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V I Karamushka

Publications and source records attributed to V I Karamushka.

16 recordsLinked to original sources
PubMed1999

Interaction of Saccharomyces cerevisiae with gold: toxicity and accumulation.

This paper examines the effects of ionic gold on Saccharomyces cerevisiae, as determined by long-term (growth in gold-containing media) and short-term interactions (H+ efflux activity). An increasing gold concentration inhibited growth and at < 0.2 mM Au, growth was not observed. Transmission electron microscopy revealed no differences in ultrastructure but fine electron dense particles were observed in unstained preparations from gold-containing medium. After glucose addition (to 10 mM) to starved suspensions of S. cerevisiae, glucose-dependent reduction of external pH occurred as the cells extruded protons. In the presence of increasing gold concentrations, the lag time before proton extrusion did not change but the rate and duration decreased significantly with a marked influence on proton efflux rate being observed at < or = 10 microM. Extension of preincubation time of yeast cells in gold-containing medium resulted in a decreasing proton efflux rate and colloidal phase formation in the cell suspensions, the time between gold addition and the beginning of colloidal phase formation depending on the gold concentration used. Both Ca and Mg enhanced the inhibitory effect of gold on the yeast cells with Ca showing a stronger inhibitory effect than Mg.

Biological Transport↗
PubMed1994

Influence of copper on proton efflux from Saccharomyces cerevisiae and the protective effect of calcium and magnesium.

The inhibitory effect of Cu on glucose-dependent H+ efflux from Saccharomyces cerevisiae was manifest at low (micromolar) concentrations, with the time period between the addition of glucose and commencement of H+ efflux, H+ efflux rate and duration all being affected with increasing Cu concentration (5-100 microM). Ca, at a concentration of 0.5 mM, completely removed the inhibitory effect of Cu at concentrations up to 50 microM and considerably reduced it at higher concentrations (up to 150 microM). Mg exhibited a similar but weaker protective effect against the influence of Cu. The protective effect of Ca against 50 microM Cu was evident at low Ca concentrations (2.5-5 microM), whereas Mg was effective at > or = 50 microM. In order to prevent the inhibitory effect of Cu, it was necessary to add Ca or Mg to the cell suspension before Cu addition. It is concluded that the protective effect of Ca and Mg is mediated by competitive and stabilizing interactions at the cell surface as well as physiological functions of Ca and Mg.

Calcium↗
PubMed1992

Interaction of energized bacteria cells with particles of colloidal gold: peculiarities and kinetic model of the process.

It is found that the cells of Bacillus cereus B-4368 at energized state can concentrate the colloidal gold particles on their surface. It is shown that the process depends on metabolic reactions proceeding on the plasma membrane. The inhibitory analysis permits to suppose that the metal concentration is due to the functioning of ATP-dependent generator of the transmembrane potential, apparently, of proton ATPase. Kinetic characteristics of the process show the presence of an intermediate state in the formation of biomineral aggregates. A kinetic model of the studied process is suggested which describes the experimental data well.

Adenosine Triphosphatases↗
PubMed1985

[Interaction of smooth muscle plasma membranes with flat lipid membranes].

The method of implantation of smooth muscle cells from plasma membranes (PM) of the rabbit intestine into flat lipid membranes (FLM) is described. The method is based on the pretreatment of PM vesicles with asolectin liposomes in the ratio that provides the activation of membrane ATPases. Thus modified FLM possesses channel conductivity.

Adenosine Triphosphatases↗
PubMed1984

[Mg2,Ca2+-ATPase activity of sarcolemmas of intestinal smooth muscle cells in the rabbit].

Preparations of rabbit small intestine smooth muscle cell sarcolemma are capable of hydrolyzing ATP in the presence of millimolar concentrations of Mg2+ and Ca2+ and possess the activity of Mg2+,Ca2+-ATPase having a high affinity for Ca2+ (Km = 5.8 X 10(-6) M). The optimal conditions for the Mg2+,Ca2+-ATPase reaction were established. It was demonstrated that sarcolemmal preparations hydrolyze ATP, GTP, ITP and UTP almost at the same rates. The enzyme contains SH-groups that are unequally exposed to the water phase and are inhibited by 50% by p-chloromercurybenzoate and by 90% by dithionitrobenzoate. The Mg2+,Ca2+-ATPase activity is highly sensitive to oxytocin: at the concentration of 10(-7) MU/ml, the hormone completely inhibits the enzyme without affecting its Mg2+-, Ca2+- and Na+,K+-ATPase activities.

Adenosine Triphosphate↗
PubMed1984

[Extraction of plasma membranes from smooth muscle cells of the rabbit small intestine].

A method is offered for isolation of subcellular fractions from small intestinal smooth muscle cells enriched by plasma membranes (PM). The method is based on differential centrifugation over sucrose density gradient. According to the localization of marker enzymes, the membrane fraction obtained with the use of 30% sucrose is considered to be optimal. The PM fraction is superior to the homogenate 10-fold on the average in the magnitude of Na, K-ATPase, 17-fold in Mg2+-ATPase, and 15-fold in that of 5'-nucleotidase activity. ATPase of PM is activated by Ca2+ in micro- and millimolar concentrations. It is suggested that Mg2+-dependent Ca-activated ATPase of PM is related to the Ca2+ content control in the cell.

Animals↗
PubMed1983

[Surface activity of plasma membranes].

Plasma membranes of rabbit intestinal smooth muscle cells manifest low surface activity on the boundary of the electrolyte-air phases. This activity undergoes essential changes if the electrolyte surface is covered with the lecithin monolayer. According to the experimental data, the interaction of plasma membranes with the lecithin monolayers is hydrophobic in nature and essentially depends on the density of molecular packing of phospholipids in the monolayer and on the status of the membrane preparation. A possible mechanism of the formation of the monolayer patterns from cell membranes is discussed.

Animals↗
PubMedDate not supplied

[The effect of respiratory toxins on the bacterial concentration of trivalent gold].

It has been found that concentration of trivalent gold by Bacillus cereus V-4368 cells is sensitive to respiratory inhibitors such as rotenone and antimycin A. Inhibitory action of rotenone is neutralized by succinate, that of antimycin--by ATP. ATP influence disappears in presence of DCCD. It is supposed that Au(III) concentration is due to the ATPase action and the respiration systems supply this process with ATP.

Adenosine Triphosphate↗
PubMedDate not supplied

[The role of membrane processes in Au(III) and Au(0) accumulation by bacteria].

The role of structural and functional factors in the processes of the bacterial cell interaction with colloid Au (0) and ionic Au (III) states has been investigated. It is shown that the bacterial walls of Bacillus sp. 4368 aggregating with colloid gold contain glycoprotein with isoelectric point 11. Glycoprotein from cell walls indifferent to colloid gold strain (Bacillus subtilis 168) has pHiso = 5. At the same time the cells of both strains accumulate Au (III) introduced into a medium in the form of tetrachloroaurate. The process is energy-dependent because it is suppressed by azide, uncouplers of oxidative phosphorylation and dicyclohexyl carbodiimide (DCCD). The role of ATPase of Au (III) accumulation has been studied on Bacillus sp. 4368 plasma membrane vesicles. The ATPase activity is inhibited by 70, 50 and 35-50% by vanadate, DCCD and Au (III), respectively, but it does not change in the presence of dinitrophenol and NaN3. ATP but not ADP and AMP stimulated the Au (III) accumulation by membrane vesicles and prevents the inhibitory action of azide but neither of DNP or DCCD. In the energized state membrane vesicles link gold sol particles. It has been assumed that the Au (III) accumulation is associated with the functioning of transmembrane potential generators, the metal being localized on the membrane surface.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Effect of n-chloromercuribenzoate and albumin on Mg2+, Ca2+-ATPase activity of plasma membranes of smooth muscle cells].

It is shown that Mg2+, Ca2+-ATPase activity of plasma membrane fragments from the rat small intestine myocytes is inhibited by p-chloromercuribenzoate and dithionitrobenzoate (50 and 90%, respectively). The effect of p-chloromercuribenzoate inhibition is removed by serum albumin promoting a rise in the ATPase activity of the plasma membranes and shifting the temperature maximum point up to 32 degrees C (in the norm the maximum is observed at 36 degrees C). According to the data presented, albumin changes the composition and phase state of the lipid surrounding of the membrane enzymes.

Albumins↗
PubMedDate not supplied

[Interaction of the glycoprotein from the Bacillus pumilis cell wall with liposomes].

The methods of centrifugation and gel-filtration on Sephadexes G-50 and G-150 were used to study the interaction of Bacillus pumilis cell wall glycoprotein component having the molecular weight of 50 kDa (GP-50) with lyposomes from bacterial lipids. GP-50 is shown to sorb on such liposomes and disturb their barrier properties inducing yield of low-molecular label. GP-50 exerts no effect on properties of liposomes from egg lecithin. Electrostatic forces are supposed to play a decisive role in initial acts of GP-50 interactions with lipid phase of microbial envelopes.

Bacillus↗
PubMedDate not supplied

[Reconstruction of the properties of smooth-muscle cell sarcolemma on planar lipid membranes].

A method is described for reconstruction of certain sarcolemma characteristics of smooth muscle cells in the small intestine of a rabbit on the planar lipid membranes (PLM). The method is based on the use of fusogenic properties of certain lipid preparations. The ultrasound dispergates of azolectin and egg lecithin in combined incubation with sarcolemma vesicles of smooth-muscle cells promote a 1.4-1.8-fold increase of the total ATPase activity of the sarcolemma. Cholesterol, dipalmithoil lecithin, total brain phospholipids, inhibit the ATPase activity. Sarcolemma vesicles preincubated with azolectin lyposomes in the ratio which induces maximum ATPase activation (sarcolemma protein: azolectin-1:6) interact intensively with PLM from azolectin. PLM modified in such a way is channel-conductive, sensitive to tetraethylammonium and sign of the applied voltage.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Bacterial cell membrane ATPase in assessing heavy metal toxicity].

Sensitivity of membrane ATPase to heavy metals was studied in bacterial stains Bacillus cereus ATCC 14579, Bacillus cereus B4368, and Alcaligenes eutrophus CH34 was studied. The inhibition effects of metals on membrane ATPase ranged in the same order (Au > Cu > Zn > Co > Mn) as their effects on the growth of cultures. It is suggested that membrane ATPase is one of the targets for the action of heavy metal ions within the microbial cell and, therefore, its activity may serve as an indicator of their toxicity.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Transmembrane potential and ATP-ase activity of the plasma membrane of bacteria exposed to heavy metals].

Effect of heavy metals (gold, zinc and cadmium) on the ATPase activity and transmembrane potential (delta psi) as integral index of bacterial cells membrane processes intensity has been studied. It was shown that studied membrane systems of bacteria are very sensitive to the action of heavy metals and they can serve as indicators of resistance of bacterial cultures.

Adenosine Triphosphatases↗