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Biomedical subjects

S V Kaliuzhnyĭ

Publications and source records attributed to S V Kaliuzhnyĭ.

5 recordsLinked to original sources
PubMed1993

[Purification and some properties of Clostridium thermocellum endoglucanase, formed by a recombinant Escherichia coli strain].

The endoglucanase (EG5) has been isolated from the recombinant strain of E. coli TG1 carrying a plasmid with C. thermocellum F7 chromosomal DNA insertion. Using high performance ion-exchange chromatography and chromatofocusing, the enzyme was 98-fold purified with a 27% yield. The enzyme has a molecular mass of 35 kDa (SDS-PAGE data) and is represented by three isoforms with pI 4.4-4.8 (isoelectrofocusing data). The activity of EG5 was determined by chromatography on carboxymethylcellulose, amorphous cellulose, xylan, lichenan and avicel. The optimal conditions for these substrates hydrolysis are: pH 6.0-6.5, 80 degrees C (60 degrees C for avicel).

Cellulase↗
PubMed1991

[Biochemical kinetics of plasmid replication processes].

Two groups of plasmid replication reactions occurring during the growth of cell populations were kinetically characterized: 1) short-term intermediate processes coupled with changes in plasmid concentrations in host cells and occurring in the first few generations; 2) long-term processes resulting in the loss of plasmids and occurring during prolonged cultivation of cells. It was shown that first group processes are determined by the ratios of plasmid replication rates relative to cell growth. Using growing populations of E. coli as examples, it was shown that the shape of kinetic curves reflecting the plasmid copy number depends on the nature of their replicon. In this case plasmids with ColE1 replicon exhibit kinetic behaviour of the first type (temporal loss of plasmid copy number in the cells), whereas plasmids with p15 replicon display the second type behaviour consisting in the decrease of the plasmid copy number followed by its short-term drastic increase. For both types of kinetic behaviour a kinetic description adequately reflecting these processes is given. It is supposed that the loss of plasmids during long-term cultivation of cell populations may be associated with both segregation (lower growth rates of plasmid-containing cells in comparison with cells containing no plasmids) and mutation mechanisms. Kinetic descriptions of both mechanisms are proposed and principles of their discrimination are formulated. Practical recommendations for the prevention of the plasmid loss by the cells that are based on theoretical data are given.

Kinetics↗
PubMedDate not supplied

[Nucleotide sequence of the pNB2 plasmid from thermophilic bacteria Clostridium thermosaccharolyticum].

The complete nucleotide sequence of pNB2, a 1.9-kilobases cryptic plasmid from thermophilic Clostridium thermosaccharolyticum has been determined. The plasmid consists of 1882 base pairs and has a G+C composition of 27.2%. The sequence contains three open reading frames capable of coding for polypeptides two of which were identified in maxicell Escherichia coli extracts. Our future studies are directed toward a construction of pNB2-derivatives as vectors for Clostridia.

Amino Acid Sequence↗
PubMedDate not supplied

[Anaerobic microbial associations degrading aromatic amino acids].

Anaerobic microbial associations have been isolated that degrade aromatic amino acids to methane and carbon dioxide at high rates. Significant differences between the morphological, cytological, and physiological traits of cultures isolated from samples of adapted and unadapted sludge are shown. The effects of cultivation temperature, illumination, and presence of mineral nitrogen and bicarbonate in the medium upon adaptation of enrichment cultures to substrates and subsequent behavior of the anaerobic associations have been studied. Intermediate and final products of degradation of aminoaromatic compounds and the sequence of their formation in the cultures have been determined. We have also studied the effects of exogenous electron acceptors and additional carbon sources on the degradation of aminoaromatic compounds.

Amino Acids, Aromatic↗