Browsing by Author "Feldman, Yuri"
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Item Metadata only Amino Acids and Peptides(Oxford University Press, 2015-08) Ermolina, I.; Feldman, YuriThis chapter presents an overview of the dielectric properties of amino acids and oligopeptides in aqueous solutions. Two relaxation processes identified in the aqueous solutions of amino acids are ascribed to the molecular motion of the solute and water molecules. The relaxation characteristics (i.e., the dielectric strength and relaxation time) of the process related to amino acids strongly depend on the chemical nature (polar/charged/aromatic) and size of the side groups. The dielectric properties of water are changed by the presence of solute molecules. The relaxation process for water in amino acid solutions becomes wider in comparison with pure water and is well described by the phenomenological Cole–Cole spectral function. A discussion is also presented regarding the effect of molecular mass/length of chain and composition of the polypeptide, the pH of the solution and concentration on the dielectric properties of oligopeptides and polypeptide solutions. Finally, the mechanism of triple-helix-to-single-coil transition in model collagen polypeptides is discussed.Item Metadata only Analysis of Dielectric Spectra of Eucariotic Cells by Computer Modeling(Springer, 2000) Ermolina, I.; Polevaya, Yu; Feldman, YuriAn analysis of dielectric spectra, obtained by computer modeling, of spherical eukaryotic cells (lymphocytes in particular) is presented. The number of fitting parameters required to describe these spectra is determined. The in¯uence of parameter variation on the spectral shape is illustrated.Item Metadata only Analysis of error sources in time domain dielectric spectroscopy method(1992) Romanychev, G.; Ermolina, I.; Polygalov, E.; Zuev, Y.; Ubshincki, D. V.; Feldman, YuriItem Metadata only Automatic Time-Resolved Dielectric Spectrometer(Russian J. of Physical Chemistry ( Pleiades Publishing, Ltd.), 1987) Valitov, V. M.; Ermolina, I.; Zuev, Y.; Feldman, YuriItem Metadata only Computer controlled system for the measurement of dielectric parameters in time domain(1988) Valitov, V. M.; Ermolina, I.; Zuev, Y.; Feldman, YuriItem Metadata only Dielectric properties of bR membrane(ACS Publications, 2003-12-02) Ermolina, I.; Lewis, Aaron; Feldman, YuriThe application of dielectric spectroscopy (DS) to the study of bacteriorhodopsin (bR)-containing purple membrane films is presented in this paper. Two types of bR embrane films, oriented and nonoriented, were investigated in a wide frequency range (10-2-3 109 Hz) and temperature interval (5-70 °C). Four relaxation processes were observed in this frequency range and ascribed to different mechanisms, related to the structural units of the system. A large nonreversibility of the dielectric response as a result of heating and cooling has been observed in the slow processes implicating a change in the structure of the membrane stacking depending on the history of cooling and heating of the sample. Significant changes as large as 3 orders of magnitude in the mobility have been observed in this time scale. Comparison of the oriented and nonoriented bR embrane films was performed, and it was found that the oriented purple membrane has a unique liquid crystal-like ferroelectric behavior.Item Metadata only Dielectric relaxation measurements on 12 kbp plasmid DNA(Elsevier, 2000-09-06) Bakewell, D. J.; Ermolina, I.; Morgan, H.; Milner, J.; Feldman, YuriThe dielectric properties of 12 kbp plasmid DNA have been measured as a function of temperature in the range 5 degrees C to 40 degrees C. Time domain reflectometry was used to obtain dielectric data over the frequency range from 200 kHz to 3 GHz. Values of the frequency dependent polarisability per DNA macromolecule have been determined from the measurements. Possible mechanisms that could account for the dielectric dispersion are also discussed, in particular the counterion fluctuation model of Manning-Mandel-Oosawa.Item Metadata only Dielectric spectra broadening as a signature for dipole-matrix interaction. IV. Water in amino acids solutions(American Institute of Physics, 2014) Levy, Evgeniya; Cerveny, Silvina; Ermolina, I.; Puzenko, Alexander; Feldman, YuriItem Metadata only Dielectric Spectroscopy of Tobacco Mosaic Virus(Elsevier, 2003-06-11) Ermolina, I.; Morgan, H.; Green, N. G.; Milner, J. J.; Feldman, YuriThe dielectric properties of the Tobacco Mosaic Virus (TMV) have been measured using time domain dielectric spectroscopy (TDDS) in the temperature range from 1 to 40 oC. A single dielectric dispersion is observed in the MHz range. The activation energy of the process is found to be in the range 1–2 kcal/mol. The experimental data could not be completely accounted for by current theoretical models, but evidence indicates that the dielectric loss arises from polarisation of charge on and around the virus.Item Metadata only Difference method of analyzing dielectric data in the time domain(Russian J. of Physical Chemistry ( Pleiades Publishing, Ltd.), 1988) Feldman, Yuri; Zuev, Y.; Ermolina, I.; Goncharov, V. A.Item Metadata only Effect of penetration enhancers on the dynamic behavior of phosphatidylcholine headgroups in liposomes(ACS Publications, 2000-01-25) Ermolina, I.; Smith, G.; Ryabov, Y.; Puzenko, Alexander; Polevaya, Y; Nigmatullin, R. R.; Feldman, YuriThe results of a time-domain dielectric spectroscopy (TDDS) study of the effect of two skin penetration modulators on phosphatidylcholine (PC) bilayer vesicles are presented. The complex dielectric permittivity spectra of PC vesicle suspensions were described as the sum of two processes: the interfacial polarization of the bilayer and the reorientation of the zwitterionic PC headgroups in a plane approximately tangential to the bilayer surface. The influence of two additives (Azone and Transcutol) on the structure and dynamic behavior of PC headgroups of the bilayer vesicles was analyzed in terms of the interconnection of the dielectric spectra Cole−Davidson parameter, β, and the correlation factor, g, of the dielectric relaxation Kirkwood cell model. Analytically, these parameters are connected in the proposed model via the spatial distribution of headgroup dipole nonhomogeneities. In terms of the physical modulation of the polar surface phase, it appears that these additives can behave either as enhancers or as retarders. Their activity in this respect depends on the concentration of additive and temperature.Item Embargo Electrode polarization correction in Time Domain Dielectric Spectroscopy(IOP Science, 2001) Feldman, Yuri; Polygalov, E.; Ermolina, I.; Polevaya, Yu; Tsentsiper, B.Three methods of electrode polarization correction developed for time domain dielectric spectroscopy are reviewed in the paper. Two of them are based on the representation of the parasitic double electrical layer by an additional capacitor connected in series with the working electrodes of the sample holder. The third one takes into account the fractal nature of electrode polarization. The advantages and limitations of each method are discussed in the review.Item Metadata only Investigation of molecular motion and interprotein interactions in solutions by TDDS: A comparison with NMR data(Elsevier, 1994-09-01) Ermolina, I.; Fedotov,V.; Feldman, Yuri; Ivoylov, I.The results of dynamic protein behavior in solution studied by time domain dielectric spectroscopy (TDDS) are presented. The analyses for myoglobin solutions at concentrations 50, 120 and 150 mg/ml in the temperature interval from 5 to 35°C was carried out in terms of dipole correlation functions. It was found that the correlation function of the protein motion can be presented as a sum of three components corresponding to three types of protein motion: internal local motion, anisotropy otational Brownian diffusion and translational Brownian diffusion. According to the hypothesis presented earlier, it is supposed that the reason for anisotropy of protein rotation and capability for the detection translational diffusion (slowest motion) is the mutual interprotein electrostatic steering.Item Metadata only Investigation of molecular motions and interprotein interactions in solutions by NMR and TDDS.(Springer, 1993) Ermolina, I.; Krushelnitsky, A. G.; Ivoylov, I.; Feldman, Yuri; Fedotov, V.Non-selective NMR relaxation of protein and water protons at various resonance frequencies as well as Time Domain Dielectric Spectroscopy (TDDS) were applied to study the molecular motions in lysozyme and myoglobin solutions. It was found that the correlation function of the protein motion defined by means of all these methods can be presented as a sum of three components having substantially different correlation times. Both NMR and TDDS experimental data were treated on the basis of approach according to which these components of the correlation function correspond to three different kinds of protein motion, namely 1) internal local motion, 2) anisotropic rotational Brownian diffusion and 3) translational Brownian diffusion. According to the hypothesis proposed earlier we suppose that the reason of anisotropy of protein rotation and possibility to detect experimentally the slowest motion (translational diffusion) is the mutual interprotein electrostatic steering. The qualitative consistency between parameters of correlation function obtained from NMR and TDDS and their concentration dependence confirm the validity of the qualitative model of the interprotein electrostatic interactions.Item Metadata only NMR and dielectric spectroscopy investigation of protein dynamical structure(Elsevier, 1990-03) Fedotov, V.; Feldman, Yuri; Krushelnitsky, A. G.; Ermolina, I.The general approach to globular proteins dynamical structure investigation by NMR and time domain dielectric spectroscopy (TDDS) is presented. The information on macromolecular dynamical behavior in the case of these two methods is obtained in terms of correlation function and its parameters of atom motions. The interpretation of experimental results in the present work will be carried out in the framework of model-free approach which is common both for magnetic and dielectric relaxation. The lysozyme pH-dependence investigation is presented as an example.Item Metadata only Observation of Liquid-Crystal-Like Ferroelectric Behavior in a Biological Membrane(ACS Publications, 2001-03-16) Ermolina, I.; Lewis, Aaron; Feldman, Yuri; Strinkovski, Alinan this contribution, we report the application of time domain dielectric spectroscopy from 500 kHz to 1 GHz and differential scanning calorimetry to bacteriorhodopsin containing purple membrane films. The results of these measurements unexpectedly show that the oriented purple membrane has a unique liquid-crystal-like ferroelectric behavior. The dielectric behavior can be considered as soft mode relaxation processes in ferro-electric liquid crystals near smectic-C*−smectic-A phase transition. Such a phenomenon has not been previously observed in biological systems.Item Metadata only Proteins in Solutions and Natural Membranes(Oxford University Press, 2015-08) Ermolina, I.; Hayashi, Yoshihito; Raicu, Valerica; Feldman, YuriIn the first part of the chapter, dielectric spectroscopy studies of globular proteins in aqueous solutions in native and denatured states are reviewed. Here we discuss the mechanisms of two major dielectric relaxation processes (γ- and β-dispersions) and one minor process (δ-dispersion) observed in the diluted globular protein solutions. Effects of protein concentration, temperature, pH, and denaturants were also summarized. The second part of the chapter presents the dielectric properties of proteins in natural membrane fragments and living cells membrane. Ferroelectric behavior was observed for the first time for the package of bacteriorhodopsin membrane fragments oriented in the electric field. Here, a discussion is also presented about progress and problems related to the observation of proteins in living cells using dielectric spectroscopyItem Open Access Study of normal and malignant white blood cells by time domain dielectric spectroscopy.(IEEE, 2001-04-01) Ermolina, I.; Polevaya, Y.; Ginzburg, B.; Schlesinger, M.; Feldman, YuriThe aim of this paper is to present a comprehensive theoretical and experimental study by means of time domain dielectric spectrometer (TDDS) of static and dynamic dielectric properties of normal and malignant blood cells. The successful use of the TDDS method as a tool of human cell study required a special protocol and algorithms for all stages of cell preparation, measurements and data treatment. The routine developed in this study was used in the experimental analysis of nine lines of malignant, transformed and normal lymphocytes. It was shown that dielectric permittivity, capacitance and conductivity values of the cell membrane are higher for normal lymphocytes in comparison with malignant ones.Item Metadata only Study of the Dynamic Structure of Native and Hydrophobized Glucose Oxidase by Time-Domain Dielectric Spectroscopy(ACS Publications, 2000-07-26) Kamyshny, A.; Ermolina, I.; Magdassi, S.; Feldman, YuriThe dynamic structures of native and hydrophobized (by covalent attachment of palmitoyl chains) glucose oxidase were studied by time-domain dielectric spectroscopy (TDDS). Analysis of the dipole correlation function for both types of the enzyme showed that the decay of the correlation function of the macromolecule motion can be presented as a sum of components corresponding to different kinds of protein motion: isotropic rotation of the protein molecule as a whole, anisotropic Brownian tumbling of subunits, and anisotropic intramolecular motion of polar groups and substructures. The slowest relaxation time was found to be longer for the modified enzyme than for the native enzyme. The dielectric strengths for all relaxation processes, as well as the dipole moment and the molecular volume, were also larger for the modified glucose oxidase. The observed differences between various types of the dipole motion for the native and modified glucose oxidase are discussed.Item Embargo Time Domain Dielectric Spectroscopy Study of Biological Systems(IEEE, 2003) Feldman, Yuri; Ermolina, I.; Hayashi, YoshihitoThe main principles of time domain dielectric spectroscopy, its application to conductive systems and possible methods of electrode polarization corrections in time domain are introduced. A comprehensive theoretical and experimental study of static and dynamic dielectric properties of different biological systems including globular and membrane proteins, hydrate water, human erythrocytes, and normal and malignant blood cells of different types is presented in the paper.