990

[Ligand-exchange chromatography of proteins and enzymes].

Current state of the ligand-exchange chromatography (metal chelate affinity chromatography) of proteins and enzymes is reviewed. This technique is based on the ability of proteins to bind metal ions immobilized on chelate gels. The influence of pH, composition of buffer, type of stationary ligand and nature of metal ions on the chromatographic behaviour of proteins is discussed.

Chromatography, Affinity↗
PubMed1986

Ligand-exchange chromatography of nucleases.

The synthesis of chelating sorbents for ligand-exchange chromatography of enzymes is described. An inorganic support "Silochrom" and organic "Spheron", TSK-Gel HW 55 and cellulose were used as initial supports. The chelating sorbents contained iminodiacetic acid and iminodimethylphosphonic acid as stationary ligands. In order to obtain monofunctional sorbents, iminodiacetic acid was added in the form of its dimethyl ester. The concentration of stationary ligands on the sorbents varied from 10 to 100 mumol per ml sorbent. A chelating sorbent (in nickel form) was shown to be effective in the purification of exonuclease A5 from actinomyces. Electrophoretically homogeneous exonuclease A5 was obtained with a 25% yield. A chelating sorbent with iminodiacetic groups (in copper form) was applied to the isolation of endonuclease from Serratia marcescens directly from the culture medium. The capacity of the chelating sorbents for the endonuclease was studied as a function of the stationary ligand concentration. After one stage of purification, more than 70% pure enzyme was obtained with a yield exceeding 80%.

Actinomyces↗
PubMed1984

[Affinity chromatography of nucleases].

The review concerns isolation and purification of nucleases by affinity chromatography. Different stationary ligands and the methods for their immobilization on supports are described, along with diverse eluents and various procedures for a nuclease detachment from the affinity sorbents. The data on the affinity chromatography application for measuring the dissociation constants of the enzyme complexes with either immobilized or soluble ligands are compiled.

Animals↗
PubMed1980

[DNA immobilization on modified inorganic sorbents].

Fragments of denaturated DNA having the length of about 500 nucleotides were immobilized, using silica carriers modified by organic polymers. It was shown that the organic coating allows to obtain sorbents, which practically exclude non-specific sorption with respect to DNA. The immobilization was carried out on hydroxyl-containing sorbents and on their phrosphorylated derivatives by means of water-soluble carbodiimide. The resulting preparations contained up to 60 units at A260 of DNA per 1 g of carrier. The effects of endonuclease A236, exonuclease A5 and pancreatic DNAse on the immobilized RNA were studied.

Adsorption↗
PubMedDate not supplied

[The study of the metal-binding region in human growth hormone using immobilized metal ion affinity gel-electrophoresis].

The zinc(II)-binding affinities of recombinant human growth hormone and two its mutants, 14-33 and 14-95, were studied using Immobilized Metal Ion Affinity Gel-electrophoresis (IMAG). The mutant hormones, composed of polypeptide chain segments of the human and porcine growth hormones, lacked His18, which may be crucial for binding of the intact hormone to the transition metal ions. The mutations did not affect the affinity of human growth hormone to immobilized zinc ions; the structural analysis implied that the human growth hormone contains two IDA-Zn(II) potential sorption sites formed by amino acid residues His21, Asp171, and Glu174 and/or His18 and Glu174.

Animals↗