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V L Tsuprun

Publications and source records attributed to V L Tsuprun.

At least 37 records · Page 2Linked to original sources
PubMed1989

Coenzyme non-specific glutamate dehydrogenase from Chlorella pyrenoidosa 82T: electron microscopic studies.

The constitutive coenzyme non-specific glutamate dehydrogenase (GDH) from Chlorella pyrenoidosa 82T was purified to homogeneity by column immunoaffinity chromatography and examined by an electron microscope. The enzyme molecule was found to be a hexameric oligomer composed of monomers arranged in three 2-point group symmetry in two layers slightly twisted round the 3-fold axis. The molecule is 8 +/- 1 nm in diameter and 10 +/- 1 nm in height. The enzyme molecules appear both to dissociate into trimers and to associate along the 3-fold axis forming linear aggregates under certain conditions. A tentative model of the Chlorella GDH molecule is proposed, which is very similar to those described for bovine liver GDH and GDH from Clostridium symbiosum.

Chlorella↗
PubMed1989

Structure of the ATP-synthase studied by electron microscopy and image processing.

The structure of ATP synthase from beef heart mitochondria has been studied by electron microscopy and image processing using negatively stained specimens of detergent-solubilized and membrane-bound molecules. The F1-ATPase and the membrane-embedded F0 sector of ATP synthase are found to be connected by a narrow stalk, 4-4.5 nm long and 3-3.5 nm wide, projecting about 4.2 nm from the membrane surface. The F0 sector has a globular shape, 6-8 nm in diameter and, in part, extends from the membrane lipid bilayer.

Animals↗
PubMed1988

Association of rabbit muscle glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase. The biochemical and electron-microscopic evidence.

Rabbit muscle glyceraldehyde-3-phosphate dehydrogenase covalently bound to Sepharose was shown to form a complex with soluble 3-phosphoglycerate kinase. The strength of the association appeared to depend upon the functional state of both enzymes. The holoform of the dehydrogenase exhibited a lower affinity for the kinase than the enzyme-3-phosphoglycerol.NADH complex. The substrate-free 3-phosphoglycerate kinase associated much stronger with the acylated dehydrogenase than the kinase in complex with 1,3-diphosphoglycerate. Electron-microscopic evidence for the association of the soluble acyl-glyceraldehyde-3-phosphate dehydrogenase.NADH complex and 3-phosphoglycerate kinase was also obtained.

Animals↗
PubMed1987

Electron-microscopic studies on location of SH-groups in mitochondrial F1-ATPase using a ferritin label.

A new approach has been suggested for electron-microscopic study of the structure of mitochondrial F1-ATPase based on ferritin labeling. By means of sequential treatment with 2-iminothiolane and Nbs2 we obtained a modified ferritin (NbsSPrCNH-Ft) able to react with SH-groups of proteins and to form conjugates in which the protein and ferritin are bound by disulfide bonds. An electron-microscopic investigation of the negatively stained preparations of mitochondrial F1-ATPase, preincubated with modified ferritin, revealed such enzyme-ferritin conjugates. In case of modified ferritin, containing 360 mol SH-groups per mol protein, and F1-ATPase, pretreated with N-ethylmaleimide and then with dithiothreitol, conjugates were obtained in which ferritin molecules are bound to several (as many as four) of the six protein masses, comprising a bilayer molecule of the enzyme. Taking into consideration the biochemical data on the location of accessible SH-groups (only in alpha, gamma or epsilon subunits), it is inferred from the results obtained that one of the protein masses is a complex between beta subunit and at least one of the minor subunits located partially on the molecule's external side. This indicates the nonequivalence of different copies of the major subunits. Averaged images of the particles of the F1-F0 complex from bovine heart mitochondria and bacteria Micrococcus lysodeicticus were obtained. It was found that F0 component is bound to two adjacent protein masses of the F1-ATPase molecule. It is suggested that this binding may be due the nonequivalency of single-type major subunits.

Animals↗
PubMed1986

Quaternary structure of the liver microsomal cytochrome P-450.

Cytochrome P-450LM2 was isolated from rabbit liver microsomes in a form which was shown to be homogeneous in AcA-22 Ultrogel and ultracentrifugation studies. The molecular mass determined by sedimentation equilibrium roughly corresponded to hexamer composed of 56 kDa monomers. Hexamer structure of the cytochrome was directly demonstrated by electron microscopic study. In the cytochrome P-450LM2 hexamer, monomers seem to be arranged in two layers (three monomers in the layer) in such a way that each monomer occupies a position at the vertices of a triangular antiprism with a 32 point group symmetry.

Animals↗
PubMed1985

Electron microscopy of the Mo-Fe-protein from Azotobacter vinelandii nitrogenase.

The quaternary structure of the Mo-Fe-protein from Azotobacter vinelandii has been studied by electron microscopy. A model of the molecule of the Mo-Fe-protein has been proposed: two alpha subunits are displaced relative to two beta subunits along a twofold axis, so the molecule can be characterized by the point-group pseudosymmetry 222. Computer averaging of the images showed that one of the projections of the molecule could be characterized by twofold rotational symmetry. Micrographs of nitrogenase recombined complex (Mo-Fe-protein + Fe-protein) have been obtained. They showed particles close in size and form to the Mo-Fe-protein molecule. Therefore, it has been proposed that the Fe-protein could be situated in the central cavity of Mo-Fe-protein.

Azotobacter↗
PubMed1984

Electron microscopy of beef heart mitochondrial F1-ATPase.

The quaternary structure of isolated and membrane-bound F1-ATPase (submitochondrial particles) has been studied by electron microscopy. A model of the molecule has been proposed: six protein masses are arranged in two layers approximately at the vertices of a triangular antiprism. Computer averaging of the images showed that the frontal view of the molecule can be approximately characterized by mirror plane symmetry.

Animals↗
PubMed1983

[High molecular weight protein consisting of 14 monomers from pea leaves].

A new high molecular weight protein has been detected in pea leaves. Using electron microscopy it has been demonstrated that this protein consists of 14 identical monomers with a point 72 symmetry arranged in two layers, 7 monomers in each. The molecular weight of the protein as determined by gel filtration and sedimentation equilibrium method is equal to 900000 +/- 150000 and 950000 +/- 50000, respectively. The sedimentation coefficient for the protein is 24.3 +/- 1.0S. During SDS polyacrylamide gel electrophoresis the protein dissociates into identical polypeptide chains with molecular weight of 67000 +/- 3000. The circular dichroism spectra of the protein reveal that the percentage of alpha-helix portions, beta-structures, beta-turns and irregular portions is 0.45 +/- 0.06, 0.31 +/- 0.03, 0.09 +/- 0.03 and 0.15 +/- 0.07, respectively. The protein possesses a weak ATPase activity. The protein content in the leaves changes in the course of development.

Circular Dichroism↗
PubMed1980

Electron microscopy of glutamine synthetase from pea leaf chloroplasts.

The structure of pea leaf chloroplast glutamine synthetase was studied by electron microscopy. The enzyme is shown to consist of eight elongated subunits which are arranged with point 42 symmetry at the vertices of two squares. These squares are twisted about the 4-fold axis at 40 degrees relative to each other.

Chloroplasts↗
PubMed1977

On the quaternary structure of leucine aminopeptidase.

Small crystals of leucine aminopeptidase were prepared in 2 percent ammonium molybdate. Single molecules were contrasted with 2 percent potassium silico tungstate which gave better contrast and preservation of enzyme activity than ammonium molybdate. The six subunits of the enzyme consist of a spheroidal "head" and some "tail-like" material, which connects the "heads" in pairs. The subunits are arranged at the vertices of either a right triangular prism or of an oblique prism twisted by 42 degree (symmetry 32).

Animals↗