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Hu K, Matsuura H, Shirakashi R. Stochastic Analysis of Molecular Dynamics Reveals the Rotation Dynamics Distribution of Water around Lysozyme. J Phys Chem B 2022; 126:4520-4530. [PMID: 35675630 DOI: 10.1021/acs.jpcb.2c00970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Water dynamics is essential to biochemical processes by mediating all such reactions, including biomolecular degeneration in solutions. To disentangle the molecular-scale distribution of water dynamics around a solute biomolecule, we investigated here the rotational dynamics of water around lysozyme by combining molecular dynamics (MD) simulations and broadband dielectric spectroscopy (BDS). A statistical analysis using the relaxation times and trajectories of every single water molecule was proposed, and the two-dimensional probability distribution of water at a distance from the lysozyme surface with a rotational relaxation time was given. For the observed lysozyme solutions of 34-284 mg/mL, we discovered that the dielectric relaxation time obtained from this distribution agrees well with the measured γ relaxation time, which suggests that rotational self-correlation of water molecules underlies the gigahertz domain of the dielectric spectra. Regardless of protein concentration, water rotational relaxation time versus the distance from the lysozyme surface revealed that the water rotation is severely retarded within 3 Å from the lysozyme surface and is nearly comparable to pure water when farther than 10 Å. The dimension of the first hydration layer was subsequently identified in terms of the relationship between the acceleration of water rotation and the distance from the protein surface.
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Affiliation(s)
- Kang Hu
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro City, Tokyo 153-8505, Japan.,Department of Mechanical Engineering, The University of Tokyo, 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroaki Matsuura
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro City, Tokyo 153-8505, Japan.,Research Fellow of the Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo 102-0083, Japan
| | - Ryo Shirakashi
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro City, Tokyo 153-8505, Japan
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2
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Latypova L, Puzenko A, Levy E, Feldman Y. Dielectric spectra broadening as a signature for dipole–matrix interactions. V. Water in protein solutions. J Chem Phys 2020; 153:045102. [DOI: 10.1063/5.0016437] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Larisa Latypova
- Department of Applied Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
- Department of Physics, Kazan Federal University, 18 Kremlewskaya St., 420008 Kazan, Russia
| | - Alexander Puzenko
- Department of Applied Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Evgeniya Levy
- Department of Applied Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Yuri Feldman
- Department of Applied Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
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3
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Siwach P, Levy E, Livshits L, Feldman Y, Kaganovich D. Water is a biomarker of changes in the cellular environment in live animals. Sci Rep 2020; 10:9095. [PMID: 32499602 PMCID: PMC7272622 DOI: 10.1038/s41598-020-66022-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 05/12/2020] [Indexed: 11/09/2022] Open
Abstract
The biological processes that are associated with the physiological fitness state of a cell comprise a diverse set of molecular events. Reactive oxygen species (ROS), mitochondrial dysfunction, telomere shortening, genomic instability, epigenetic changes, protein aggregation, and down-regulation of quality control mechanisms are all hallmarks of cellular decline. Stress-related and decline-related changes can be assayed, but usually through means that are highly disruptive to living cells and tissues. Biomarkers for organismal decline and aging are urgently needed for diagnostic and drug development. Our goal in this study is to provide a proof-of-concept for a non-invasive assay of global molecular events in the cytoplasm of living animals. We show that Microwave Dielectric Spectroscopy (MDS) can be used to determine the hydration state of the intracellular environment in live C. elegans worms. MDS spectra were correlative with altered states in the cellular protein folding environment known to be associated with previously described mutations in the C. elegans lifespan and stress-response pathways.
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Affiliation(s)
- Pratibha Siwach
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Walweg 33, 37073, Göttingen, Germany
| | - Evgeniya Levy
- Department of Applied Physics, The Hebrew University of Jerusalem, Edmond J Safra campus, 919041, Jerusalem, Israel
| | - Leonid Livshits
- Vetsuisse Faculty, Institute of Veterinary Physiology, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland
| | - Yuri Feldman
- Department of Applied Physics, The Hebrew University of Jerusalem, Edmond J Safra campus, 919041, Jerusalem, Israel
| | - Daniel Kaganovich
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Walweg 33, 37073, Göttingen, Germany.
- 1Base Pharmaceuticals, Boston, MA, 02129, USA.
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4
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Li Z, Voth GA. Interfacial solvation and slow transport of hydrated excess protons in non-ionic reverse micelles. Phys Chem Chem Phys 2020; 22:10753-10763. [PMID: 32154815 DOI: 10.1039/d0cp00378f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This work employs molecular dynamics simulations to investigate the solvation and transport properties of hydrated excess protons (with a hydronium-like core structure) in non-ionic Igepal CO-520 reverse micelles of various sizes in a non-polar solvent. Multiscale Reactive Molecular Dynamics (MS-RMD) simulations were used to describe vehicular and hopping diffusion during the proton transport process. As detailed herein, an excess proton shows a marked tendency to localize in the interfacial region of micellar water pools. Slow proton transport was observed which becomes faster with increasing micellar size. Further analysis reveals that the slow diffusion of an excess proton is a combined result of slow water diffusion and the low proton hopping rate. This study also confirms that a low proton hopping rate in reverse micelles stems from the interfacial solvation of hydrated excess protons and the immobilization of interfacial water. The low water density in the interfacial region makes it difficult to form a complete hydrogen bond network near the hydrated excess proton, and therefore locks in the orientation of hydrated proton cations. The immobilization of the interfacial water also slows the relaxation of the overall hydrogen bond network.
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Affiliation(s)
- Zhefu Li
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, USA.
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5
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Contribution of Proteins to the Dielectric Properties of Dielectrically Heated Biomaterials. FOOD BIOPROCESS TECH 2017. [DOI: 10.1007/s11947-017-1920-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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6
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Wolf M, Emmert S, Gulich R, Lunkenheimer P, Loidl A. Dynamics of protein hydration water. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:032727. [PMID: 26465518 DOI: 10.1103/physreve.92.032727] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Indexed: 06/05/2023]
Abstract
We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures, and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range. The obtained results prove the bimodality of the hydration shell dynamics. In addition, we find indications of a fragile-to-strong transition of hydration water.
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Affiliation(s)
- M Wolf
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Universitätsstr. 2, 86135 Augsburg, Germany
| | - S Emmert
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Universitätsstr. 2, 86135 Augsburg, Germany
| | - R Gulich
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Universitätsstr. 2, 86135 Augsburg, Germany
| | - P Lunkenheimer
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Universitätsstr. 2, 86135 Augsburg, Germany
| | - A Loidl
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Universitätsstr. 2, 86135 Augsburg, Germany
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7
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Ryabov Y. Coupling between overall rotational diffusion and domain motions in proteins and its effect on dielectric spectra. Proteins 2015; 83:1571-81. [PMID: 25900685 DOI: 10.1002/prot.24814] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/23/2015] [Accepted: 04/05/2015] [Indexed: 11/08/2022]
Abstract
In this work, we formulate a closed-form solution of the model of a semirigid molecule for the case of fluctuating and reorienting molecular electric dipole moment. We illustrate with numeric calculations the impact of protein domain motions on dielectric spectra using the example of the 128 kDa protein dimer of Enzyme I. We demonstrate that the most drastic effect occurs for situations when the characteristic time of protein domain dynamics is comparable to the time of overall molecular rotational diffusion. We suggest that protein domain motions could be a possible explanation for the high-frequency contribution that accompanies the major relaxation dispersion peak in the dielectric spectra of protein aqueous solutions. We propose that the presented computational methodology could be used for the simultaneous analysis of dielectric spectroscopy and nuclear magnetic resonance data. Proteins 2015; 83:1571-1581. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Yaroslav Ryabov
- BC Portal Inc., 260 Congressional Ln. #204, Rockville, Maryland, 20852
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8
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Ghosh R, Banerjee S, Hazra M, Roy S, Bagchi B. Sensitivity of polarization fluctuations to the nature of protein-water interactions: Study of biological water in four different protein-water systems. J Chem Phys 2014; 141:22D531. [DOI: 10.1063/1.4902821] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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9
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Wolf M, Gulich R, Lunkenheimer P, Loidl A. Relaxation dynamics of a protein solution investigated by dielectric spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:723-30. [DOI: 10.1016/j.bbapap.2012.02.008] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 01/31/2012] [Accepted: 02/22/2012] [Indexed: 11/30/2022]
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10
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Abou-Aiad T, Becker U, Biedenkap R, Brengelmann R, Elsebrock R, Hinz HJ, Stockhausen M. Dielectric relaxation of aqueous solutions of ribonuclease A in the absence and presence of urea. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19971011219] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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Dachwitz E, Parak F, Stockhausen M. On the Dielectric Relaxation of Aqueous Myoglobin Solutions. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19890931213] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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12
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Gunda NSK, Mitra SK. Modeling of dielectrophoretic transport of myoglobin molecules in microchannels. BIOMICROFLUIDICS 2010; 4:14105. [PMID: 20644674 PMCID: PMC2905271 DOI: 10.1063/1.3339773] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 02/08/2010] [Indexed: 05/20/2023]
Abstract
Myoglobin is one of the premature identifying cardiac markers, whose concentration increases from 90 pgml or less to over 250 ngml in the blood serum of human beings after minor heart attack. Separation, detection, and quantification of myoglobin play a vital role in revealing the cardiac arrest in advance, which is the challenging part of ongoing research. In the present work, one of the electrokinetic approaches, i.e., dielectrophoresis (DEP), is chosen to separate the myoglobin. A mathematical model is developed for simulating dielectrophoretic behavior of a myoglobin molecule in a microchannel to provide a theoretical basis for the above application. This model is based on the introduction of a dielectrophoretic force and a dielectric myoglobin model. A dielectric myoglobin model is developed by approximating the shape of the myoglobin molecule as sphere, oblate, and prolate spheroids. A generalized theoretical expression for the dielectrophoretic force acting on respective shapes of the molecule is derived. The microchannel considered for analysis has an array of parallel rectangular electrodes at the bottom surface. The potential and electric field distributions are calculated using Green's theorem method and finite element method. These results also compared to the Fourier series method, closed form solutions by Morgan et al. [J. Phys. D: Appl. Phys. 34, 1553 (2001)] and Chang et al. [J. Phys. D: Appl. Phys. 36, 3073 (2003)]. It is observed that both Green's theorem based analytical solution and finite element based numerical solution for proposed model are closely matched for electric field and square electric field gradients. The crossover frequency is obtained as 40 MHz for given properties of myoglobin and for all approximated shapes of myoglobin molecule. The effect of conductivity of medium and myoglobin on the crossover frequency is also demonstrated. Further, the effect of hydration layer on the crossover frequency of myoglobin molecules is also presented. Both positive and negative DEP effects on myoglobin molecules are obtained by switching the frequency of applied electric field. The effect of different shapes of myoglobin on DEP force is studied and no significant effect on DEP force is observed. Finally, repulsion of myoglobin molecules from the electrode plane at 1 KHz frequency and 10 V applied voltage is observed. These results provide the ability of applying DEP force for manipulating nanosized biomolecules such as myoglobin.
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Affiliation(s)
- Naga Siva Kumar Gunda
- Department of Mechanical Engineering, Micro and Nano-scale Transport Laboratory, University of Alberta, Edmonton T6G 2G8, Canada
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13
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Polar and Nonpolar Solvation Dynamics, Ion Diffusion, and Vibrational Relaxation: Role of Biphasic Solvent Response in Chemical Dynamics. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141687.ch4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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14
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Abstract
The interaction of proteins with an aqueous environment leads to a thin region of "biological water", the molecules of which have properties that differ from those of bulk water, in particular, reduced absorption of far-infrared radiation caused by protein-induced hindrance of the water rotational and vibrational degrees of freedom. New results at terahertz (THz) frequencies, however, show that absorption per protein molecule is increased by the presence of biological water. Absorption measurements were made of the heme protein myoglobin mixed with water from 3.6 to 98 wt % in the frequency range of 0.1-1.2 THz, using THz time-domain spectroscopy. Analysis shows greater THz absorption when compared to a non-interacting protein-water model. Including the suppressed absorption of biological water leads to a substantial hydration-dependent increase in absorption per protein molecule over a wide range of concentration and frequencies, meaning that water increases the protein's polarizability.
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Affiliation(s)
- Chenfeng Zhang
- Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA
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15
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Rodríguez M, Lindinger A, Pérez Lustres JL, Kovalenko SA, Ernsting NP, Wöste L, Siegel G. Femtosecond dynamics of proteoheparan sulfate (HS-PG) after UV excitation—A readout for arteriosclerotic nanoplaque formation? Biochem Biophys Res Commun 2006; 345:886-93. [PMID: 16707112 DOI: 10.1016/j.bbrc.2006.04.164] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Accepted: 04/26/2006] [Indexed: 11/18/2022]
Abstract
Ultrashort UV laser pulses were used to excite tryptophan residues of heparan sulfate proteoglycan (HS-PG) in blood substitute Krebs solution. Tryptophan fluorescence is sensitive to the environment, so its shift and decay indicate the conformation and solvation state of the protein. We monitored stimulated emission and excited-state absorption by probing with delayed white-light femtosecond pulses. Comparison with bare tryptophan revealed transient absorption features which are characteristic for HS-PG. Furthermore, the effect of adding calcium salt was investigated. Differences in the spectra from solutions with and without calcium developed during several minutes, which points to changes in protein conformation, but could only be measured in the sub-ps regime. These results provide a first step to a better understanding of the molecular formation of nanoplaques in blood vessels. The goal of this work is to open a way towards biosensing of the initial stages in atherogenesis allowing for a risk assessment in cardiovascular disease.
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Affiliation(s)
- Miguel Rodríguez
- Institut für Physiologie, Charité-Universitätsmedizin Berlin, 14195 Berlin, Germany.
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16
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Tryptophan–water interaction in Monellin: Hydration patterns from molecular dynamics simulation. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.01.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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17
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Simeonova M, Gimsa J. The influence of the molecular structure of lipid membranes on the electric field distribution and energy absorption. Bioelectromagnetics 2006; 27:652-66. [PMID: 16917873 DOI: 10.1002/bem.20259] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We consider the influence of the molecular structure of phospholipid membranes on their dielectric properties in the radio frequency range. Membranes have a stratified dielectric structure on the submolecular level, with the lipid chains forming a central hydrophobic layer enclosed by the polar headgroups (HGs) and bound water layers. In our numerical model, isotropic permittivities of 2.2 and 48.8 were assigned to the lipid chain and bound water layers, respectively. The HG region was assumed to possess an anisotropic static permittivity with 142.2 and 30.2 in the tangential and normal directions, respectively. The permittivities of the HG and bound water regions have been assumed to disperse at frequencies around 51 and 345 MHz to become 2.2 and 1.8, respectively, in both the normal and tangential directions. Electric field distribution and absorption were calculated for phospholipid vesicles with 75 nm radius as an example. Significant absorption has been obtained in the HG and bound water regions. Averaging the membrane absorption over the layers resulted in a decreased absorption below 1 GHz but a more than 10-fold increase above 1 GHz, compared to a model with a homogeneous membrane of averaged properties. We propose single particle dielectric spectroscopy by AC electrokinetics at low-bulk medium conductivities for an experimental verification of our model.
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Affiliation(s)
- Margarita Simeonova
- Department of Biology, University of Rostock, Chair of Biophysics, Rostock, Germany
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18
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Affiliation(s)
- Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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19
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Mennucci B, Martínez JM. How to Model Solvation of Peptides? Insights from a Quantum-mechanical and Molecular Dynamics Study ofN-Methylacetamide. 1. Geometries, Infrared, and Ultraviolet Spectra in Water. J Phys Chem B 2005; 109:9818-29. [PMID: 16852182 DOI: 10.1021/jp050034z] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This paper represents the first part of a study of solvation in peptides using quantum-mechanical and classical approaches. In this study, the peptide is modeled as its simplest analogue, namely, N-methyl-acetamide, and the effects of the solvent (here water, and in the second part of the study, water and acetone) are introduced at three different levels, e.g., through a continuum description, using solute-solvent clusters, and using the same clusters embedded in an external continuum. In turn, the solute-solvent clusters have been obtained in two alternative ways, either by using QM optimization procedures or extracting a proper set of structures from MD simulations. In this part of the study, geometries, IR, and UV spectra are calculated in terms of the different solvation models, and the results are analyzed and compared to get insights about different aspects of solvation involving dynamic and static effects on one hand and bulk or specific interactions on the other hand.
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Affiliation(s)
- Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento 35, 56126 Pisa, Italy.
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20
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Vanderstraeten J, Vander Vorst A. Theoretical evaluation of dielectric absorption of microwave energy at the scale of nucleic acids. Bioelectromagnetics 2004; 25:380-9. [PMID: 15197763 DOI: 10.1002/bem.20001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A theoretical model is proposed for the evaluation of dielectric properties of the cell nucleus between 0.3 and 3 GHz, as a function of its nucleic acids (NA) concentration (CNA). It is based on literature data on dielectric properties of DNA solutions and nucleoplasm. In skeletal muscle cells, the specific absorption rate (SAR) ratio between nucleoplasm and cytoplasm is found to be larger than one for CNA above 30 mg/ml. A nearly linear relationship is found between CNA and this nucleocytoplasmic SAR ratio. Considering the nanoscale of the layer of condensed counterions and bound water molecules at the NA-solution interface, the power absorption per unit volume is evaluated at this precise location. It is found to be between one and two orders of magnitude above that in muscle tissue as a whole. Under realistic microwave (MW) exposure conditions, however, these SAR inhomogeneities do not generate any significant thermal gradient at the scale considered here. Nevertheless, the question arises of a possible biological relevance of nonnegligible and preferential heat production at the location of the cell nucleus and of the NA molecules.
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Bandyopadhyay S, Chakraborty S, Balasubramanian S, Pal S, Bagchi B. Atomistic Simulation Study of the Coupled Motion of Amino Acid Residues and Water Molecules around Protein HP-36: Fluctuations at and around the Active Sites. J Phys Chem B 2004. [DOI: 10.1021/jp048532f] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sanjoy Bandyopadhyay
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India, and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Sudip Chakraborty
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India, and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Sundaram Balasubramanian
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India, and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Subrata Pal
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India, and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Biman Bagchi
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India, and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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22
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Senapati S, Berkowitz ML. Computer Simulation Studies of Water States in Perfluoro Polyether Reverse Micelles: Effects of Changing the Counterion. J Phys Chem A 2004. [DOI: 10.1021/jp048954p] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sanjib Senapati
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Max L. Berkowitz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Dastidar SG, Mukhopadhyay C. Structure, dynamics, and energetics of water at the surface of a small globular protein: a molecular dynamics simulation. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:021921. [PMID: 14525020 DOI: 10.1103/physreve.68.021921] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Indexed: 05/24/2023]
Abstract
The dynamics of water around a biomolecular surface has attracted a lot of attention recently. We report here protein-solvent simulation studies of the small globular protein ubiquitin (human). The simulations are run unconstrained, without freezing the bonds. The mean square displacements of the water oxygen atoms show a sublinear trend with time. The diffusion coefficient data indicate that the water in the first hydration layer behaves like water at a temperature that is roughly 12 degrees C lower than the average temperature of the system (27 degrees C). Both the dipolar second-rank relaxation and the survival time correlation function of the water layers show two decay constants, indicating contributions from fast and slow dynamics. A calculation of the interaction energy between the water layers and protein indicates that the interaction energy sharply decreases beyond 4 A from the protein surface.
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Affiliation(s)
- Shubhra Ghosh Dastidar
- Department of Chemistry, University of Calcutta, 92. A.P.C. Road, Kolkata, 700 009, India
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24
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Senapati S, Berkowitz ML. Water structure and dynamics in phosphate fluorosurfactant based reverse micelle: A computer simulation study. J Chem Phys 2003. [DOI: 10.1063/1.1531585] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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25
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Bagchi B. 5 Water solvation dynamics in the bulk and in the hydration layer of proteins and self-assemblies. ACTA ACUST UNITED AC 2003. [DOI: 10.1039/b208505b] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Yoshiba K, Ishino T, Teramoto A, Nakamura N, Miyazaki Y, Sorai M, Wang Q, Hayashi Y, Shinyashiki N, Yagihara S. Ordering in aqueous polysaccharide solutions. II. Optical rotation and heat capacity of aqueous solutions of a triple-helical polysaccharide schizophyllan. Biopolymers 2002; 63:370-81. [PMID: 11920438 DOI: 10.1002/bip.10129] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Deuterium oxide solutions of schizophyllan, a triple-helical polysaccharide, undergoing an order-disorder transition centered at 17 degrees C, were studied by optical rotation (OR) and heat capacity (C(p)) to elucidate the molecular mechanism of the transition and water structure in the solution and frozen states. The ordered structure at low temperature consisted of the side chains and water in the vicinity forming an ordered hydrogen-bonded network surrounding the helix core and was disordered at higher temperature. In the solution state appeared clearly defined transition curves in both the OR and C(p) data. The results for three samples of different molecular weights were analyzed theoretically, treating this transition as a typical linear cooperative transition from the ordered to disordered states and explained quantitatively if the molecular weight polydispersity of the sample was considered. The excess heat capacity C(EX)(p) defined as the C(p) minus the contributions from schizophyllan and D(2)O was estimated. In the frozen state it increased with raising temperature above 150 K until the mixture melted. This was compared with the dielectric increment observed in this temperature range and ascribed to unfreezable water. From the heat capacity and dielectric data, unfreezable water is mobile but more ordered than free water. In the solution state, the excess heat capacity originates from the interactions of D(2)O molecules as bound water and structured water, and so forth. Thus the schizophyllan triple helix molds water into various structures of differing orders in solution and in the solid state.
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Affiliation(s)
- Kazuto Yoshiba
- Department of Applied Chemistry, Faculty of Science and Engineering, Ritsumeikan University, Nojihigashi 1-1-1, Kusatsu, Siga 525-8577, Japan
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Pal SK, Peon J, Zewail AH. Biological water at the protein surface: dynamical solvation probed directly with femtosecond resolution. Proc Natl Acad Sci U S A 2002; 99:1763-8. [PMID: 11842218 PMCID: PMC122267 DOI: 10.1073/pnas.042697899] [Citation(s) in RCA: 418] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Biological water at the interface of proteins is critical to their equilibrium structures and enzyme function and to phenomena such as molecular recognition and protein-protein interactions. To actually probe the dynamics of water structure at the surface, we must examine the protein itself, without disrupting the native structure, and the ultrafast elementary processes of hydration. Here we report direct study, with femtosecond resolution, of the dynamics of hydration at the surface of the enzyme protein Subtilisin Carlsberg, whose single Trp residue (Trp-113) was used as an intrinsic biological fluorescent probe. For the protein, we observed two well separated dynamical solvation times, 0.8 ps and 38 ps, whereas in bulk water, we obtained 180 fs and 1.1 ps. We also studied a covalently bonded probe at a separation of approximately 7 A and observed the near disappearance of the 38-ps component, with solvation being practically complete in (time constant) 1.5 ps. The degree of rigidity of the probe (anisotropy decay) and of the water environment (protein vs. micelle) was also studied. These results show that hydration at the surface is a dynamical process with two general types of trajectories, those that result from weak interactions with the selected surface site, giving rise to bulk-type solvation (approximately 1 ps), and those that have a stronger interaction, enough to define a rigid water structure, with a solvation time of 38 ps, much slower than that of the bulk. At a distance of approximately 7 A from the surface, essentially all trajectories are bulk-type. The theoretical framework for these observations is discussed.
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Affiliation(s)
- Samir Kumar Pal
- Laboratory for Molecular Sciences, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
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28
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Hayashi Y, Shinyashiki N, Yagihara S, Yoshiba K, Teramoto A, Nakamura N, Miyazaki Y, Sorai M, Wang Q. Ordering in aqueous polysaccharide solutions. I. Dielectric relaxation in aqueous solutions of a triple-helical polysaccharide schizophyllan. Biopolymers 2002; 63:21-31. [PMID: 11754345 DOI: 10.1002/bip.1059] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Deuterium oxide solutions of a triple-helical polysaccharide schizophyllan, undergoing an order-disorder transition centered around 17 degrees C, were studied by the time-domain reflectometry (TDR) to obtain dielectric dispersions in the solution and frozen states. In the solution state, the dispersion below the transition temperature is resolved in three dispersions (relaxation times at 0 degrees C) ascribed to side chain glucose residue (1; 102 ns), structured water (s; 2.0 ns) and bulk water (h), respectively, from low to high frequencies. Bulk water is divided into slow water (h2; 0.04 ns) and free or pure water (h1; 0.02 ns). Above the transition temperature structured water almost disappears and is compensated by slow water. Structured water is similar to bound water for proteins but different from it because of this transition behavior. Another dispersion (l) seen at the lowest frequency is assigned to the rotation of side-chain glucose residue coupled with hydrated water. Parts of this dispersion and structured water are suggested to constitute bound water. In the frozen state were observed a major dispersion (h; 0.14 ns) and a minor one (m; 28 ns), which were ascribed to considerably mobile and less mobile waters. They are similar to but not exactly the same as that for unfreezable water in bovine serum albumin solutions argued by Miura et al. (Biopolymers, 1995, Vol. 36, p. 9). Water is molded into different structures by the triple helix.
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Affiliation(s)
- Yoshihito Hayashi
- Department of Physics, Faculty of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-12, Japan
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29
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Hayashi Y, Miura N, Shinyashiki N, Yagihara S, Mashimo S. Globule-coil transition of denatured globular protein investigated by a microwave dielectric technique. Biopolymers 2000; 54:388-97. [PMID: 10951325 DOI: 10.1002/1097-0282(200011)54:6<388::aid-bip30>3.0.co;2-k] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A mechanism for the gel-glass transition of denatured globular protein has been explained from the viewpoint of the globule-coil transition with microwave dielectric measurements using a time domain reflectometry (TDR) method. Boiled egg white, which is an aqueous gel of egg white prepared by heat treatment at 100 degrees C, becomes a glass on drying. In the gel state, the relaxation processes corresponding to the orientation of bulk water and the micro-Brownian motion of peptide chains of denatured protein were observed around 10 GHz and 10 MHz, respectively. When the gel-glass transition occurred, the relaxation strength for bulk water decreased rapidly as evaporation and breaking of water structure occurred. Simultaneously, the relaxation strength for micro-Brownian motion increased abruptly, as the structure of globular protein varied from globule state to coiled state. It is considered that the protein molecule spreads out and takes up a coiled state by reductions of hydrophobic and hydrophilic interactions of the globular protein. These reductions occur through a decrease in the amount of water.
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Affiliation(s)
- Y Hayashi
- Department of Physics, Tokai University, Hiratsuka-shi, Kanagawa, 259-1292, Japan
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30
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Kamyshny A, Ermolina I, Magdassi S, Feldman Y. Study of the Dynamic Structure of Native and Hydrophobized Glucose Oxidase by Time-Domain Dielectric Spectroscopy. J Phys Chem B 2000. [DOI: 10.1021/jp992454s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Kamyshny
- Casali Institute of Applied Chemistry, and Department of Applied Physics, School of Applied Science, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - I. Ermolina
- Casali Institute of Applied Chemistry, and Department of Applied Physics, School of Applied Science, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - S. Magdassi
- Casali Institute of Applied Chemistry, and Department of Applied Physics, School of Applied Science, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Yu. Feldman
- Casali Institute of Applied Chemistry, and Department of Applied Physics, School of Applied Science, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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31
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Nandi N, Bhattacharyya K, Bagchi B. Dielectric relaxation and solvation dynamics of water in complex chemical and biological systems. Chem Rev 2000; 100:2013-46. [PMID: 11749282 DOI: 10.1021/cr980127v] [Citation(s) in RCA: 688] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N Nandi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India
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Affiliation(s)
- Nilashis Nandi
- Department of Chemistry, Faculty of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-01, Japan
| | - Biman Bagchi
- Department of Chemistry, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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33
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Affiliation(s)
- Nilashis Nandi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India 560012
| | - Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India 560012
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34
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Gimsa J, Müller T, Schnelle T, Fuhr G. Dielectric spectroscopy of single human erythrocytes at physiological ionic strength: dispersion of the cytoplasm. Biophys J 1996; 71:495-506. [PMID: 8804632 PMCID: PMC1233500 DOI: 10.1016/s0006-3495(96)79251-2] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Usually dielectrophoretic and electrorotation measurements are carried out at low ionic strength to reduce electrolysis and heat production. Such problems are minimized in microelectrode chambers. In a planar ultramicroelectrode chamber fabricated by semiconductor technology, we were able to measure the dielectric properties of human red blood cells in the frequency range from 2 kHz to 200 MHz up to physiological ion concentrations. At low ionic strength, red cells exhibit a typical electrorotation spectrum with an antifield rotation peak at low frequencies and a cofield rotation peak at higher ones. With increasing medium conductivity, both electrorotational peaks shift toward higher frequencies. The cofield peak becomes antifield for conductivities higher than 0.5 S/m. Because the polarizability of the external medium at these ionic strengths becomes similar to that of the cytoplasm, properties can be measured more sensitively. The critical dielectrophoretic frequencies were also determined. From our measurements, in the wide conductivity range from 2 mS/m to 1.5 S/m we propose a single-shell erythrocyte model. This pictures the cell as an oblate spheroid with a long semiaxis of 3.3 microns and an axial ratio of 1:2. Its membrane exhibits a capacitance of 0.997 x 10(-2) F/m2 and a specific conductance of 480 S/m2. The cytoplasmic parameters, a conductivity of 0.4 S/m at a dielectric constant of 212, disperse around 15 MHz to become 0.535 S/m and 50, respectively. We attribute this cytoplasmic dispersion to hemoglobin and cytoplasmic ion properties. In electrorotation measurements at about 60 MHz, an unexpectedly low rotation speed was observed. Around 180 MHz, the speed increased dramatically. By analysis of the electric chamber circuit properties, we were able to show that these effects are not due to cell polarization but are instead caused by a dramatic increase in the chamber field strength around 180 MHz. Although the chamber exhibits a resonance around 180 MHz, the harmonic content of the square-topped driving signals generates distortions of electrorotational spectra at far lower frequencies. Possible technological applications of chamber resonances are mentioned.
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Affiliation(s)
- J Gimsa
- Institute of Biology, Humboldt-University, Berlin, Germany. jan=
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35
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Teramoto A, Gu H, Miyazaki Y, Sorai M, Mashimo S. Dielectric study of the cooperative order-disorder transition in aqueous solutions of schizophyllan, a triple-helical polysaccharide. Biopolymers 1995; 36:803-10. [PMID: 8555424 DOI: 10.1002/bip.360360612] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Schizophyllan exists in aqueous solution as a triple helix, which is intact at room temperature. Its aqueous solution forms some ordered structure at low temperatures but undergoes a sharp transition to a disordered structure as the temperature is raised. The transition temperature Tc is about 7 and 18 degrees C for H2O and D2O solutions, respectively. This transition was followed by time-domain reflectometry to investigate dynamic aspects of the transition. In addition to a major peak around 10 GHz, the dielectric dispersion curve of a 20 wt % schizophyllan in D2O exhibited a small peak around 100 MHz below Tc and around 10 MHz above Tc. The major peak is due to bulk water, whereas the 100 MHz peak is assigned to "bound" or "structured" water, and that around 10 MHz to side-chain glucose residues. However, unlike usual bound water reported for biopolymer solutions, this "structured" water disappears abruptly when the temperature becomes close to Tc without accompanying a conformational transition of the main chain. The above assignment is consistent with the structure of the ordered phase derived from previous static data that it consists of side-chain glucose residues along with nearby water molecules surrounding the helix core that are interacting with each other loosely through hydrogen bonds, and spreads radially only a layer of one or two water molecules but a long distance along the helix axis.
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Affiliation(s)
- A Teramoto
- Department of Macromolecular Science, Osaka University, Japan
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36
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Yoshioka S, Aso Y, Otsuka T, Kojima S. Water mobility in poly(ethylene glycol)-, poly(vinylpyrrolidone)-, and gelatin-water systems, as indicated by dielectric relaxation time, spin-lattice relaxation time, and water activity. J Pharm Sci 1995; 84:1072-7. [PMID: 8537884 DOI: 10.1002/jps.2600840908] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The mobility of water molecules present in poly(ethylene glycol) (PEG)-, poly(vinylpyrrolidone) (PVP)-, and gelatin-water systems was determined by dielectric relaxation and 17O NMR spectroscopy. Water activity was also measured. Dielectric relaxation spectra indicate that all the polymer systems studied contained water exhibiting a dispersion at a frequency > 10(9) Hz; in other words, water with high mobility close to that of bulk water. The dielectric relaxation time of the highly mobile water increased as polymer concentration increased. The PVP- and gelatin-water systems also contained water exhibiting a dispersion at a frequency < 10(9) Hz, which can be considered to be "bound water" with a restricted mobility because of its association with polymer molecules. Dielectric relaxation spectroscopy was used to determine water mobility separately for the populations of highly mobile water and bound water, whereas NMR relaxation spectroscopy was used to determine the average mobility of both populations. The spin-lattice relaxation time of water in these polymer-water systems showed a deviation from the isotropic two-state model. Dielectric relaxation data indicate that this deviation can be ascribed to variations in the relaxation time of highly mobile water caused by a change in polymer concentration. The dielectric relaxation time of highly mobile water in the gelatin system did not change with a change in polymer concentration to the extent that it did in the PEG and PVP systems. This result is consistent with a slight change in water activity of the gelatin system with increasing polymer concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Yoshioka
- National Institute of Health Sciences, Tokyo, Japan
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37
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Smith G, Duffy AP, Shen J, Olliff CJ. Dielectric relaxation spectroscopy and some applications in the pharmaceutical sciences. J Pharm Sci 1995; 84:1029-44. [PMID: 8537878 DOI: 10.1002/jps.2600840902] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
With a few exceptions, dielectric relaxation spectroscopy (DRS) has been largely neglected by pharmaceutical scientists, despite the potential for this technique as a noninvasive and rapid method for the structural characterization and quality control of pharmaceutical materials. DRS determines both the magnitude and time dependency of electrical polarization (i.e. the separation of localized charge distributions) by either measuring the ability of the material to pass alternating current (frequency domain DRS) or by investigating the current that flows on application of a step voltage (time domain DRS). DRS is thus (i) sensitive to molecular mobility and structure, (ii) non-invasive, and (iii) employs only mild stresses (a weak electromagnetic field) in order to measure the sample properties. The technique covers a broad-band frequency window (from 10(-5) to 10(11) Hz) and therefore enables the investigation of a diverse range of processes, from slow and hindered macromolecular vibrations and restricted charge transfer processes (such as proton conductivity in nearly dry systems) to the relatively fast reorientations of small molecules or side chain groups. The dielectric response provides information on (i) structural characteristics of polymers, gels, proteins, and emulsions, (ii) the interfacial properties of molecular films, (iii) membrane properties, (iv) water content and states of water (and the effects of water as a plasticizer), and (v) lyophilization of biomolecules. This review article details the basis of dielectric theory and the principles of measuring dielectric properties (including a comprehensive account of measurement artifacts), and gives some applications of DRS to the pharmaceutical sciences.
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Affiliation(s)
- G Smith
- Department of Pharmaceutical Sciences, De Montfort University, Leicester, UK
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38
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Duddu SP, Sokoloski TD. Dielectric analysis in the characterization of amorphous pharmaceutical solids. 1. Molecular mobility in poly(vinylpyrrolidone)-water systems in the glassy state. J Pharm Sci 1995; 84:773-6. [PMID: 7562421 DOI: 10.1002/jps.2600840621] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effect of water on the relaxation behavior below the glass transition temperature (beta-relaxation) of an amorphous powder, poly(vinylpyrrolidone) (PVP, MW 30,000), was studied by subjecting the sample to dielectric analysis in the frequency range from 20 Hz to 20 kHz. The material stored at 0% relative humidity (RH) (containing 0.05% w/w H2O) exhibited a frequency dependent second-order beta-relaxation (T beta = -56 degrees C at 500 Hz). The peak frequency-temperature data could be fitted to the Arrhenius equation, yielding an activation energy (Ea) of 36.5 kJ mol-1. Water was found to significantly lower T beta, increase the dielectric loss, and increase Ea. The initial decrease in T beta was found to be quite significant, as little as 7% w/w H2O lowering T beta by 26 degrees C, followed by a more gradual decrease. PVP exposed to 69% RH (containing approximately 31% w/w H2O) exhibited T beta at -104 degrees C with an activation energy of 46.3 kJ mol-1. The observations that the beta relaxation was poorly visible when the water content was 0.05% w/w and that the change in Ea was from a low to a high value as the temperature is decreased suggest that thermally activated rotational diffusion of water molecules plays a major role in the beta-relaxation of PVP containing moderate to high water contents. The rate of increase in activation energy as a function of H2O/PVP mole ratio exhibited a minimum at unity, suggesting that water binding to one site on PVP has a distinct effect on the activation energy.
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Affiliation(s)
- S P Duddu
- Department of Pharmaceutical Technologies, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406-0939, USA
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39
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Steinhoff HJ, Kramm B, Hess G, Owerdieck C, Redhardt A. Rotational and translational water diffusion in the hemoglobin hydration shell: dielectric and proton nuclear relaxation measurements. Biophys J 1993; 65:1486-95. [PMID: 8274642 PMCID: PMC1225875 DOI: 10.1016/s0006-3495(93)81217-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The dynamic properties of water in the hydration shell of hemoglobin have been studied by means of dielectric permittivity measurements and nuclear magnetic resonance spectroscopy. The temperature behavior of the complex permittivity of hemoglobin solutions has been measured at 3.02, 3.98, 8.59, and 10.80 GHz. At a temperature of 298 K the average rotational correlation time tau of water within a hydration shell of 0.5-nm thickness is determined from the activation parameters to be 68 +/- 10 ps, which is 8-fold the corresponding value of bulk water. Solvent proton magnetic relaxation induced by electron-nuclear dipole interaction between hemoglobin bound nitroxide spin labels and water protons is used to determine the translational diffusion coefficient D(T) of the hydration water. The temperature dependent relaxation behavior for Lamor frequencies between 3 and 90 MHz yields an average value D(298K) = (5 +/- 2) x 10(-10)m2 s-1, which is about one-fifth of the corresponding value of bulk water. The decrease of the water mobility in the hydration shell compared to the bulk is mainly due to an enhanced activation enthalpy.
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Affiliation(s)
- H J Steinhoff
- Institut für Biophysik, Ruhr-Universität Bochum, Germany
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40
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41
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Mattey M, Naftalin L. Mechanoelectrical transduction, ion movement and water stasis in uromodulin. EXPERIENTIA 1992; 48:975-80. [PMID: 1426148 DOI: 10.1007/bf01919145] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Mechanical movement of a column of the urinary glycoprotein uromodulin modulates an applied voltage. This change is a property of the glycoprotein and its interaction with the walls of the container and is related to its capacitance. The voltage modulation is not accompanied by changes in rotationally restricted water as has been reported for hyaluronic acid. Diffusion experiments with tritiated water also support the hypothesis that uromodulin acts as a water barrier, but allows ion movement.
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Affiliation(s)
- M Mattey
- Department of Bioscience and Biotechnology, University of Strathclyde, Glasgow, Scotland
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Pissis P, Daoukaki-Daimanti D. Dielectric relaxation of water in the water-methylcellulose system. Chem Phys 1988. [DOI: 10.1016/0301-0104(88)87042-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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44
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Pethig R, Kell DB. The passive electrical properties of biological systems: their significance in physiology, biophysics and biotechnology. Phys Med Biol 1987; 32:933-70. [PMID: 3306721 DOI: 10.1088/0031-9155/32/8/001] [Citation(s) in RCA: 612] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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