Search PubMed⌕ Search

Biomedical subjects

V V Demin

Publications and source records attributed to V V Demin.

28 records · Page 2Linked to original sources
PubMed1986

[Synthesis and immunochemical study of the antigenic determinant of the H-2Db molecule of the murine major histocompatibility complex].

Primary structure of murine class I histocompatibility antigens has been analysed to select possible antigenic determinant. Hexapeptide Leu-Gln-Gln-Leu-Ser-Gly, homologous to the region 95-100 of the H-2Db antigen heavy chain, was synthesised by stepwise elongation of peptide chain beginning from the COOH-terminal Gly. Rabbit anti-hexapeptide antibodies were obtained and shown to interact specifically with purified H-2Db antigen as well as with the native antigen on cell surface. These antibodies bind to lymphocytes of H-2b haplotype (C57BL/6 mice) but not H-2d (BALB/c) or H-2k (CBA). These data suggest that the region 95-100 is responsible for serologic differences between the alleles of H-2 antigens, i.e. it may be a xenotypic as well as an allotypic antigenic determinant. The latter was confirmed by study of interaction of the hexapeptide with allogeneic monoclonal antibodies specific to H-2Db antigen.

Animals↗
PubMed1985

Three-dimensional structure of (Na+ + K+)-ATPase revealed by electron microscopy of two-dimensional crystals.

Prolonged incubation of membrane fragments containing homogeneous (Na+ + K+)-ATPase with Mg2+, K+ and VO-3 at 4 degrees C resulted in formation of two-dimensional crystals of this enzyme with unit cell parameters: a = 66 A, b = 118 A, gamma = 108 degrees. The crystals correspond to the two-sided plane group p21. By combining tilted electron microscopic views of the crystals, a three-dimensional structure of (Na+ + K+)- ATPase was calculated at approximately 20 A resolution. The unit cell is formed by two (alpha beta)-promoters which are in contact in their central parts. The structure was compared with chemical modification and immunochemical data; the arrangement of intra- and extramembrane domains was proposed.

Animals↗
PubMed1976

[Energization of membrane vesicles from the cells of glycolyzing bacterium Streptococcus faecalis].

Membrane fractions were isolated from Streptococcus faecalis cells of a glycolyzing microorganism, devoid of the respiratory chain, using the methods of osmotic shock of the protoplasts, ultrasonic treatment of the cells and ultrasonic treatment of the protoplasts. All fractions possessed the ATPase activity, the highest activity being observed in the fraction isolated by ultrasonication of the protoplasts. All preparations were estimated with respect to the presence of vesicles, formed by the "inside-out" and "inside-in" membranes, using ATPase as a marker of the membrane orientation. In the membrane fractions obtained by ultrasonication of the protoplasts, the "inside-out" vesicles were prevalent. ATP-dependent energization of the membranes, sensitive to the action of dicyclohexylcarbodiimide and tetrachlorotrifluoromethyl benzimidazole, was demonstrated by measuring the transport of the lipophylic anion of phenyldicarbaundecaborane and aniline naphthalene sulfonate fluorescence.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Effect of supporting substrates on the structure of DNA and DNA-trivaline complexes studied by atomic force microscopy].

Linear DNA, circular DNA, and circular DNA complexes with trivaline (TV), a synthetic oligopeptide, were imaged by atomic force microscopy (AFM) using mica as a conventional supporting substrate and modified highly ordered pyrolytic graphite (HOPG) as an alternative substrate. A method of modifying the HOPG surface was developed that enabled the adsorption of DNA and DNA-TV complexes onto this surface. On mica, both purified DNA and DNA-TV complexes were shown to undergo significant structural distortions: DNA molecules decrease in height and DNA-TP displays substantial changes in the shape of its circular compact structures. Use of the HOPG support helps preserve the structural integrity of the complexes and increase the measured height of DNA molecules up to 2 nm. AFM with the HOPG support was shown to efficiently reveal the particular points of the complexes where, according to known models of their organization, a great number of bent DNA fibers meet. These results provide additional information on DNA organization in its complexes with TV and are also of methodological interest, since the use of the modified HOPG may widen the possibilities of AFM in studying DNA and its complexes with various ligands.

Adsorption↗
PubMedDate not supplied

[Differences in the cellular surface of hybrid Escherichia coli K12 bacteria inheriting the rfb a3,4 gene of Shigella flexneri detected using atomic-force microscopy].

The cell surface of E. coli initial parent strain K12 J62 his-, chemotype Ra, and E. coli transductant strain K12 J62 his+, acquiring the capacity for synthesizing primary S-specific side chains of the lipopolysaccharide of S. flexneri O-antigen (group-specific factor 3,4), was studied by the method of atomic force microscopy. The comparative analysis of the images of the genetically linked pair of E.coli strains K12 J62 revealed the presence of essential differences in the topography of the surface structure of the compared bacterial cells, differing in their capacity for synthesizing S. flexneri factor 3,4 represented by repeating chains of L-rhamnose and N-acetyl-D-glucosamine.

Antigens, Bacterial↗