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Biomedical subjects

O V Krasil'nikov

Publications and source records attributed to O V Krasil'nikov.

At least 19 recordsLinked to original sources
PubMed1990

[Channel-forming proteins. III. Colicins].

A brief review is devoted to the results of the study of molecular mechanism interaction between membrane-active colicins and membranes in model systems. The data on physical-chemical properties of colicins most studied, the relationship between the structure and the properties of ion channels formed by them in membranes are given. The characteristics of such channels, the dependence of their functioning on the composition of aqueous medium and on transmembrane potential are discussed in detail. The hypotheses on the structure of colicin channels and experimental data concerning the size of their water pore ane considered.

Bacterial Proteins↗
PubMed1989

[Proteins--channel formers. II. Porins and proteins of the external mitochondrial membranes].

The physical and chemical properties in protein external membranes of gram-negative bacteria and mitochondria are considered. A possible evolutional affinity between these proteins is discussed. The data on peculiarities of their polypeptide chain structure depending on environmental parameters and chemical modification of ionogeneous groups of protein-channel formers as well on a possible structure of water pore in ion channels are presented.

Bacterial Outer Membrane Proteins↗
PubMed1985

[Changes in the membrane surface charge and the potentiation of phospholipase A2 as affected by the cytotoxin from the venom of the Central Asian cobra].

The interaction of iodine labelled cytotoxin of the middle-asian cobra venom with erythrocyte membranes has been studied. The pretreatment of erythrocytes by cytotoxin results in the sensitivity to the lytic action of pure phospholipase A2 of the same venom. Using I-labelled serum albumin it has been proved that cytotoxin promotes the binding of acid proteins on the membrane such as phospholipase A2 interacted with it synergetically. In the course of study of cytotoxin effect on the time of adhesion hemispheres of artificial bilayer phospholipide membranes it has been established that due to the basic properties cytotoxin neutralizes the negative charge of the membrane surface. This effect of cytotoxin plays an important role in the potentiation of membrane action of phospholipase A2.

Cobra Neurotoxin Proteins↗
PubMed1980

[Effect of tenoyltrifluoroacetone on the functioning of mitochondria and other membrane structures].

The effects of tenoyltrifluoroacetone (TTFA) on respiration and oxidative phosphorylation of rat liver mitochondria and on the permeability of inner mitochondrial membranes for mono- and divalent cations were studied. It was shown that TTFA, beside being an inhibitor of succinate oxidation and oxidative phosphorylation uncoupler increases the permeability of mitochondria, sarcoplasmic reticulum fragments, liposomes and bilayer phospholipid membranes for Ca2+. The TTFA (150 mkM)-induced permeability of mitochondria for various cations decreases in the following order: Ca2+: H+: Mg2+: Sr2: Ba2+: K+: Na+ = 1:0,07: 0,06: 0,02: 0,015: 0,01. TTFA predominantly stimulates the Ca2+/H+ or Ca2+/Na+ exchange; the membrane-active effects of TTFA are enhanced in the presence of the hydrophobic anion tetraphenylborate and the neutral electron-donating compound tributylphosphate.

Animals↗
PubMedDate not supplied

[Ionic selectivity of melittin-modified flat lipid bilayers].

It has been established in experiments with the bilayer lipid membranes (BLM) that at pH greater than 6.6 the melittin pores are cation-selective and at lower pH they are more selective by anions. The property of melittin pores is shown to be provided by the amino group of the N-terminal glycine residue. The selectivity of melittin-containing membranes may be controlled by the transmembrane potential, the cross-section of water pores being changed. The data obtained are explained within the alimethicine-like model.

Bee Venoms↗
PubMedDate not supplied

[Selectivity of latrotoxin channel in lipid bilayers].

It is established that high initial K-TEA and Ca2(+)-K+ selectivity of channel form by latrotoxin in lipid bilayers (LT-channel) may be reduced by lowering the pH value and by increasing electrolytes concentration of solution. It is suggested that LT-channel is water-filled pore cation selectivity which is defined by the electrostatic potential on the mouth of the channel, which is induced by the ionogenic group of toxin.

Biological Transport↗
PubMedDate not supplied

[The effect of anions on the hemolytic activity of melittin].

Anions causing the melittin aggregation in the solution are shown to slow down the lytic process not preventing it completely. The equalization of the oncotic gradient through the erythrocytic membrane by the addition of polyethylene glycols of different molecular weight into the extracellular medium made it possible to establish the colloid-osmotic mechanism of hemolysis and to estimate the diameter of melittin pores. The diameter depends on the polypeptide concentration and makes up 20-30 A with its content of (6 divided by 12).10(-6) M.

Animals↗
PubMedDate not supplied

[Membrane activity of a cell-free filtrate of Shigella flexneri 2a].

In the course of metabolism in Shigella Flexneri 2A strain there was noted secretion of a membrane-tropic factor into media. This factor increased the conductivity of bilayer lipid membranes causing formation of ionic channels in them. Minimal conductivity of the channels was about 25 pS in 0.5 M NaCl; at PH 7-8 the channels exhibited cation-anion selectivity. The calculated number of cation transfer (T+) was elevated with an increase in the channel amplitude, approaching 0.86. Since the conductivity of the channels depended on the definite potential, the component studied appears to have an intracellular localization under normal conditions; possible mechanism of its liberation into surrounding medium is discussed.

Animals↗
PubMedDate not supplied

[Cation-anion selectivity of staphylococcal channels in the lipid bilayer].

It has been found that cation-anion selectivity of staphylotoxin channels in BLM of different lipid composition is determined by summary charge of ionogenic groups of protein-channel-former exhibited to the water phase. Interrelationship of staphylotoxin channel functioning is substantiated.

Animals↗
PubMedDate not supplied

[Effect of pH on the potential-dependent functioning of staphylococcal toxin channels in phosphatidylcholine bilayer].

Potential-dependence of staphylococcal toxin channels at neutral pH is poorly expressed and increases with the medium acidation. It is shown that the value of the translocating charge is practically unchanged, whereas the energy parameters of this process vary essentially. The data obtained indicate the asymmetrical disposition of ionogenic channel groups determining its behaviour in the electric field.

Bacterial Toxins↗
PubMedDate not supplied

[Conductivity and diameter of latrotoxin channels in lipid bilayers].

It is shown that approximately 9 A Ca-selective ion channels were induced in bilayer lipid membrane (BLM) from phosphatidylserine by nonpurified spider venom (Latrodectus tredicimguttatus) and by alpha-latrotoxin obtained from it. It is established that channels greatly different in conductivity have the same diameter and nearly the same charge constitution, that evidences for their claster organization. The purification process as well as freezing-thawing and long time keeping influence the channel conductivity without changing its diameter and selectivity.

Arthropod Venoms↗