[Theory of electric clamp of lipid bilayer membranes. Splitting of the energy barrier]. / K teorii élektricheskogo proboia bisloinykh lipidnykh membran. Rasshcheplenie énergeticheskogo bar'era.

Various approaches to the investigation of bimolecular membranes are as a rule based on the notions of membrane structural defects. Usually such defects are presented as through hydrophylic pores. Relationship between free energy of the system and the defect size which is differently calculated in different concrete models (1-4) plays a principal role in the kinetic stability theory (5, 6). In the work (7) devoted to the theory of BLM electric clamp the free energy was calculated assuming low conductance of the defect. Refusal of this assumption leads to a significant change of the system free energy in relation to the defect radius.

[Polaron mechanism of ion transport through membranes]. / Poliaronnyi mekhanizm transporta ionov cherez membrany.

A complex formed by an ion together with polar molecules of water concentrated around the ion inside the membrane is regarded as a polariton. The electric field strength inside the polariton has been calculated and used for estimating polariton free energy for different values of water concentration inside the membrane. The estimations indicate that the polariton mechanism of ionic transport is responsible for background conductivity of BLM. It is shown that free energy of the polariton is proportional of Z3/2, Z being the charge of the ion. In the case of "bold" ion this dependence is characterized by factor Z2. It is suggested that the through pores are formed in the process of an electrical breakdown of BLM also via polariton mechanism of ionic transport.

[Membrane interaction with regard to redistribution of charged components]. / Issledovanie vzaimodeistviia membran s uchetom pereraspredeleniia zarazhennykh komponentov.

A system of two plane charged bilayers in electrolyte solution was considered with regard to possible redistribution of the charged lipids under the effect of the electric field. Force and energy conditioned by electric and van der Waals interaction were analysed. Two possible mechanisms of charge redistribution were proposed and analysed: the lateral one and by the "flip-flop" type. The results for these redistribution types were compared with those for fixed charge density. Relationships between inner field on the membrane surface potential differences resulting forces and energies and the distance between the membranes and the effect of charge redistribution were analysed. The redistribution of the surface charge was shown to weaken the pushing part of the membranes and to decrease the intermembrane field, which promotes the adhesion without damaging the membrane structure.

[Energetic profile of dipole molecules in membranes]. / Energeticheskii profil' dipol'nykh molekul v membranakh.

Free energy of the dipole muscle inside the membrane in relation to its orientation and the distance to the membrane border was calculated. Efficient energy describing molecule concentration was found. Water concentration in BLM was evaluated by three methods: according to the membrane permeability to water, according to the data on interface equilibrium, and directly according to the value of calculated free energy. All methods give the value of the order of 10(-3) g/cm3. It has been shown that for the particles with a significant dipole momentum the work of particle transfer from the membrane surface into its depth comprises 3/8 of the complete work of interphase transition (for ions this ratio is 1/2).

[Interaction of membranes with constant surface charge]. / Vzaimodeistvie membran, nesushchikh postoiannyi poverkhnosthyi zariad.

A system of two plane charged bilayers in electrolyte solution is considered. Equilibrium criteria of such system under the effect of van der Waals attractive forces and electrostatic repulsive force were obtained, as well as aggregation criteria (it is assumed that surface charge density on the membrane is constant). Relationships between the membrane inner field, surface potential differences, as well as resulting forces and energies and the distances between the membranes were analysed.

[Potentiodynamic method of studying the reaction between liposomes and bilayer lipid membranes]. / Issledovanie vzaimodeistviia liposom s BLM potentsiodinamicheskim metodom.

Changes of surface potential difference of neutral BLM in the presence of negatively charged liposomes were controlled by means of potentiodynamic method. The liposomes were prepared by sonication of PS-suspension in buffer solution. BLM was formed conventionally from lecithin--decane mixture. Measurements were carried out in buffer solution 2 mM KCL, 5 mM Tris-Cl pH 7.6) at 30 degrees C. It is shown that the liposomes are irreversibly bound to BLM, but do not fuse with it under the conditions investigated.

[Liposome fusion with planar lipid membranes]. / Sliianie liposom s ploskoi lipidnoi membranoi.

Potentiodynamic method was used for investigating bilayer lipid membrane (BLM)- liposomes (LS) interaction. BLM was formed from egg lecithin and its mixture with phosphatidylserine (PS); LS-from PS. It is shown that in the presence of calcium in the aqueous phase (1-10 mM) and charged phospholipids in both LS and BLM, fusion of LS with BLM is observed. The fusion event was registered by measuring the increase of negative charge density on BLM surface opposite to that facing the LS.

[Dipole cooperative model of ion channels of excitable biomembranes. Conductance of ion channels]. / Dipol'naia kooperativnaia model' ionnykh kanalov vozbudimykh biomembran. Provodimost' ionnykh kanalov.

An analysis of ionic channel conductance is presented in terms of dipole cooperative model. The dependence of conductance on displaced charge is found to be an S-shaped function. Basing on this function and kinetics of gating currents, the kinetic curves for the conductance are calculated. These curves are compared with Hodgkin--Huxley results on sodium channel. A good agreement may be observed for the case of positive jumps of the potential. Less accurate coincidence takes place for negative jumps of the potential.

[Dipole cooperative model of ion channels in excitable biomembranes. I. Gating currents]. / Dipol'naia kooperativnaia model' ionnykh kanalov vozbusimykh biomembran. I. Vorotnye toki.

The experimental data on gating currents are analyzed in terms of dipole cooperative model of ionic channel. The dependence of displaced charge on potential is calculated. A comparison between the theory and experiment allows to establish the cooperative part of the charged gating subunits energy. It is shown that kinetics of gating particles displacement is nearly exponential. The theoretical dependence of characteristic times on the potential during testing pulse of voltage agrees qualitatively with the experimental curves.

[Dynamic theory of enzymatic catalysis]. / K dinamichesoi teorii fermentativnogo kataliza

Formal kinetics of an enzymatic reaction is considered in terms of a dynamic scheme of catalysis. Conformation reconstructions of a liberated enzyme and e-s-complex are analysed upon the phase plane. An expression for the enzyme stationary activity depending on the rate of conformation reconstructions is obtained. The case of purely dynamic catalysis is analysed and possible initiation of enzymatic activity variation in time connected with initial synchronization of molecules is shown. This phenomenon is considered as a possible criterion of the dynamic character of enzymatic catalysis.

[Rate of excitation propagation in a reduced Hodgkins-Huxley model. III. Integrodifferential equations]. / O skorosti rasprostraneniia vozbuzhdeniia v redutsirovannoi modeli Khodzhkina--Khaksli. III. Integrodifferentsial'noe uravenie

The Hodgkin - Huxley system of equations is reduced to single integral-differential equation in neglection of slow variables dynamics. Two limiting cases of fast and slow sodium activation processes are considered. The first case leads to a nonlinear differential equation for the potential, the second one - to an ordinary differential equation with a known source as a function of coordinate. Such a simplification is due to approximation of steady-state sodium activation variable with the help of Heviside function. The validity of this approximation is discussed; the corresponding error is estimated by calculation of the second approximation for the source function.

[Rate of excitation propagation in a reduced Hodgkins-Huxley model. II. Slow relaxation of the sodium current]. / O skorosti rasprostraneniia vozbuzhdeniia v redutsirovannoi modeli Khodzhkina--Khaksli. II. Medlennaia relaksatsii natrievogo toka

The influence of sodium current activation on the value of nerve excitation conduction velocity is investigated on the basis of Hodgkin-Huxley model. The potassium activation and sodium inactivation are considered as slow processes which do not develop to an appreciable extent in the region of conduction velocity formation. The system of equations was derived and solved analytically after neglecting the dependency of sodium relaxation time on potential; the approximation of steady-state sodium activation was also used with the help of Hevyside function. The algebraic equation for conduction velocity was obtained; its solution has a simple analytical form in two limits of rapid and slow sodium current relaxation. The comparison with the experimental data has shown that at not very high temperatures the slow (compared to the potential dynamics) sodium current relaxation approximation is more appropriate. The dependency of impulse velocity on capacitance and conductance of the fiber was analyzed.