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Jaksch S, Lipfert F, Koutsioubas A, Mattauch S, Holderer O, Ivanova O, Frielinghaus H, Hertrich S, Fischer SF, Nickel B. Influence of ibuprofen on phospholipid membranes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:022716. [PMID: 25768540 DOI: 10.1103/physreve.91.022716] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Indexed: 06/04/2023]
Abstract
A basic understanding of biological membranes is of paramount importance as these membranes comprise the very building blocks of life itself. Cells depend in their function on a range of properties of the membrane, which are important for the stability and function of the cell, information and nutrient transport, waste disposal, and finally the admission of drugs into the cell and also the deflection of bacteria and viruses. We have investigated the influence of ibuprofen on the structure and dynamics of L-α-phosphatidylcholine (SoyPC) membranes by means of grazing incidence small-angle neutron scattering, neutron reflectometry, and grazing incidence neutron spin echo spectroscopy. From the results of these experiments, we were able to determine that ibuprofen induces a two-step structuring behavior in the SoyPC films, where the structure evolves from the purely lamellar phase for pure SoyPC over a superposition of two hexagonal phases to a purely hexagonal phase at high concentrations. A relaxation, which is visible when no ibuprofen is present in the membrane, vanishes upon addition of ibuprofen. This we attribute to a stiffening of the membrane. This behavior may be instrumental in explaining the toxic behavior of ibuprofen in long-term application.
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Affiliation(s)
- Sebastian Jaksch
- Forschungszentrum Jülich GmbH, JCNS at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - Frederik Lipfert
- Forschungszentrum Jülich GmbH, JCNS at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - Alexandros Koutsioubas
- Forschungszentrum Jülich GmbH, JCNS at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - Stefan Mattauch
- Forschungszentrum Jülich GmbH, JCNS at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - Olaf Holderer
- Forschungszentrum Jülich GmbH, JCNS at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - Oxana Ivanova
- Forschungszentrum Jülich GmbH, JCNS at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - Henrich Frielinghaus
- Forschungszentrum Jülich GmbH, JCNS at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - Samira Hertrich
- Ludwig-Maximilians-Universität, Department für Physik und CeNS, Geschwister-Scholl-Platz 1, D-80539 München, Germany
| | - Stefan F Fischer
- Ludwig-Maximilians-Universität, Department für Physik und CeNS, Geschwister-Scholl-Platz 1, D-80539 München, Germany
| | - Bert Nickel
- Ludwig-Maximilians-Universität, Department für Physik und CeNS, Geschwister-Scholl-Platz 1, D-80539 München, Germany
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Yu H, Yzeiri I, Hou B, Chen CH, Bu W, Vanysek P, Chen YS, Lin B, Král P, Schlossman ML. Electric Field Effect on Phospholipid Monolayers at an Aqueous-Organic Liquid-Liquid Interface. J Phys Chem B 2014; 119:9319-34. [PMID: 25289837 DOI: 10.1021/jp5098525] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electric potential difference across cell membranes, known as the membrane potential, plays an important role in the activation of many biological processes. To investigate the effect of the membrane potential on the molecular ordering of lipids within a biomimetic membrane, a self-assembled monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) lipids at an electrified 1,2-dichloroethane/water interface is studied with X-ray reflectivity and interfacial tension. Measurements over a range of electric potential differences, -150 to +130 mV, that encompass the range of typical biomembrane potentials demonstrate a nearly constant and stable structure whose lipid interfacial density is comparable to that found in other biomimetic membrane systems. Measurements at higher positive potentials, up to 330 mV, illustrate a monotonic decrease in the lipid interfacial density and accompanying variations in the interfacial configuration of the lipid. Molecular dynamics simulations, designed to mimic the experimental conditions, show that the measured changes in lipid configuration are due primarily to the variation in area per lipid with increasing applied electric field. Rotation of the SOPC dipole moment by the torque from the applied electric field appears to be negligible, except at the highest measured potentials. The simulations confirm in atomistic detail the measured potential-dependent characteristics of SOPC monolayers. Our hybrid study sheds light on phospholipid monolayer stability under different membrane potentials, which is important for understanding membrane processes. This study also illustrates the use of X-ray surface scattering to probe the ordering of surfactant monolayers at an electrified aqueous-organic liquid-liquid interface.
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Affiliation(s)
- Hao Yu
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Irena Yzeiri
- ‡Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Binyang Hou
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Chiu-Hao Chen
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Wei Bu
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | | | - Yu-Sheng Chen
- ∥The Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- ∥The Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States
| | - Petr Král
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States.,‡Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Mark L Schlossman
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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Tronin A, Nordgren CE, Strzalka JW, Kuzmenko I, Worcester DL, Lauter V, Freites JA, Tobias DJ, Blasie JK. Direct evidence of conformational changes associated with voltage gating in a voltage sensor protein by time-resolved X-ray/neutron interferometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4784-4796. [PMID: 24697545 PMCID: PMC4007984 DOI: 10.1021/la500560w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Indexed: 06/03/2023]
Abstract
The voltage sensor domain (VSD) of voltage-gated cation (e.g., Na(+), K(+)) channels central to neurological signal transmission can function as a distinct module. When linked to an otherwise voltage-insensitive, ion-selective membrane pore, the VSD imparts voltage sensitivity to the channel. Proteins homologous with the VSD have recently been found to function themselves as voltage-gated proton channels or to impart voltage sensitivity to enzymes. Determining the conformational changes associated with voltage gating in the VSD itself in the absence of a pore domain thereby gains importance. We report the direct measurement of changes in the scattering-length density (SLD) profile of the VSD protein, vectorially oriented within a reconstituted phospholipid bilayer membrane, as a function of the transmembrane electric potential by time-resolved X-ray and neutron interferometry. The changes in the experimental SLD profiles for both polarizing and depolarizing potentials with respect to zero potential were found to extend over the entire length of the isolated VSD's profile structure. The characteristics of the changes observed were in qualitative agreement with molecular dynamics simulations of a related membrane system, suggesting an initial interpretation of these changes in terms of the VSD's atomic-level 3-D structure.
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Affiliation(s)
- Andrey
Y. Tronin
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - C. Erik Nordgren
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joseph W. Strzalka
- X-ray
Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Ivan Kuzmenko
- X-ray
Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - David L. Worcester
- Department
of Physiology & Biophysics, University
of California Irvine, Irvine, California 92697, United States
| | - Valeria Lauter
- Spallation
Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - J. Alfredo Freites
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Douglas J. Tobias
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - J. Kent Blasie
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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