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Sato M, Hariyama M, Komiya M, Suzuki K, Tozawa Y, Yamamoto H, Hirano-Iwata A. Model-free idealization: Adaptive integrated approach for idealization of ion-channel currents. Biophys J 2023; 122:3959-3975. [PMID: 37634080 PMCID: PMC10560676 DOI: 10.1016/j.bpj.2023.08.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 04/21/2023] [Accepted: 08/24/2023] [Indexed: 08/28/2023] Open
Abstract
Single-channel electrophysiological recordings provide insights into transmembrane ion permeation and channel gating mechanisms. The first step in the analysis of the recorded currents involves an "idealization" process, in which noisy raw data are classified into two discrete levels corresponding to the open and closed states of channels. This provides valuable information on the gating kinetics of ion channels. However, the idealization step is often challenging in cases of currents with poor signal-to-noise ratios and baseline drifts, especially when the gating model of the target channel is not identified. We report herein on a highly robust model-free idealization method for achieving this goal. The algorithm, called adaptive integrated approach for idealization of ion-channel currents (AI2), is composed of Kalman filter and Gaussian mixture model clustering and functions without user input. AI2 automatically determines the noise reduction setting based on the degree of separation between the open and closed levels. We validated the method on pseudo-channel-current datasets that contain either computed or experimentally recorded noise. We also investigated the relationship between the noise reduction parameter of the Kalman filter and the cutoff frequency of the low-pass filter. The AI2 algorithm was then tested on actual experimental data for biological channels including gramicidin A, a voltage-gated sodium channel, and other unidentified channels. We compared the idealization results with those obtained by the conventional methods, including the 50%-threshold-crossing method.
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Affiliation(s)
- Madoka Sato
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi, Japan
| | - Masanori Hariyama
- Graduate School of Information Sciences, Tohoku University, Sendai, Miyagi, Japan.
| | - Maki Komiya
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi, Japan
| | - Kae Suzuki
- Graduate School of Science and Engineering, Saitama University, Saitama, Japan; Epsilon Molecular Engineering, Inc, Open Innovation Center in Saitama University, Saitama, Japan
| | - Yuzuru Tozawa
- Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Hideaki Yamamoto
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi, Japan
| | - Ayumi Hirano-Iwata
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi, Japan; Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi, Japan; Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, Miyagi, Japan.
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2
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Rovini A, Gurnev PA, Beilina A, Queralt-Martín M, Rosencrans W, Cookson MR, Bezrukov SM, Rostovtseva TK. Molecular mechanism of olesoxime-mediated neuroprotection through targeting α-synuclein interaction with mitochondrial VDAC. Cell Mol Life Sci 2020; 77:3611-3626. [PMID: 31760463 PMCID: PMC7244372 DOI: 10.1007/s00018-019-03386-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 10/23/2019] [Accepted: 11/13/2019] [Indexed: 01/03/2023]
Abstract
An intrinsically disordered neuronal protein α-synuclein (αSyn) is known to cause mitochondrial dysfunction, contributing to loss of dopaminergic neurons in Parkinson's disease. Through yet poorly defined mechanisms, αSyn crosses mitochondrial outer membrane and targets respiratory complexes leading to bioenergetics defects. Here, using neuronally differentiated human cells overexpressing wild-type αSyn, we show that the major metabolite channel of the outer membrane, the voltage-dependent anion channel (VDAC), is a pathway for αSyn translocation into the mitochondria. Importantly, the neuroprotective cholesterol-like synthetic compound olesoxime inhibits this translocation. By applying complementary electrophysiological and biophysical approaches, we provide mechanistic insights into the interplay between αSyn, VDAC, and olesoxime. Our data suggest that olesoxime interacts with VDAC β-barrel at the lipid-protein interface thus hindering αSyn translocation through the VDAC pore and affecting VDAC voltage gating. We propose that targeting αSyn translocation through VDAC could represent a key mechanism for the development of new neuroprotective strategies.
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Affiliation(s)
- Amandine Rovini
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bldg. 29B, Room 1G09, Bethesda, MD, 20892-0924, USA
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Philip A Gurnev
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bldg. 29B, Room 1G09, Bethesda, MD, 20892-0924, USA
| | - Alexandra Beilina
- Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute of Aging, National Institutes of Health, Bethesda, MD, 20892, USA
| | - María Queralt-Martín
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bldg. 29B, Room 1G09, Bethesda, MD, 20892-0924, USA
| | - William Rosencrans
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bldg. 29B, Room 1G09, Bethesda, MD, 20892-0924, USA
- Colgate University, Hamilton, NY, 13346, USA
| | - Mark R Cookson
- Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute of Aging, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sergey M Bezrukov
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bldg. 29B, Room 1G09, Bethesda, MD, 20892-0924, USA
| | - Tatiana K Rostovtseva
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bldg. 29B, Room 1G09, Bethesda, MD, 20892-0924, USA.
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Rostovtseva TK, Queralt-Martín M, Rosencrans WM, Bezrukov SM. Targeting the Multiple Physiologic Roles of VDAC With Steroids and Hydrophobic Drugs. Front Physiol 2020; 11:446. [PMID: 32457654 PMCID: PMC7221028 DOI: 10.3389/fphys.2020.00446] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/09/2020] [Indexed: 12/12/2022] Open
Abstract
There is accumulating evidence that endogenous steroids and non-polar drugs are involved in the regulation of mitochondrial physiology. Many of these hydrophobic compounds interact with the Voltage Dependent Anion Channel (VDAC). This major metabolite channel in the mitochondrial outer membrane (MOM) regulates the exchange of ions and water-soluble metabolites, such as ATP and ADP, across the MOM, thus governing mitochondrial respiration. Proteomics and biochemical approaches together with molecular dynamics simulations have identified an impressively large number of non-polar compounds, including endogenous, able to bind to VDAC. These findings have sparked speculation that both natural steroids and synthetic hydrophobic drugs regulate mitochondrial physiology by directly affecting VDAC ion channel properties and modulating its metabolite permeability. Here we evaluate recent studies investigating the effect of identified VDAC-binding natural steroids and non-polar drugs on VDAC channel functioning. We argue that while many compounds are found to bind to the VDAC protein, they do not necessarily affect its channel functions in vitro. However, they may modify other aspects of VDAC physiology such as interaction with its cytosolic partner proteins or complex formation with other mitochondrial membrane proteins, thus altering mitochondrial function.
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Affiliation(s)
- Tatiana K Rostovtseva
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - María Queralt-Martín
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - William M Rosencrans
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Sergey M Bezrukov
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
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4
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Zakharova AA, Efimova SS, Schagina LV, Malev VV, Ostroumova OS. Blocking ion channels induced by antifungal lipopeptide syringomycin E with amide-linked local anesthetics. Sci Rep 2018; 8:11543. [PMID: 30069037 PMCID: PMC6070474 DOI: 10.1038/s41598-018-30077-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 07/24/2018] [Indexed: 11/22/2022] Open
Abstract
The effects of the amide-linked (lidocaine (LDC), mepivacaine (MPV), prilocaine (PLC)) and ester-bound local anesthetics (benzocaine (BZC), procaine (PRC), and tetracaine (TTC)) on the pore-forming activity of the antifungal lipopeptide syringomycin E (SRE) in lipid bilayers were studied. Independently on electrolyte concentration in the membrane bathing solution the observed changes in conductance of SRE channels agreed with the altered membrane dipole potential under the action of ester-bound local anesthetics. Effects of aminoamides in diluted and concentrated solutions were completely different. At 0.1 M KCl (pH 7.4) the effects of amide-linked anesthetics were in accordance with changes in the membrane surface potential, while at 2 M KCl aminoamides blocked ion passage through the SRE channels, leading to sharp reductions in pore conductance at negative voltages and 100-fold decreases in the channel lifetimes. The effects were not practically influenced by the membrane lipid composition. The interaction cooperativity implied the existence of specific binding sites for amide-bound anesthetics in SRE channels.
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Affiliation(s)
- Anastasiia A Zakharova
- Institute of Cytology of the Russian Academy of Sciences, 4 Tikhoretsky prospect, St. Petersburg, 194064, Russia
| | - Svetlana S Efimova
- Institute of Cytology of the Russian Academy of Sciences, 4 Tikhoretsky prospect, St. Petersburg, 194064, Russia
| | - Ludmila V Schagina
- Institute of Cytology of the Russian Academy of Sciences, 4 Tikhoretsky prospect, St. Petersburg, 194064, Russia
| | - Valery V Malev
- Institute of Cytology of the Russian Academy of Sciences, 4 Tikhoretsky prospect, St. Petersburg, 194064, Russia.,Saint Petersburg State University, Institute of Chemistry, 26 Universitetskii prospect, St. Petersburg, Petergof, 198504, Russia
| | - Olga S Ostroumova
- Institute of Cytology of the Russian Academy of Sciences, 4 Tikhoretsky prospect, St. Petersburg, 194064, Russia.
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Weinrich M, Worcester DL, Bezrukov SM. Lipid nanodomains change ion channel function. NANOSCALE 2017; 9:13291-13297. [PMID: 28858358 PMCID: PMC5599369 DOI: 10.1039/c7nr03926c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Signaling proteins and neurotransmitter receptors often associate with saturated chain and cholesterol-rich domains of cell membranes, also known as lipid rafts. The saturated chains and high cholesterol environment in lipid rafts can modulate protein function, but evidence for such modulation of ion channel function in lipid rafts is lacking. Here, using raft-forming model membrane systems containing cholesterol, we show that lipid lateral phase separation at the nanoscale level directly affects the dissociation kinetics of the gramicidin dimer, a model ion channel.
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Affiliation(s)
- Michael Weinrich
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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6
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Weiser BP, Bu W, Wong D, Eckenhoff RG. Sites and functional consequence of VDAC-alkylphenol anesthetic interactions. FEBS Lett 2014; 588:4398-403. [PMID: 25448677 DOI: 10.1016/j.febslet.2014.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 09/10/2014] [Accepted: 10/10/2014] [Indexed: 10/24/2022]
Abstract
General anesthetics have previously been shown to bind mitochondrial VDAC. Here, using a photoactive analog of the anesthetic propofol, we determined that alkylphenol anesthetics bind to Gly56 and Val184 on rat VDAC1. By reconstituting rat VDAC into planar bilayers, we determined that propofol potentiates VDAC gating with asymmetry at the voltage polarities; in contrast, propofol does not affect the conductance of open VDAC. Additional experiments showed that propofol also does not affect gramicidin A properties that are sensitive to lipid bilayer mechanics. Together, this suggests propofol affects VDAC function through direct protein binding, likely at the lipid-exposed channel surface, and that gating can be modulated by ligand binding to the distal ends of VDAC β-strands where Gly56 and Val184 are located.
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Affiliation(s)
- Brian P Weiser
- Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, United States; Department of Pharmacology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, United States
| | - Weiming Bu
- Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, United States
| | - David Wong
- Drexel University College of Medicine, Philadelphia, PA 19129, United States
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, United States.
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Nwaneshiudu IC, Nwaneshiudu CA, Schwartz DT. Separation and enhanced detection of anesthetic compounds using solid phase micro-extraction (SPME)-Raman spectroscopy. APPLIED SPECTROSCOPY 2014; 68:1254-1259. [PMID: 25285420 DOI: 10.1366/13-07362] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Polydimethylsiloxane (PDMS)-based solid-phase micro-extraction (SPME) was used along with Raman spectroscopy (RS) to separate and enhance the detection of five anesthetic compounds (halothane, propofol, isoflurane, enflurane, and etomidate) from aqueous and serum phases. Raman signals in the spectral ranges 250-450 cm(-1) and 950-1050 cm(-1) allowed the unique characterization of all five compounds when extracted into the PDMS phase. The SPME-RS detection of clinically relevant concentrations of aqueous propofol (6.5 μM) and halothane (200 μM) is shown. We quantify the partition coefficient for aqueous halothane in PDMS as log K = 1.9 ± 0.2. Solid-phase micro-extraction of the anesthetics makes their detection possible without the strong autofluorescent interference of serum proteins. Because of low solubility and/or weak Raman scattering, we found it challenging to detect enflurane, isoflurane, and etomidate directly from the aqueous phase, but could we do so with SPME enhancement. These studies show the potential of SPME-RS as a method for the direct detection of anesthetics in blood.
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Affiliation(s)
- Ikechukwu C Nwaneshiudu
- University of Washington, Department of Chemical Engineering, Box 351750, Seattle, WA 98195, USA
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8
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Sugawara M, Shoji A, Sakamoto M. Pore-forming compounds as signal transduction elements for highly sensitive biosensing. ANAL SCI 2014; 30:119-28. [PMID: 24420253 DOI: 10.2116/analsci.30.119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Pore-forming compounds are attracting much attention due to the signal transduction ability for the development of highly sensitive biosensing. In this review, we describe an overview of the recent advances made by our group in the design of molecular sensing interfaces of spherical and planar lipid bilayers and natural bilayers. The potential uses of pore-forming compounds, such as gramicidin and MCM-41, in lipid bilayers and natural glutamate receptor channels in biomembrane are presented.
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Affiliation(s)
- Masao Sugawara
- Department of Chemistry, College of Humanities and Sciences, Nihon University
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Raju SG, Barber AF, LeBard DN, Klein ML, Carnevale V. Exploring volatile general anesthetic binding to a closed membrane-bound bacterial voltage-gated sodium channel via computation. PLoS Comput Biol 2013; 9:e1003090. [PMID: 23785267 PMCID: PMC3681623 DOI: 10.1371/journal.pcbi.1003090] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/26/2013] [Indexed: 01/07/2023] Open
Abstract
Despite the clinical ubiquity of anesthesia, the molecular basis of anesthetic action is poorly understood. Amongst the many molecular targets proposed to contribute to anesthetic effects, the voltage gated sodium channels (VGSCs) should also be considered relevant, as they have been shown to be sensitive to all general anesthetics tested thus far. However, binding sites for VGSCs have not been identified. Moreover, the mechanism of inhibition is still largely unknown. The recently reported atomic structures of several members of the bacterial VGSC family offer the opportunity to shed light on the mechanism of action of anesthetics on these important ion channels. To this end, we have performed a molecular dynamics "flooding" simulation on a membrane-bound structural model of the archetypal bacterial VGSC, NaChBac in a closed pore conformation. This computation allowed us to identify binding sites and access pathways for the commonly used volatile general anesthetic, isoflurane. Three sites have been characterized with binding affinities in a physiologically relevant range. Interestingly, one of the most favorable sites is in the pore of the channel, suggesting that the binding sites of local and general anesthetics may overlap. Surprisingly, even though the activation gate of the channel is closed, and therefore the pore and the aqueous compartment at the intracellular side are disconnected, we observe binding of isoflurane in the central cavity. Several sampled association and dissociation events in the central cavity provide consistent support to the hypothesis that the "fenestrations" present in the membrane-embedded region of the channel act as the long-hypothesized hydrophobic drug access pathway.
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Affiliation(s)
- S. G. Raju
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Annika F. Barber
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - David N. LeBard
- Department of Chemistry, Yeshiva University, New York, New York, United States of America
| | - Michael L. Klein
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
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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: 53] [Impact Index Per Article: 4.8] [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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Nelson SC, Neeley SK, Melonakos ED, Bell JD, Busath DD. Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane. BMC BIOPHYSICS 2012; 5:5. [PMID: 22444827 PMCID: PMC3359235 DOI: 10.1186/2046-1682-5-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 03/24/2012] [Indexed: 12/02/2022]
Abstract
Background The mechanism of action of volatile general anesthetics has not yet been resolved. In order to identify the effects of isoflurane on the membrane, we measured the steady-state anisotropy of two fluorescent probes that reside at different depths. Incorporation of anesthetic was confirmed by shifting of the main phase transition temperature. Results In liquid crystalline dipalmitoylphosphatidylcholine liposomes, isoflurane (7-25 mM in the bath) increases trimethylammonium-diphenylhexatriene fluorescence anisotropy by ~0.02 units and decreases diphenylhexatriene anisotropy by the same amount. Conclusions The anisotropy data suggest that isoflurane decreases non-axial dye mobility in the headgroup region, while increasing it in the tail region. We propose that these results reflect changes in the lateral pressure profile of the membrane.
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Affiliation(s)
- Steven C Nelson
- WIDB 574, Dept, of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA.
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12
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Weinrich M, Nanda H, Worcester DL, Majkrzak CF, Maranville BB, Bezrukov SM. Halothane changes the domain structure of a binary lipid membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:4723-8. [PMID: 22352350 PMCID: PMC3302933 DOI: 10.1021/la204317k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
X-ray and neutron diffraction studies of a binary lipid membrane demonstrate that halothane at physiological concentrations produces a pronounced redistribution of lipids between domains of different lipid types identified by different lamellar d-spacings and isotope composition. In contrast, dichlorohexafluorocyclobutane (F6), a halogenated nonanesthetic, does not produce such significant effects. These findings demonstrate a specific effect of inhalational anesthetics on mixing phase equilibria of a lipid mixture.
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Affiliation(s)
- Michael Weinrich
- National Center for Medical Rehabilitation Research, Eunice Kennedy Shriver Institute of Child Health and Human Development, Bethesda, Maryland, United States.
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NISHIO M, SHOJI A, SUGAWARA M. Planar Lipid Bilayers Containing Gramicidin A as a Molecular Sensing System Based on an Integrated Current. ANAL SCI 2012; 28:661-7. [DOI: 10.2116/analsci.28.661] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Masato NISHIO
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Atsushi SHOJI
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Masao SUGAWARA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
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14
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Lundbaek JA, Collingwood SA, Ingólfsson HI, Kapoor R, Andersen OS. Lipid bilayer regulation of membrane protein function: gramicidin channels as molecular force probes. J R Soc Interface 2009; 7:373-95. [PMID: 19940001 DOI: 10.1098/rsif.2009.0443] [Citation(s) in RCA: 226] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Membrane protein function is regulated by the host lipid bilayer composition. This regulation may depend on specific chemical interactions between proteins and individual molecules in the bilayer, as well as on non-specific interactions between proteins and the bilayer behaving as a physical entity with collective physical properties (e.g. thickness, intrinsic monolayer curvature or elastic moduli). Studies in physico-chemical model systems have demonstrated that changes in bilayer physical properties can regulate membrane protein function by altering the energetic cost of the bilayer deformation associated with a protein conformational change. This type of regulation is well characterized, and its mechanistic elucidation is an interdisciplinary field bordering on physics, chemistry and biology. Changes in lipid composition that alter bilayer physical properties (including cholesterol, polyunsaturated fatty acids, other lipid metabolites and amphiphiles) regulate a wide range of membrane proteins in a seemingly non-specific manner. The commonality of the changes in protein function suggests an underlying physical mechanism, and recent studies show that at least some of the changes are caused by altered bilayer physical properties. This advance is because of the introduction of new tools for studying lipid bilayer regulation of protein function. The present review provides an introduction to the regulation of membrane protein function by the bilayer physical properties. We further describe the use of gramicidin channels as molecular force probes for studying this mechanism, with a unique ability to discriminate between consequences of changes in monolayer curvature and bilayer elastic moduli.
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Affiliation(s)
- Jens A Lundbaek
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA.
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