1
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Kamp D. A physical perspective on lithium therapy. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2024; 194:55-74. [PMID: 39547449 DOI: 10.1016/j.pbiomolbio.2024.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2024] [Revised: 10/31/2024] [Accepted: 11/03/2024] [Indexed: 11/17/2024]
Abstract
Lithium salts have strong medical properties in neurological disorders such as bipolar disorder and lithium-responsive headaches. They have recently gathered attention due to their potential preventive effect in viral infections. Though the therapeutic effect of lithium was documented by Cade in the late 1940s, its underlying mechanism of action is still disputed. Acute lithium exposure has an activating effect on excitable organic tissue and organisms, and is highly toxic. Lithium exposure is associated with a strong metabolic response in the organism, with large changes in phospholipid and cholesterol expression. Opposite to acute exposure, this metabolic response alleviates excessive cellular activity. The presence of lithium ions strongly affects lipid conformation and membrane phase unlike other alkali ions, with consequences for membrane permeability, buffer property and excitability. This review investigates how lithium ions affect lipid membrane composition and function, and how lithium response might in fact be the body's attempt to counteract the physical presence of lithium ions at cell level. Ideas for further research in microbiology and drug development are discussed.
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Affiliation(s)
- Dana Kamp
- The Niels Bohr Institute, Copenhagen University, Copenhagen, Denmark.
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2
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Heimburg T. The mechanical properties of nerves, the size of the action potential, and consequences for the brain. Chem Phys Lipids 2024; 267:105461. [PMID: 39622430 DOI: 10.1016/j.chemphyslip.2024.105461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2024] [Revised: 11/22/2024] [Accepted: 11/27/2024] [Indexed: 12/12/2024]
Abstract
The action potential is widely regarded as a purely electrical phenomenon. However, one also finds mechanical and thermal changes that can be observed experimentally. In particular, nerve membranes become thicker and axons contract. The spatial length of the action potential can be quite large, ranging from millimeters to many centimeters. This suggests the use of macroscopic thermodynamics methods to understand its properties. The pulse length is several orders of magnitude larger than the synaptic gap, larger than the distance of the nodes of Ranvier and even larger than the size of many neurons such as pyramidal cells or brain stem motor neurons. Here, we review the mechanical changes in nerves, we discuss theoretical possibilities to explain them and implications of a mechanical nerve pulse for neurons and for the brain. In particular, the contraction of nerves leads to the possibility of fast mechanical synapses.
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Affiliation(s)
- Thomas Heimburg
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark.
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3
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Heimburg T. The thermodynamic soliton theory of the nervous impulse and possible medical implications. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 173:24-35. [PMID: 35640761 DOI: 10.1016/j.pbiomolbio.2022.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/05/2022] [Accepted: 05/22/2022] [Indexed: 06/15/2023]
Abstract
The textbook picture of nerve activity is that of a propagating voltage pulse driven by electrical currents through ion channel proteins, which are gated by changes in voltage, temperature, pressure or by drugs. All function is directly attributed to single molecules. We show that this leaves out many important thermodynamic couplings between different variables. A more recent alternative picture for the nerve pulse is of thermodynamic nature. It considers the nerve pulse as a soliton, i.e., a macroscopic excited region with properties that are influenced by thermodynamic variables including voltage, temperature, pressure and chemical potentials of membrane components. All thermodynamic variables are strictly coupled. We discuss the consequences for medical treatment in a view where one can compensate a maladjustment of one variable by adjusting another variable. For instance, one can explain why anesthesia can be counteracted by hydrostatic pressure and decrease in pH, suggest reasons why lithium over-dose may lead to tremor, and how tremor is related to alcohol intoxication. Lithium action as well as the effect of ethanol and the anesthetic ketamine in bipolar patients may fall in similar thermodynamic patterns. Such couplings remain obscure in a purely molecular picture. Other fields of application are the response of nerve activity to muscle stretching and the possibility of neural stimulation by ultrasound.
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Affiliation(s)
- T Heimburg
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen Ø, Denmark.
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4
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Dey S, Surendran D, Engberg O, Gupta A, Fanibunda SE, Das A, Maity BK, Dey A, Visvakarma V, Kallianpur M, Scheidt HA, Walker G, Vaidya VA, Huster D, Maiti S. Altered Membrane Mechanics Provides a Receptor-Independent Pathway for Serotonin Action. Chemistry 2021; 27:7533-7541. [PMID: 33502812 PMCID: PMC8252079 DOI: 10.1002/chem.202100328] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Indexed: 12/20/2022]
Abstract
Serotonin, an important signaling molecule in humans, has an unexpectedly high lipid membrane affinity. The significance of this finding has evoked considerable speculation. Here we show that membrane binding by serotonin can directly modulate membrane properties and cellular function, providing an activity pathway completely independent of serotonin receptors. Atomic force microscopy shows that serotonin makes artificial lipid bilayers softer, and induces nucleation of liquid disordered domains inside the raft-like liquid-ordered domains. Solid-state NMR spectroscopy corroborates this data at the atomic level, revealing a homogeneous decrease in the order parameter of the lipid chains in the presence of serotonin. In the RN46A immortalized serotonergic neuronal cell line, extracellular serotonin enhances transferrin receptor endocytosis, even in the presence of broad-spectrum serotonin receptor and transporter inhibitors. Similarly, it increases the membrane binding and internalization of oligomeric peptides. Our results uncover a mode of serotonin-membrane interaction that can potentiate key cellular processes in a receptor-independent fashion.
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Affiliation(s)
- Simli Dey
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Dayana Surendran
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Oskar Engberg
- Institute of Medical Physics and BiophysicsUniversity of LeipzigHärtelstr. 16–1804107LeipzigGermany
| | - Ankur Gupta
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Sashaina E. Fanibunda
- Department of Biological SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
- Kasturba Health SocietyMedical Research CenterMumbaiIndia
| | - Anirban Das
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Barun Kumar Maity
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Arpan Dey
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Vicky Visvakarma
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Mamata Kallianpur
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Holger A. Scheidt
- Institute of Medical Physics and BiophysicsUniversity of LeipzigHärtelstr. 16–1804107LeipzigGermany
| | - Gilbert Walker
- Department of ChemistryUniversity of TorontoTorontoOntarioM5S3H6Canada
| | - Vidita A. Vaidya
- Department of Biological SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
| | - Daniel Huster
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
- Institute of Medical Physics and BiophysicsUniversity of LeipzigHärtelstr. 16–1804107LeipzigGermany
| | - Sudipta Maiti
- Department of Chemical SciencesTata Institute of Fundamental ResearchHomi Bhabha Road, ColabaMumbai400005India
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5
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Zecchi KA, Heimburg T. Non-linear Conductance, Rectification, and Mechanosensitive Channel Formation of Lipid Membranes. Front Cell Dev Biol 2021; 8:592520. [PMID: 33575253 PMCID: PMC7870788 DOI: 10.3389/fcell.2020.592520] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/10/2020] [Indexed: 01/04/2023] Open
Abstract
There is mounting evidence that lipid bilayers display conductive properties. However, when interpreting the electrical response of biological membranes to voltage changes, they are commonly considered as inert insulators. Lipid bilayers under voltage-clamp conditions display current traces with discrete conduction-steps, which are indistinguishable from those attributed to the presence of protein channels. In current-voltage (I-V) plots they may also display outward rectification, i.e., voltage-gating. Surprisingly, this has even been observed in chemically symmetric lipid bilayers. Here, we investigate this phenomenon using a theoretical framework that models the electrostrictive effect of voltage on lipid membranes in the presence of a spontaneous polarization, which can be recognized by a voltage offset in electrical measurements. It can arise from an asymmetry of the membrane, for example from a non-zero spontaneous curvature of the membrane. This curvature can be caused by voltage via the flexoelectric effect, or by hydrostatic pressure differences across the membrane. Here, we describe I-V relations for lipid membranes formed at the tip of patch pipettes situated close to an aqueous surface. We measured at different depths relative to air/water surface, resulting in different pressure gradients across the membrane. Both linear and non-linear I-V profiles were observed. Non-linear conduction consistently takes the form of outward rectified currents. We explain the conductance properties by two mechanisms: One leak current with constant conductance without pores, and a second process that is due to voltage-gated pore opening correlating with the appearance of channel-like conduction steps. In some instances, these non-linear I-V relations display a voltage regime in which dI/dV is negative. This has also been previously observed in the presence of sodium channels. Experiments at different depths reveal channel formation that depends on pressure gradients. Therefore, we find that the channels in the lipid membrane are both voltage-gated and mechanosensitive. We also report measurements on black lipid membranes that also display rectification. In contrast to the patch experiments they are always symmetric and do not display a voltage offset.
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Affiliation(s)
- Karis Amata Zecchi
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Heimburg
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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6
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Bochicchio A, Brandner AF, Engberg O, Huster D, Böckmann RA. Spontaneous Membrane Nanodomain Formation in the Absence or Presence of the Neurotransmitter Serotonin. Front Cell Dev Biol 2020; 8:601145. [PMID: 33330494 PMCID: PMC7734319 DOI: 10.3389/fcell.2020.601145] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/06/2020] [Indexed: 11/23/2022] Open
Abstract
Detailed knowledge on the formation of biomembrane domains, their structure, composition, and physical characteristics is scarce. Despite its frequently discussed importance in signaling, e.g., in obtaining localized non-homogeneous receptor compositions in the plasma membrane, the nanometer size as well as the dynamic and transient nature of domains impede their experimental characterization. In turn, atomistic molecular dynamics (MD) simulations combine both, high spatial and high temporal resolution. Here, using microsecond atomistic MD simulations, we characterize the spontaneous and unbiased formation of nano-domains in a plasma membrane model containing phosphatidylcholine (POPC), palmitoyl-sphingomyelin (PSM), and cholesterol (Chol) in the presence or absence of the neurotransmitter serotonin at different temperatures. In the ternary mixture, highly ordered and highly disordered domains of similar composition coexist at 303 K. The distinction of domains by lipid acyl chain order gets lost at lower temperatures of 298 and 294 K, suggesting a phase transition at ambient temperature. By comparison of domain ordering and composition, we demonstrate how the domain-specific binding of the neurotransmitter serotonin results in a modified domain lipid composition and a substantial downward shift of the phase transition temperature. Our simulations thus suggest a novel mode of action of neurotransmitters possibly of importance in neuronal signal transmission.
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Affiliation(s)
- Anna Bochicchio
- Computational Biology, Department Biology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Astrid F Brandner
- Computational Biology, Department Biology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Oskar Engberg
- Institute for Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany
| | - Daniel Huster
- Institute for Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany.,Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Rainer A Böckmann
- Computational Biology, Department Biology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
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7
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Heimburg T. The important consequences of the reversible heat production in nerves and the adiabaticity of the action potential. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 162:26-40. [PMID: 32805276 DOI: 10.1016/j.pbiomolbio.2020.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 05/30/2020] [Accepted: 07/23/2020] [Indexed: 02/05/2023]
Abstract
It has long been known that there is no measurable heat production associated with the nerve pulse. Rather, one finds that heat production is biphasic, and a heat release during the first phase of the action potential is followed by the reabsorption of a similar amount of heat during the second phase. We review the long history the measurement of heat production in nerves and provide a new analysis of these findings focusing on the thermodynamics of adiabatic and isentropic processes. We begin by considering adiabatic oscillations in gases, waves in layers, oscillations of springs and the reversible (or irreversible) charging and discharging of capacitors. We then apply these ideas to the heat signature of nerve pulses. Finally, we compare the temperature changes expected from the Hodgkin-Huxley model and the soliton theory for nerves. We demonstrate that heat production in nerves cannot be explained as an irreversible charging and discharging of a membrane capacitor as it is proposed in the Hodgkin-Huxley model. Instead, we conclude that it is consistent with an adiabatic pulse. However, if the nerve pulse is adiabatic, completely different physics is required to explain its features. Membrane processes must then be reversible and resemble the oscillation of springs more than resembling "a burning fuse of gunpowder" (quote A. L. Hodgkin). Theories acknowledging the adiabatic nature of the nerve pulse have recently been discussed by various authors. It forms the central core of the soliton model, which considers the nerve pulse as a localized sound pulse.
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Affiliation(s)
- Thomas Heimburg
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen Ø, Denmark.
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8
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Kang KH, Schneider MF. Nonlinear pulses at the interface and its relation to state and temperature. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2020; 43:8. [PMID: 32016590 DOI: 10.1140/epje/i2020-11903-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
Environmental temperature has a well-conserved effect on the pulse velocity and excitability of excitable biological systems. The consistency suggests that the cause originates from a fundamental principle. A physical (hydrodynamic) approach has proposed that the thermodynamic state of the hydrated interface (e.g., plasma membrane) determines the pulse behavior. This implies that the temperature effect happens because the environmental temperature affects the state of the interface in any given system. To test the hypothesis, we measured temperature-dependent phase diagrams of a lipid monolayer and studied the properties of nonlinear acoustic pulses excited along the membrane. We observed that the membrane in the fluid-gel transition regime exhibited lower compressibility (i.e., stiffer) overall with increasing temperature. Nonlinear pulses excited near the transition state propagated with greater velocity with increasing temperature, and these observations were consistent with the compressibility profiles. Excitability was suppressed significantly or ceased completely when the state departed too far from the transition regime either by cooling or by heating. The overall correlation between the pulses in the membrane and in living systems as a function of temperature supports the view that the thermodynamic state of the interface and phase transition are the key to understanding pulse propagation in excitable systems.
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Affiliation(s)
- Kevin H Kang
- Department of Physics, Technical University of Dortmund, Dortmund, Germany
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9
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Mužić T, Tounsi F, Madsen SB, Pollakowski D, Konrad M, Heimburg T. Melting transitions in biomembranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:183026. [PMID: 31465764 DOI: 10.1016/j.bbamem.2019.07.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/15/2019] [Accepted: 07/17/2019] [Indexed: 12/26/2022]
Abstract
We investigated melting transitions in native biological membranes containing their membrane proteins. The membranes originated from E. coli, B. subtilis, lung surfactant and nerve tissue from the spinal cord of several mammals. For some preparations, we studied the pressure, pH and ionic strength dependence of the transition. For porcine spine, we compared the transition of the native membrane to that of the extracted lipids. All preparations displayed melting transitions of 10-20° below physiological or growth temperature, independent of the organism of origin and the respective cell type. We found that the position of the transitions in E. coli membranes depends on the growth temperature. We discuss these findings in the context of the thermodynamic theory of membrane fluctuations close to transition that predicts largely altered elastic constants, an increase in fluctuation lifetime and in membrane permeability. We also discuss how to distinguish lipid melting from protein unfolding transitions. Since the feature of a transition slightly below physiological temperature is conserved even when growth conditions change, we conclude that the transitions are likely to be of major biological importance for the survival and the function of the cell.
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Affiliation(s)
- Tea Mužić
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark
| | - Fatma Tounsi
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark
| | - Søren B Madsen
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark
| | - Denis Pollakowski
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark
| | - Manfred Konrad
- Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany
| | - Thomas Heimburg
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark.
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10
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 195] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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11
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12
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Lebecque S, Crowet JM, Lins L, Delory BM, du Jardin P, Fauconnier ML, Deleu M. Interaction between the barley allelochemical compounds gramine and hordenine and artificial lipid bilayers mimicking the plant plasma membrane. Sci Rep 2018; 8:9784. [PMID: 29955111 PMCID: PMC6023908 DOI: 10.1038/s41598-018-28040-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 06/04/2018] [Indexed: 11/09/2022] Open
Abstract
Some plants affect the development of neighbouring plants by releasing secondary metabolites into their environment. This phenomenon is known as allelopathy and is a potential tool for weed management within the framework of sustainable agriculture. While many studies have investigated the mode of action of various allelochemicals (molecules emitted by allelopathic plants), little attention has been paid to their initial contact with the plant plasma membrane (PPM). In this paper, this key step is explored for two alkaloids, gramine and hordenine, that are allelochemicals from barley. Using in vitro bioassays, we first showed that gramine has a greater toxicity than hordenine towards a weed commonly found in northern countries (Matricaria recutita L.). Then, isothermal titration calorimetry was used to show that these alkaloids spontaneously interact with lipid bilayers that mimic the PPM. The greater impact of gramine on the thermotropic behaviour of lipids compared to hordenine was established by means of infrared spectroscopy. Finally, the molecular mechanisms of these interactions were explored with molecular dynamics simulations. The good correlation between phytotoxicity and the ability to disturb lipid bilayers is discussed. In this study, biophysical tools were used for the first time to investigate the interactions of allelochemicals with artificial PPM.
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Affiliation(s)
- Simon Lebecque
- TERRA-AgricultureIsLife, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
- Laboratory of Molecular Biophysics at Interfaces, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Jean-Marc Crowet
- Laboratory of Molecular Biophysics at Interfaces, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Laurence Lins
- Laboratory of Molecular Biophysics at Interfaces, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Benjamin M Delory
- Ecosystem Functioning and Services, Institute of Ecology, Leuphana University, Universitätsallee 1, 21335, Lüneburg, Germany
| | - Patrick du Jardin
- Laboratory of Plant Biology, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Marie-Laure Fauconnier
- General and Organic Chemistry Laboratory, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium.
| | - Magali Deleu
- Laboratory of Molecular Biophysics at Interfaces, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium.
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13
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Peters J, Marion J, Becher FJ, Trapp M, Gutberlet T, Bicout DJ, Heimburg T. Thermodynamics of lipid multi-lamellar vesicles in presence of sterols at high hydrostatic pressure. Sci Rep 2017; 7:15339. [PMID: 29127413 PMCID: PMC5681575 DOI: 10.1038/s41598-017-15582-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 10/30/2017] [Indexed: 01/28/2023] Open
Abstract
We compared the effect of cholesterol at different concentration on the phase behaviour of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) multilamellar vesicles. We used pressure perturbation differential scanning calorimetry (PPC) that studies a system on the whole by giving access to relevant thermodynamic quantities, and elastic incoherent neutron scattering (EINS) that probes local motions of a system at the atomic level by allowing extraction of dynamical parameters. PPC revealed that the volume expansion coefficient of DMPC and DMPC/Cholesterol samples with 13 and 25 mol% cholesterol is a linear function of the heat capacity measured by differential scanning calorimetry. Neutron backscattering spectroscopy showed that the mean square displacements of H atoms do exhibit an increase with temperature and a decrease under increasing pressure. Cholesterol added at concentrations of 25 and 50 mol% led to suppression of the main phase transition. Taking advantage of these results, the present study aims (i) to show that calorimetry and EINS using the Bicout and Zaccai model equally permit to get access to thermodynamic quantities characterizing pure DMPC and DMPC/cholesterol mixtures, thus directly confirming the theoretical method, and (ii) to validate our approach as function of temperature and of pressure, as both are equally important and complementary thermodynamic variables.
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Affiliation(s)
- J Peters
- Univ. Grenoble Alpes, LiPhy, 140 Rue de la Physique, 38402, Saint-Martin-d'Hères, France. .,Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042, Grenoble cedex 9, France.
| | - J Marion
- Univ. Grenoble Alpes, LiPhy, 140 Rue de la Physique, 38402, Saint-Martin-d'Hères, France.,Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042, Grenoble cedex 9, France
| | - F J Becher
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen, Denmark.,Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, UK
| | - M Trapp
- Helmholtz-Zentrum Berlin für Materialien und Energie, Lise-Meitner Campus, Hahn-Meitner-Platz 1, 14109, Berlin, Germany
| | - T Gutberlet
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748, Garching, Germany
| | - D J Bicout
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042, Grenoble cedex 9, France.,Biomathématiques et épidémiologie, EPSP - TIMC-IMAG, UMR CNRS 5525, Université Grenoble Alpes, VetAgro Sup Lyon, 69280, Marcy l'Etoile, France
| | - T Heimburg
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen, Denmark
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14
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Potekhin SA, Khusainova RS. Dependence on acyl chain length of energy and volume parameters of the gel to liquid-crystalline transition of 1,2-diacylphosphatidylcholines. Theoretical consideration. Biophys Chem 2017; 227:29-33. [PMID: 28578831 DOI: 10.1016/j.bpc.2017.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/03/2017] [Accepted: 05/17/2017] [Indexed: 11/29/2022]
Abstract
The effect of acyl chain length on energy and volume parameters of gel to liquid-crystal transitions in phospholipids is analyzed. It is demonstrated that simple structural and thermodynamic considerations allow predicting some thermodynamic and volume characteristics of transitions and their dependencies on the acyl chains length.
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Affiliation(s)
- Sergey A Potekhin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia.
| | - Railya S Khusainova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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15
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Peschel A, Langhoff A, Uhl E, Dathathreyan A, Haindl S, Johannsmann D, Reviakine I. Lipid phase behavior studied with a quartz crystal microbalance: A technique for biophysical studies with applications in screening. J Chem Phys 2017; 145:204904. [PMID: 27908120 DOI: 10.1063/1.4968215] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Quartz crystal microbalance (QCM) is emerging as a versatile tool for studying lipid phase behavior. The technique is attractive for fundamental biophysical studies as well applications because of its simplicity, flexibility, and ability to work with very small amounts of material crucial for biomedical studies. Further progress hinges on the understanding of the mechanism, by which a surface-acoustic technique such as QCM, senses lipid phase changes. Here, we use a custom-built instrument with improved sensitivity to investigate phase behavior in solid-supported lipid systems of different geometries (adsorbed liposomes and bilayers). We show that we can detect a model anesthetic (ethanol) through its effect on the lipid phase behavior. Further, through the analysis of the overtone dependence of the phase transition parameters, we show that hydrodynamic effects are important in the case of adsorbed liposomes, and viscoelasticity is significant in supported bilayers, while layer thickness changes make up the strongest contribution in both systems.
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Affiliation(s)
- Astrid Peschel
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Eva Uhl
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Aruna Dathathreyan
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Susanne Haindl
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Ilya Reviakine
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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16
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Shafique N, Kennedy KE, Douglas JF, Starr FW. Quantifying the Heterogeneous Dynamics of a Simulated Dipalmitoylphosphatidylcholine (DPPC) Membrane. J Phys Chem B 2016; 120:5172-82. [DOI: 10.1021/acs.jpcb.6b02982] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Jack F. Douglas
- Materials
Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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17
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Velikonja A, Kramar P, Miklavčič D, Maček Lebar A. Specific electrical capacitance and voltage breakdown as a function of temperature for different planar lipid bilayers. Bioelectrochemistry 2016; 112:132-7. [PMID: 26948707 DOI: 10.1016/j.bioelechem.2016.02.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 02/15/2016] [Accepted: 02/23/2016] [Indexed: 12/16/2022]
Abstract
The breakdown voltage and specific electrical capacitance of planar lipid bilayers formed from lipids isolated from the membrane of archaeon Aeropyrum pernix K1 as a function of temperature were studied and compared with data obtained previously in MD simulation studies. Temperature dependence of breakdown voltage and specific electrical capacitance was measured also for dipalmitoylphosphatidylcholine (DPPC) bilayers and bilayers formed from mixture of diphytanoylphosphocholine (DPhPC) and DPPC in ratio 80:20. The breakdown voltage of archaeal lipids planar lipid bilayers is more or less constant until 50°C, while at higher temperatures a considerable drop is observed, which is in line with the results from MD simulations. The breakdown voltage of DPPC planar lipid bilayer at melting temperature is considerably higher than in the gel phase. Specific electrical capacitance of planar lipid bilayers formed from archaeal lipids is approximately constant for temperatures up to 40°C and then gradually decreases. The difference with MD simulation predictions is discussed. Specific electrical capacitance of DPPC planar lipid bilayers in fluid phase is 1.75 times larger than that of the gel phase and it follows intermediated phases before phase transition. Increase in specific electrical capacitance while approaching melting point of DPPC is visible also for DPhPC:DPPC mixture.
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Affiliation(s)
- Aljaž Velikonja
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
| | - Peter Kramar
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
| | - Damijan Miklavčič
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
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18
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Mosgaard LD, Zecchi KA, Heimburg T, Budvytyte R. The Effect of the Nonlinearity of the Response of Lipid Membranes to Voltage Perturbations on the Interpretation of Their Electrical Properties. A New Theoretical Description. MEMBRANES 2015; 5:495-512. [PMID: 26426061 PMCID: PMC4703996 DOI: 10.3390/membranes5040495] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 09/22/2015] [Indexed: 11/18/2022]
Abstract
Our understanding of the electrical properties of cell membranes is derived from experiments where the membrane is exposed to a perturbation (in the form of a time-dependent voltage or current change) and information is extracted from the measured output. The interpretation of such electrical recordings consists in finding an electronic equivalent that would show the same or similar response as the biological system. In general, however, there is no unique circuit configuration, which can explain a single electrical recording and the choice of an electric model for a biological system is based on complementary information (most commonly structural information) of the system investigated. Most of the electrophysiological data on cell membranes address the functional role of protein channels while assuming that the lipid matrix is an insulator with constant capacitance. However, close to their melting transition the lipid bilayers are no inert insulators. Their conductivity and their capacitance are nonlinear functions of both voltage, area and volume density. This has to be considered when interpreting electrical data. Here we show how electric data commonly interpreted as gating currents of proteins and inductance can be explained by the nonlinear dynamics of the lipid matrix itself.
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Affiliation(s)
- Lars D Mosgaard
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark.
| | - Karis A Zecchi
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark.
| | - Thomas Heimburg
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark.
| | - Rima Budvytyte
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark.
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19
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Berndt N, Holzhütter HG. The high energy demand of neuronal cells caused by passive leak currents is not a waste of energy. Cell Biochem Biophys 2014; 67:527-35. [PMID: 23479331 DOI: 10.1007/s12013-013-9538-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
It is estimated that maintenance of the resting potential of neurons consumes between 15% (in gray matter) and 44% (in fully myelinated white matter) of the brain's total energy budget [1]. This poses the intriguing question why evolution has not strived to lower the permeability of passive ion channels to cut the high resting-state energy budget of the brain. Based on a conceptual mathematical model of neuronal ion currents and action potential (AP) firing we demonstrate that a neuron endowed with small leak currents and correspondingly low energy consumption by the Na(+)/K(+)-ATPase in the resting state may indeed recapitulate all features of normal AP firing. However, the activation and inactivation of such a "low-energy-cost neuron" turns out to be extremely sensitive to small fluctuation of Na(+) currents associated with Na(+)-dependent secondary-active transport that is indispensable for the metabolic integrity of the cell and neurotransmitter recycling. We provide evidence that sufficiently large leak currents function as important stabilizers of the membrane potential and thus are required to allow robust AP firing. Our simulations suggest that the energy demand of the Na(+)/K(+)-ATPase needed to counterbalance passive leak currents cannot be significantly dropped below observed values.
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Affiliation(s)
- Nikolaus Berndt
- Computational Biochemistry Group, Institute of Biochemistry, University Medicine Berlin (Charité), Charitéplatz 1/Sitz: Virchowweg 6, 10117, Berlin, Germany,
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20
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Starr FW, Hartmann B, Douglas JF. Dynamical clustering and a mechanism for raft-like structures in a model lipid membrane. SOFT MATTER 2014; 10:3036-47. [PMID: 24695573 PMCID: PMC4020150 DOI: 10.1039/c3sm53187b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We use molecular dynamics simulations to examine the dynamical heterogeneity of a model single-component lipid membrane using a coarse-grained representation of lipid molecules. This model qualitatively reproduces the known phase transitions between disordered, ordered, and gel membrane phases, and the phase transitions are accompanied by significant changes in the nature of the lipid dynamics. In particular, lipid diffusion in the liquid-ordered phase is hindered by the transient trapping of molecules by their neighbors, similar to the dynamics of a liquid approaching its glass transition. This transient molecular caging gives rise to two distinct mobility groups within a single-component membrane: lipids that are transiently trapped, and lipids with displacements on the scale of the intermolecular spacing. Most significantly, lipids within these distinct mobility states spatially segregate, creating transient "islands" of enhanced mobility having a size and time scale compatible with lipid "rafts," dynamical structures thought to be important for cell membrane function. Although the dynamic lipid clusters that we observe do not themselves correspond to rafts (which are more complex, multicomponent structures), we hypothesize that such rafts may develop from the same universal mechanism, explaining why raft-like regions should arise, regardless of lipid structural or compositional details. These clusters are strikingly similar to the dynamical clusters found in glass-forming fluids, and distinct from phase-separation clusters. We also show that mobile lipid clusters can be dissected into smaller clusters of cooperatively rearranging molecules. The geometry of these clusters can be understood in the context of branched equilibrium polymers, related to percolation theory. We discuss how these dynamical structures relate to a range observations on the dynamics of lipid membranes.
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Affiliation(s)
- Francis W Starr
- Department of Physics, Wesleyan University, Middletown, CT 06459, USA.
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21
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Kopec W, Khandelia H. Reinforcing the membrane-mediated mechanism of action of the anti-tuberculosis candidate drug thioridazine with molecular simulations. J Comput Aided Mol Des 2014; 28:123-34. [DOI: 10.1007/s10822-014-9737-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/19/2014] [Indexed: 10/25/2022]
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22
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Mosgaard LD, Jackson AD, Heimburg T. Fluctuations of systems in finite heat reservoirs with applications to phase transitions in lipid membranes. J Chem Phys 2013; 139:125101. [DOI: 10.1063/1.4821837] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Jodko-Piorecka K, Litwinienko G. First experimental evidence of dopamine interactions with negatively charged model biomembranes. ACS Chem Neurosci 2013; 4:1114-22. [PMID: 23662798 DOI: 10.1021/cn4000633] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dopamine is essential for receptor-related signal transduction in mammalian central and peripheral nervous systems. Weak interactions between the neurotransmitter and neuronal membranes have been suggested to modulate synaptic transmission; however, binding forces between dopamine and neuronal membranes have not yet been quantitatively described. Herein, for the first time, we have explained the nature of dopamine interactions with model lipid membranes assembled from neutral 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), negatively charged 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG), and the mixture of these two lipids using isothermal titration calorimetry and differential scanning calorimetry. Dopamine binding to anionic membranes is a thermodynamically favored process with negative enthalpy and positive entropy, quantitatively described by the mole ratio partition coefficient, K. K increases with membrane charge to reach its maximal value, 705.4 ± 60.4 M(-1), for membrane composed from pure DMPG. The contribution of hydrophobic effects to the binding process is expressed by the intrinsic partition coefficient, K(0). The value of K(0) = 74.7 ± 6.4 M(-1) for dopamine/DMPG interactions clearly indicates that hydrophobic effects are 10 times weaker than electrostatic forces in this system. The presence of dopamine decreases the main transition temperature of DMPG, but no similar effect has been observed for DMPC. Basing on these results, we propose a simple electrostatic model of dopamine interactions with anionic membranes with the hydrophobic contribution expressed by K(0). We suggest that dopamine interacts superficially with phospholipid membranes without penetrating into the bilayer hydrocarbon core. The model is physiologically important, since neuronal membranes contain a large (even 20%) fraction of anionic lipids.
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Affiliation(s)
- Katarzyna Jodko-Piorecka
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
- MEMPHYS − Center for
Biomembrane Physics, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230
Odense M, Denmark
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24
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Abstract
Synthetic lipid membranes can display channel-like ion conduction events even in the absence of proteins. We show here that these events are voltage-gated with a quadratic voltage dependence as expected from electrostatic theory of capacitors. To this end, we recorded channel traces and current histograms in patch-experiments on lipid membranes. We derived a theoretical current-voltage relationship for pores in lipid membranes that describes the experimental data very well when assuming an asymmetric membrane. We determined the equilibrium constant between closed and open state and the open probability as a function of voltage. The voltage-dependence of the lipid pores is found comparable to that of protein channels. Lifetime distributions of open and closed events indicate that the channel open distribution does not follow exponential statistics but rather power law behavior for long open times.
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Affiliation(s)
- Andreas Blicher
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Heimburg
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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25
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Kopeć W, Telenius J, Khandelia H. Molecular dynamics simulations of the interactions of medicinal plant extracts and drugs with lipid bilayer membranes. FEBS J 2013; 280:2785-805. [DOI: 10.1111/febs.12286] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 04/10/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Wojciech Kopeć
- MEMPHYS - Center for Biomembrane Physics; University of Southern Denmark; Odense; Denmark
| | - Jelena Telenius
- MEMPHYS - Center for Biomembrane Physics; University of Southern Denmark; Odense; Denmark
| | - Himanshu Khandelia
- MEMPHYS - Center for Biomembrane Physics; University of Southern Denmark; Odense; Denmark
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26
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The capacitance and electromechanical coupling of lipid membranes close to transitions: the effect of electrostriction. Biophys J 2013; 103:918-29. [PMID: 23009841 DOI: 10.1016/j.bpj.2012.07.010] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/09/2012] [Accepted: 07/10/2012] [Indexed: 01/24/2023] Open
Abstract
Biomembranes are thin capacitors with the unique feature of displaying phase transitions in a physiologically relevant regime. We investigate the voltage and lateral pressure dependence of their capacitance close to their chain melting transition. Because the gel and the fluid membrane have different area and thickness, the capacitance of the two membrane phases is different. In the presence of external fields, charges exert forces that can influence the state of the membrane, thereby influencing the transition temperature. This phenomenon is called "electrostriction". We show that this effect allows us to introduce a capacitive susceptibility that assumes a maximum in the melting transition with an associated excess charge. As a consequence, voltage regimes exist in which a small change in voltage can lead to a large uptake of charge and a large capacitive current. Furthermore, we consider electromechanical behavior such as pressure-induced changes in capacitance, and the application of such concepts in biology.
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27
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Peters GH, Wang C, Cruys-Bagger N, Velardez GF, Madsen JJ, Westh P. Binding of serotonin to lipid membranes. J Am Chem Soc 2013; 135:2164-71. [PMID: 23311719 DOI: 10.1021/ja306681d] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is a prevalent neurotransmitter throughout the animal kingdom. It exerts its effect through the specific binding to the serotonin receptor, but recent research has suggested that neural transmission may also be affected by its nonspecific interactions with the lipid matrix of the synaptic membrane. However, membrane-5-HT interactions remain controversial and superficially investigated. Fundamental knowledge of this interaction appears vital in discussions of putative roles of 5-HT, and we have addressed this by thermodynamic measurements and molecular dynamics (MD) simulations. 5-HT was found to interact strongly with lipid bilayers (partitioning coefficient ~1200 in mole fraction units), and this is highly unusual for a hydrophilic solute like 5-HT which has a bulk, oil-water partitioning coefficient well below unity. It follows that membrane affinity must rely on specific interactions, and the MD simulations identified the salt-bridge between the primary amine of 5-HT and the lipid phosphate group as the most important interaction. This interaction anchored cationic 5-HT in the membrane interface with the aromatic ring system pointing inward and a prevailing residence between the phosphate and the carbonyl groups of the lipid. The unprotonated form of 5-HT shows the opposite orientation, with the primary amine pointing toward the membrane core. Partitioning of 5-HT was found to decrease lipid chain order. These distinctive interactions of 5-HT and model membranes could be related to nonspecific effects of this neurotransmitter.
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Affiliation(s)
- Günther H Peters
- Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
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28
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Pogodin S, Werner M, Sommer JU, Baulin VA. Nanoparticle-induced permeability of lipid membranes. ACS NANO 2012; 6:10555-10561. [PMID: 23128273 DOI: 10.1021/nn3028858] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Monte Carlo simulations using the bond fluctuation method with explicit solvent reveal the mechanism of enhanced permeability of lipid bilayers induced by the adsorption of nanoparticles with controlled hydrophobicity. Simulation results indicate an adsorption transition of nanoparticles on the bilayer in a certain range of relative degree of hydrophobicity. In this range the nanoparticles can translocate through the bilayer, reversibly destabilizing the structure of the bilayer and inducing enhanced permeability for water and small solutes. This transition is broader for amphiphilic nanoparticles.
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Affiliation(s)
- Sergey Pogodin
- Departament d'Enginyeria Quimica, Universitat Rovira i Virgili, 26 Avenida dels Paisos Catalans, 43007 Tarragona, Spain
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29
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Laub KR, Witschas K, Blicher A, Madsen SB, Lückhoff A, Heimburg T. Comparing ion conductance recordings of synthetic lipid bilayers with cell membranes containing TRP channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:1123-34. [PMID: 22305677 DOI: 10.1016/j.bbamem.2012.01.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 12/23/2011] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
Abstract
In this article we compare electrical conductance events from single channel recordings of three TRP channel proteins (TRPA1, TRPM2 and TRPM8) expressed in human embryonic kidney cells with channel events recorded on synthetic lipid membranes close to melting transitions. Ion channels from the TRP family are involved in a variety of sensory processes including thermo- and mechano-reception. Synthetic lipid membranes close to phase transitions display channel-like events that respond to stimuli related to changes in intensive thermodynamic variables such as pressure and temperature. TRP channel activity is characterized by typical patterns of current events dependent on the type of protein expressed. Synthetic lipid bilayers show a wide spectrum of electrical phenomena that are considered typical for the activity of protein ion channels. We find unitary currents, burst behavior, flickering, multistep-conductances, and spikes behavior in both preparations. Moreover, we report conductances and lifetimes for lipid channels as described for protein channels. Non-linear and asymmetric current-voltage relationships are seen in both systems. Without further knowledge of the recording conditions, no easy decision can be made whether short current traces originate from a channel protein or from a pure lipid membrane.
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Affiliation(s)
- Katrine R Laub
- Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Denmark
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30
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Low-Frequency Sound Propagation in Lipid Membranes. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/b978-0-12-396534-9.00002-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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31
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Shneider MN, Gimatdinov RS, Skorinkin AI, Kovyazina IV, Nikolsky EE. Hydrodynamic flow in a synaptic cleft during exocytosis. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 41:73-8. [PMID: 22042157 DOI: 10.1007/s00249-011-0759-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 09/14/2011] [Accepted: 10/08/2011] [Indexed: 11/25/2022]
Abstract
It is shown that exocytosis in a chemical synapse may be accompanied by "microjet" formation due to the overpressure that exists in the vesicles. This mechanism may take place either at complete fusion of a vesicle with the presynaptic membrane or in the so-called kiss-and-run mode of neurotransmitter release. A simple hydrodynamic model of the viscous incompressible flow arising in the synaptic cleft is suggested. The occurrence of hydrodynamic flow (microjet) leads to more efficient transport of neurotransmitter than in the case of classical diffusive transport.
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Affiliation(s)
- M N Shneider
- Applied Physics Group, MAE Department, Princeton University, Princeton, NJ, USA.
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32
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Potekhin SA, Senin AA, Abdurakhmanov NN, Khusainova RS. Thermodynamic invariants of gel to the liquid-crystal 1,2-diacylphosphatidylcholines transition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1806-10. [DOI: 10.1016/j.bbamem.2011.02.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 02/09/2011] [Accepted: 02/28/2011] [Indexed: 11/30/2022]
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33
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Tatsumi H, Ueda T. Ion transfer voltammetry of tryptamine, serotonin, and tryptophan at the nitrobenzene/water interface. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2011.02.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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34
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Seeger HM, Aldrovandi L, Alessandrini A, Facci P. Changes in single K(+) channel behavior induced by a lipid phase transition. Biophys J 2011; 99:3675-83. [PMID: 21112292 DOI: 10.1016/j.bpj.2010.10.042] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 10/19/2010] [Accepted: 10/22/2010] [Indexed: 12/01/2022] Open
Abstract
We show that the activity of an ion channel is correlated with the phase state of the lipid bilayer hosting the channel. By measuring unitary conductance, dwell times, and open probability of the K(+) channel KcsA as a function of temperature in lipid bilayers composed of POPE and POPG in different relative proportions, we obtain that all those properties show a trend inversion when the bilayer is in the transition region between the liquid-disordered and the solid-ordered phase. These data suggest that the physical properties of the lipid bilayer influence ion channel activity likely via a fine-tuning of its conformations. In a more general interpretative framework, we suggest that other parameters such as pH, ionic strength, and the action of amphiphilic drugs can affect the physical behavior of the lipid bilayer in a fashion similar to temperature changes resulting in functional changes of transmembrane proteins.
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35
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Raudino A, Sarpietro MG, Pannuzzo M. The thermodynamics of simple biomembrane mimetic systems. JOURNAL OF PHARMACY AND BIOALLIED SCIENCES 2011; 3:15-38. [PMID: 21430953 PMCID: PMC3053513 DOI: 10.4103/0975-7406.76462] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 10/09/2010] [Accepted: 12/15/2010] [Indexed: 11/04/2022] Open
Abstract
Insight into the forces governing a system is essential for understanding its behavior and function. Thermodynamic investigations provide a wealth of information that is not, or is hardly, available from other methods. This article reviews thermodynamic approaches and assays to measure collective properties such as heat adsorption / emission and volume variations. These methods can be successfully applied to the study of lipid vesicles (liposomes) and biological membranes. With respect to instrumentation, differential scanning calorimetry, pressure perturbation calorimetry, isothermal titration calorimetry, dilatometry, and acoustic techniques aimed at measuring the isothermal and adiabatic processes, two- and three-dimensional compressibilities are considered. Applications of these techniques to lipid systems include the measurement of different thermodynamic parameters and a detailed characterization of thermotropic, barotropic, and lyotropic phase behavior. The membrane binding and / or partitioning of solutes (proteins, peptides, drugs, surfactants, ions, etc.) can also be quantified and modeled. Many thermodynamic assays are available for studying the effect of proteins and other additives on membranes, characterizing non-ideal mixing, domain formation, bilayer stability, curvature strain, permeability, solubilization, and fusion. Studies of membrane proteins in lipid environments elucidate lipid-protein interactions in membranes. Finally, a plethora of relaxation phenomena toward equilibrium thermodynamic structures can be also investigated. The systems are described in terms of enthalpic and entropic forces, equilibrium constants, heat capacities, partial volume changes, volume and area compressibility, and so on, also shedding light on the stability of the structures and the molecular origin and mechanism of the structural changes.
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Affiliation(s)
- Antonio Raudino
- University of Catania, Department of Chemistry, Viale A. Doria 6-95125, Catania, Italy
| | | | - Martina Pannuzzo
- University of Catania, Department of Chemistry, Viale A. Doria 6-95125, Catania, Italy
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36
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Griffin KL, Cheng CY, Smith EA, Dea PK. Effects of pentanol isomers on the phase behavior of phospholipid bilayer membranes. Biophys Chem 2010; 152:178-83. [PMID: 20970239 DOI: 10.1016/j.bpc.2010.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 09/23/2010] [Accepted: 09/23/2010] [Indexed: 10/19/2022]
Abstract
Differential scanning calorimetry (DSC) was used to analyze the thermotropic phase behavior of dipalmitoylphosphatidylcholine (DPPC) bilayers in the presence of pentanol isomers. The concentration of each pentanol isomer needed to induce the interdigitated phase was determined by the appearance of a biphasic effect in the main transition temperatures, the onset of a hysteresis associated with the main transition from the gel-to-liquid crystalline phase, and the disappearance of the pretransition. Lower threshold concentrations were found to correlate with isomers of greater alkyl chain length while branching of the alkyl chain was found to increase biphasic behavior. The addition of a methyl group to butanol systems drastically decreased threshold concentrations. However, as demonstrated in the DPPC/neopentanol system, branching of the alkyl chain away from the -OH group lowers the threshold concentration while maintaining a biphasic effect.
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Affiliation(s)
- Kathryn L Griffin
- Department of Chemistry, Occidental College, 1600 Campus Road, Los Angeles, CA 90041, USA
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Heimburg T. Lipid ion channels. Biophys Chem 2010; 150:2-22. [DOI: 10.1016/j.bpc.2010.02.018] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 02/27/2010] [Accepted: 02/27/2010] [Indexed: 10/19/2022]
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Parry MJ, Hagen M, Mouritsen OG, Kinnunen PKJ, Alakoskela JMI. Interlamellar coupling of phospholipid bilayers in liposomes: an emergent property of lipid rearrangement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:4909-4915. [PMID: 20180577 DOI: 10.1021/la9034547] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The thermal phase behaviors of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) large unilamellar vesicles (LUVs) and multilamellar vesicles (MLVs) were compared by fluorescence spectroscopy, using PPDPC (1-palmitoyl-2[10-(pyren-1-yl)]decanoyl-sn-glycero-3-phosphocholine) as a reporter, in parallel with differential scanning calorimetry (DSC). A striking difference is seen between MLVs and LUVs in the lateral organizational dynamics of PPDPC, in particular, below the main phase transition temperature T(m), with efficient clustering of PPDPC into fluid microdomains in the L(beta') and P(beta') (ripple) phases of DPPC MLVs. In the P(beta') phase of MLVs, the probe is likely to become enriched in linear line defects, restricting intermolecular collisions to occur in a quasi one-dimensional system. In contrast, fluorescence and DSC data both suggest that the P(beta') phase is not well-defined in LUVs. Fluorescence anisotropy for 1-palmitoyl-2-[3-(diphenylhexatrienyl)propanoyl]-sn-glycero-3-phosphocholine (DPH-PC) revealed similar acyl chain order for both LUVs and MLVs in the L(beta') and P(beta') phases. However, for MLVs with this probe, T(m) determined from anisotropy was elevated by 0.7 degrees, with higher anisotropy evident in the L(alpha) phase compared to LUVs. These differences in the thermal phase behavior of the two types of liposomes are likely to derive from the augmented acyl chain order due to cooperative coupling of the lamellae of DPPC MLVs, thus manifesting in new, emerging material properties in the latter type of bilayer membrane assembly, as reflected in the organizational dynamics of the pyrene-labeled analogue.
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Affiliation(s)
- Mikko J Parry
- Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine, University of Helsinki, Finland
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Smith EA, van Gorkum CM, Dea PK. Properties of phosphatidylcholine in the presence of its monofluorinated analogue. Biophys Chem 2009; 147:20-7. [PMID: 20064684 DOI: 10.1016/j.bpc.2009.12.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 12/15/2009] [Accepted: 12/15/2009] [Indexed: 10/20/2022]
Abstract
In aqueous solution, the monofluorinated phospholipid 1-palmitoyl-2-[16-fluoropalmitoyl]sn-glycero-3-phosphocholine (F-DPPC) interdigitates without the use of inducing agents. To understand the thermal and physical properties of this unique lipid, F-DPPC was combined with the non-fluorinated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-diarachidoyl-sn-glycero-3-phosphocholine (DAPC). Differential scanning calorimetry (DSC) was used to determine the miscibility and thermotropic phase behavior of these binary lipid mixtures. In addition, the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) and a DPH-labeled analogue of DPPC, 2-(3-(diphenylhexatrienyl) propanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (beta-DPH HPC, aka DPH-PC or DPHpPC), were used to detect interdigitation. In F-DPPC, the fluorescence intensity of both probes decreased a similar amount and to a degree that is consistent with an interdigitated system. We also determined that there are two separate effects of increasing the ratio of F-DPPC in the DPPC/F-DPPC system. With low amounts of F-DPPC, there is little evidence that the system is heavily interdigitated. Instead, we hypothesize that the introduction of F-DPPC provides nucleation sites that alter the kinetics, reversibility, and temperature of the main transition (T(m)). At higher mol% of F-DPPC, we propose that interdigitated F-DPPC-rich domains form to create a phase-segregated system. While DPPC/F-DPPC was highly miscible, the DAPC/F-DPPC system was significantly less miscible. Additionally, we observed that DAPC/F-DPPC samples have reduced solubility in water, which affected the acquisition of fluorescence data. However, our DSC results indicate the existence of DAPC-rich and F-DPPC-rich components. Furthermore, this data support that the mixing was disruptive to lipid packing and that the presence of DAPC hinders the interdigitation of F-DPPC.
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Affiliation(s)
- Eric A Smith
- Department of Chemistry, Occidental College, 1600 Campus Road, Los Angeles, CA 90041, USA
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Blicher A, Wodzinska K, Fidorra M, Winterhalter M, Heimburg T. The temperature dependence of lipid membrane permeability, its quantized nature, and the influence of anesthetics. Biophys J 2009; 96:4581-91. [PMID: 19486680 DOI: 10.1016/j.bpj.2009.01.062] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 01/12/2009] [Accepted: 01/13/2009] [Indexed: 10/20/2022] Open
Abstract
We investigate the permeability of lipid membranes for fluorescence dyes and ions. We find that permeability reaches a maximum close to the chain melting transition of the membranes. Close to transitions, fluctuations in area and compressibility are high, leading to an increased likelihood of spontaneous lipid pore formation. Fluorescence correlation spectroscopy reveals the permeability for rhodamine dyes across 100-nm vesicles. Using fluorescence correlation spectroscopy, we find that the permeability of vesicle membranes for fluorescence dyes is within error proportional to the excess heat capacity. To estimate defect size we measure the conductance of solvent-free planar lipid bilayer. Microscopically, we show that permeation events appear as quantized current events very similar to those reported for channel proteins. Further, we demonstrate that anesthetics lead to a change in membrane permeability that can be predicted from their effect on heat capacity profiles. Depending on temperature, the permeability can be enhanced or reduced. We demonstrate that anesthetics decrease channel conductance and ultimately lead to blocking of the lipid pores in experiments performed at or above the chain melting transition. Our data suggest that the macroscopic increase in permeability close to transitions and microscopic lipid ion channel formation are the same physical process.
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Affiliation(s)
- Andreas Blicher
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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Wunderlich B, Leirer C, Idzko AL, Keyser UF, Wixforth A, Myles VM, Heimburg T, Schneider MF. Phase-state dependent current fluctuations in pure lipid membranes. Biophys J 2009; 96:4592-7. [PMID: 19486681 DOI: 10.1016/j.bpj.2009.02.053] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Revised: 01/20/2009] [Accepted: 02/20/2009] [Indexed: 10/20/2022] Open
Abstract
Current fluctuations in pure lipid membranes have been shown to occur under the influence of transmembrane electric fields (electroporation) as well as a result from structural rearrangements of the lipid bilayer during phase transition (soft perforation). We demonstrate that the ion permeability during lipid phase transition exhibits the same qualitative temperature dependence as the macroscopic heat capacity of a D15PC/DOPC vesicle suspension. Microscopic current fluctuations show distinct characteristics for each individual phase state. Although current fluctuations in the fluid phase show spikelike behavior of short timescales (approximately 2 ms) with a narrow amplitude distribution, the current fluctuations during lipid phase transition appear in distinct steps with timescales of approximately 20 ms. We propose a theoretical explanation for the origin of timescales and permeability based on a linear relationship between lipid membrane susceptibilities and relaxation times near the phase transition.
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Affiliation(s)
- B Wunderlich
- University of Augsburg, Experimental Physics I, Augsburg, Germany
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Potekhin S, Senin A, Abdurakhmanov N, Khusainova R. High pressure effect on the main transition from the ripple gel P′β phase to the liquid crystal (Lα) phase in dipalmitoylphosphatidylcholine. Microcalorimetric study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2588-93. [DOI: 10.1016/j.bbamem.2008.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 07/31/2008] [Accepted: 08/04/2008] [Indexed: 11/30/2022]
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Oliynyk V, Jäger M, Heimburg T, Buckin V, Kaatze U. Lipid membrane domain formation and alamethicin aggregation studied by calorimetry, sound velocity measurements, and atomic force microscopy. Biophys Chem 2008; 134:168-77. [DOI: 10.1016/j.bpc.2008.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 02/07/2008] [Accepted: 02/09/2008] [Indexed: 11/29/2022]
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