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Vanuytsel S, Carniello J, Wallace MI. Artificial Signal Transduction across Membranes. Chembiochem 2019; 20:2569-2580. [DOI: 10.1002/cbic.201900254] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 07/09/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Steven Vanuytsel
- Department of ChemistryKing's College London Britannia House 7 Trinity Street London SE1 1DB UK
- London Centre for Nanotechnology Strand London WC2R 2LS UK
| | - Joanne Carniello
- Department of ChemistryKing's College London Britannia House 7 Trinity Street London SE1 1DB UK
- London Centre for Nanotechnology Strand London WC2R 2LS UK
| | - Mark Ian Wallace
- Department of ChemistryKing's College London Britannia House 7 Trinity Street London SE1 1DB UK
- London Centre for Nanotechnology Strand London WC2R 2LS UK
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2
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Noshiro D, Sonomura K, Yu HH, Imanishi M, Asami K, Futaki S. Construction of a Ca(2+)-gated artificial channel by fusing alamethicin with a calmodulin-derived extramembrane segment. Bioconjug Chem 2013; 24:188-95. [PMID: 23272973 DOI: 10.1021/bc300468x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Using native chemical ligation, we constructed a Ca(2+)-gated fusion channel protein consisting of alamethicin and the C-terminal domain of calmodulin. At pH 5.4 and in the absence of Ca(2+), this fusion protein yielded a burst-like channel current with no discrete channel conductance levels. However, Ca(2+) significantly lengthened the specific channel open state and increased the mean channel current, while Mg(2+) produced no significant changes in the channel current. On the basis of 8-anilinonaphthalene-1-sulfonic acid (ANS) fluorescent measurement, Ca(2+)-stimulated gating may be related to an increased surface hydrophobicity of the extramembrane segment of the fusion protein.
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Affiliation(s)
- Daisuke Noshiro
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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3
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Noshiro D, Asami K, Futaki S. Control of leakage activities of alamethicin analogs by metals: Side chain-dependent adverse gating response to Zn2+. Bioorg Med Chem 2012; 20:6870-6. [DOI: 10.1016/j.bmc.2012.09.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 09/16/2012] [Accepted: 09/17/2012] [Indexed: 10/27/2022]
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4
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Hjørringgaard CU, Vad BS, Matchkov VV, Nielsen SB, Vosegaard T, Nielsen NC, Otzen DE, Skrydstrup T. Cyclodextrin-scaffolded alamethicin with remarkably efficient membrane permeabilizing properties and membrane current conductance. J Phys Chem B 2012; 116:7652-9. [PMID: 22676384 DOI: 10.1021/jp2098679] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Bacterial resistance to classical antibiotics is a serious medical problem, which continues to grow. Small antimicrobial peptides represent a potential solution and are increasingly being developed as novel therapeutic agents. Many of these peptides owe their antibacterial activity to the formation of trans-membrane ion-channels resulting in cell lysis. However, to further develop the field of peptide antibiotics, a thorough understanding of their mechanism of action is needed. Alamethicin belongs to a class of peptides called peptaibols and represents one of these antimicrobial peptides. To examine the dynamics of assembly and to facilitate a thorough structural evaluation of the alamethicin ion-channels, we have applied click chemistry for the synthesis of templated alamethicin multimers covalently attached to cyclodextrin-scaffolds. Using oriented circular dichroism, calcein release assays, and single-channel current measurements, the α-helices of the templated multimers were demonstrated to insert into lipid bilayers forming highly efficient and remarkably stable ion-channels.
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Affiliation(s)
- Claudia U Hjørringgaard
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
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5
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Prangkio P, Rao DK, Lance KD, Rubinshtein M, Yang J, Mayer M. Self-assembled, cation-selective ion channels from an oligo(ethylene glycol) derivative of benzothiazole aniline. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2877-85. [PMID: 21889925 DOI: 10.1016/j.bbamem.2011.08.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 07/22/2011] [Accepted: 08/18/2011] [Indexed: 01/01/2023]
Abstract
This paper describes the spontaneous formation of well-defined pores in planar lipid bilayers from the self-assembly of a small synthetic molecule that contains a benzothiazole aniline (BTA) group attached to a tetra-ethylene glycol (EG4) moiety. Macroscopic and single-channel current recordings suggest that these pores are formed by the assembly of four BTA-EG4 monomers with an open pore diameter that appears similar to the one of gramicidin pores (~0.4 nm). The single-channel conductance of these pores is modulated by the pH of the electrolyte and has a minimum at pH~3. Self-assembled pores from BTA-EG4 are selective for monovalent cations and have long open channel lifetimes on the order of seconds. BTA-EG4 monomers in these pores appear to be arranged symmetrically across both leaflets of the bilayer, and spectroscopy studies suggest that the fluorescent BTA group is localized inside the lipid bilayers. In terms of biological activity, BTA-EG4 molecules inhibited growth of gram-positive Bacillus subtilis bacteria (IC50~50 μM) and human neuroblastoma SH-SY5Y cells (IC50~60 μM), while they were not toxic to gram-negative Escherichia coli bacteria at a concentration up to 500 μM. Based on these properties, this drug-like, synthetic, pore-forming molecule with a molecular weight below 500 g mol(-1) might be appealing as a starting material for development of antibiotics or membrane-permeating moieties for drug delivery. From a biophysical point of view, long-lived, well-defined ion-selective pores from BTA-EG4 molecules offer an example of a self-assembled synthetic supramolecule with biological function.
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Affiliation(s)
- Panchika Prangkio
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109-2110, USA
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6
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Noshiro D, Asami K, Futaki S. Metal-assisted channel stabilization: disposition of a single histidine on the N-terminus of alamethicin yields channels with extraordinarily long lifetimes. Biophys J 2010; 98:1801-8. [PMID: 20441743 DOI: 10.1016/j.bpj.2010.01.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 11/08/2009] [Accepted: 01/04/2010] [Indexed: 10/19/2022] Open
Abstract
Alamethicin, a member of the peptaibol family of antibiotics, is a typical channel-forming peptide with a helical structure. The self-assembly of the peptide in the membranes yields voltage-dependent channels. In this study, three alamethicin analogs possessing a charged residue (His, Lys, or Glu) on their N-termini were designed with the expectation of stabilizing the transmembrane structure. A slight elongation of channel lifetime was observed for the Lys and Glu analogs. On the other hand, extensive stabilization of certain channel open states was observed for the His analog. This stabilization was predominantly observed in the presence of metal ions such as Zn(2+), suggesting that metal coordination with His facilitates the formation of a supramolecular assembly in the membranes. Channel stability was greatly diminished by acetylation of the N-terminal amino group, indicating that the N-terminal amino group also plays an important role in metal coordination.
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Affiliation(s)
- Daisuke Noshiro
- Institute for Chemical Research, Kyoto University, Kyoto, Japan
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7
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Structural changes induced in thionins by chloride anions as determined by molecular dynamics simulations. Biophys Chem 2010; 147:42-52. [DOI: 10.1016/j.bpc.2009.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 12/21/2009] [Accepted: 12/23/2009] [Indexed: 11/23/2022]
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8
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Mayer M, Semetey V, Gitlin I, Yang J, Whitesides GM. Using ion channel-forming peptides to quantify protein-ligand interactions. J Am Chem Soc 2008; 130:1453-65. [PMID: 18179217 DOI: 10.1021/ja077555f] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper proposes a method for sensing affinity interactions by triggering disruption of self-assembly of ion channel-forming peptides in planar lipid bilayers. It shows that the binding of a derivative of alamethicin carrying a covalently attached sulfonamide ligand to carbonic anhydrase II (CA II) resulted in the inhibition of ion channel conductance through the bilayer. We propose that the binding of the bulky CA II protein (MW approximately 30 kD) to the ion channel-forming peptides (MW approximately 2.5 kD) either reduced the tendency of these peptides to self-assemble into a pore or extracted them from the bilayer altogether. In both outcomes, the interactions between the protein and the ligand lead to a disruption of self-assembled pores. Addition of a competitive inhibitor, 4-carboxybenzenesulfonamide, to the solution released CA II from the alamethicin-sulfonamide conjugate and restored the current flow across the bilayer by allowing reassembly of the ion channels in the bilayer. Time-averaged recordings of the current over discrete time intervals made it possible to quantify this monovalent ligand binding interaction. This method gave a dissociation constant of approximately 2 microM for the binding of CA II to alamethicin-sulfonamide in the bilayer recording chamber: this value is consistent with a value obtained independently with CA II and a related sulfonamide derivative by isothermal titration calorimetry.
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Affiliation(s)
- Michael Mayer
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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9
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Kiwada T, Sonomura K, Sugiura Y, Asami K, Futaki S. Transmission of extramembrane conformational change into current: construction of metal-gated ion channel. J Am Chem Soc 2007; 128:6010-1. [PMID: 16669650 DOI: 10.1021/ja060515b] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Interaction with Fe(III) induces the reversible conformational switch of the extramembrane segment in the artificial receptor channel, which is transmitted into membranes as an increase in channel current (ion flux).
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Affiliation(s)
- Tatsuto Kiwada
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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10
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Futaki S, Asami K. Ligand-induced extramembrane conformation switch controlling alamethicin assembly and the channel current. Chem Biodivers 2007; 4:1313-22. [PMID: 17589883 DOI: 10.1002/cbdv.200790112] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this review, we describe our approach to creating artificial receptor-channel proteins or sensor systems, using an extramembrane segment conformationally switchable by external stimuli. Alamethicin is known to self-assemble in membranes to form ion channels with various open states. Employment of an alpha-helical leucine-zipper segment resulted in the effective modulation of the association states of alamethicin to produce a single predominant channel-open state. A decrease in the helical content of the extramembrane segments was found to induce a channel-current increase. Therefore, conformational changes in the extramembrane segments induced by the interaction with ligands can be reflected in the current levels.
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Affiliation(s)
- Shiroh Futaki
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan.
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11
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Pashkovskaya AA, Lukashev EP, Antonov PE, Finogenova OA, Ermakov YA, Melik-Nubarov NS, Antonenko YN. Grafting of polylysine with polyethylenoxide prevents demixing of O-pyromellitylgramicidin in lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1685-95. [PMID: 16901462 DOI: 10.1016/j.bbamem.2006.06.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Revised: 05/19/2006] [Accepted: 06/06/2006] [Indexed: 01/24/2023]
Abstract
Both natural and synthetic polycations can induce demixing of negatively charged components in artificial and possibly in natural membranes. This process can result in formation of clusters (binding of several components to a polycation chain) and/or domains (aggregation of clusters and formation of a separate phase enriched in some particular component). In order to distinguish between these two phenomena, a model lipid membrane system containing ion channels, formed by a negatively charged peptide, O-pyromellitylgramicidin, and polycations of different structures was used. Microelectrophoresis of liposomes, changes in boundary potential of planar bilayers, the shape of compression curves and potentials of lipid and lipid/peptide monolayers were used to monitor the electrostatic factors in polymer adsorption to the membrane and peptide-polymer interactions. The synthesized PEO-grafted polylysine, PLL-PEO20000, did not induce peptide demixing monitored by stabilization of the gramicidin channels, in contrast to parent polylysine (PLL). Both polymers were shown to bind effectively to negatively charged liposomes and lipid monolayers, suggesting that the ineffectiveness of PLL-PEO20000 was not due to reduction of its binding. It was hypothesized that PLL-PEO20000 could not induce domain formation due to steric hindrance of long PEO chains preventing lateral fusion of clusters. Another copolymer, PLL-PEO4000, having four PEO chains of 4000 Da, exhibited intermediate effect between PLL and PLL-PEO20000, which shows the importance of the copolymer architecture for the effect on the lateral distribution of OPg channels. The model system can be relevant to regulation of lateral organization of ion channels and other components in natural membrane systems.
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Affiliation(s)
- A A Pashkovskaya
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russian Federation
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12
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Peggion C, Coin I, Toniolo C. Total synthesis in solution of alamethicin F50/5 by an easily tunable segment condensation approach. Biopolymers 2005; 76:485-93. [PMID: 15499566 DOI: 10.1002/bip.20161] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A total synthesis in solution of the 19-mer peptide component F50/5 of alamethicin, the most extensively investigated among the channel-former peptaibol antibiotics, is reported. Three peptide segments (A, B, C) were prepared and assembled, followed by incorporation of the acetylated N-terminal amino acid. The synthetic modules B and C are characterized by three Glu(OMe) residues (at positions 7, 18, and 19) that, after completion of the synthesis, were reacted with ammonia to provide alamethicin F50/5. By use of this general strategy, we also prepared the [Gln7, Glu(OMe)18,19] alamethicin F50/5 analogue. The purity and conformation of the final products were assessed by chromatographic, spectrometric, and spectroscopic techniques. This tunable segment condensation approach will pave the way for an easy synthesis of alamethicin analogues bearing amino acid residues with desired side-chain probes even at the N-terminus and in internal positions of the sequence.
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Affiliation(s)
- Cristina Peggion
- Department of Chemistry, University of Padova, 35131 Padova, Italy
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Futaki S, Zhang Y, Kiwada T, Nakase I, Yagami T, Oiki S, Sugiura Y. Gramicidin-based channel systems for the detection of protein-ligand interaction. Bioorg Med Chem 2004; 12:1343-50. [PMID: 15018906 DOI: 10.1016/j.bmc.2003.06.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2003] [Revised: 06/04/2003] [Accepted: 06/05/2003] [Indexed: 10/26/2022]
Abstract
To detect protein-ligand interaction a gramicidin-based sensor was developed. Biotin was tagged to the C-terminus of gramicidin (Gram-bio 1). The biotin-moiety, which faces the electrolyte, gave little effect on single-channel conductance. Streptavidin added to the electrolyte was detected by Gram-bio 1 through the monitoring channel current using the planar bilayer system. The suppression of macroscopic currents and the acceleration of their decaying time course were observed in a concentration dependent manner. In the single-channel level, however, no significant effect on the single-channel conductance and the open dwell time was observed upon addition of streptavidin. Therefore, streptavidin neither blocked the open channel nor changed the stability of the conducting dimer. Insertion of a linker between gramicidin and biotin did not change the streptavidin-sensitivity of the current reduction. We conclude that the binding of streptavidin to the Gram-bio 1 shifted the distribution of the complex from the membrane to the electrolyte and, thus, reduced the formation of conducting dimer of Gram-bio 1 in the membrane. Interaction of biotin with an anti-biotin antibody was also observed using this system, indicating that this system is applicable for the detection of protein-ligand interaction having a binding constant of approximately 10(8-9) M(-1) or more. Both the adamantane-tagged gramicidin for detection of beta-cyclodextrin and the Strep Tag-II-tagged gramicidin for detection of streptavidin (binding constant: approximately 10(5) M(-1) or less) failed to respond. Thus, high-affinity ligands upon tagging to gramicidin render the gramicidin-based sensor able to execute as a real-time monitoring system for protein-ligand interaction.
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Affiliation(s)
- Shiroh Futaki
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
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14
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Jung G, Redemann T, Kroll K, Meder S, Hirsch A, Boheim G. Template-free self-assembling fullerene and lipopeptide conjugates of alamethicin form voltage-dependent ion channels of remarkable stability and activity. J Pept Sci 2004; 9:784-98. [PMID: 14658798 DOI: 10.1002/psc.525] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
N- and C-terminally modified with fullerene or lipopeptide alamethicin molecules were designed for the formation of template-free, self-assembling, voltage-dependent ion conducting channels. The automated solid phase synthesis of the alamethicin-F30 sequence was performed by in situ fluoride activation on 2-chlorotritylchloride-polystyrene resin and the conjugation with fullerenes-C60 and -C70 was carried out in solution. Voltage-dependent bilayer experiments revealed preferred channel sizes for C-terminal alamethicin F30-fullerene-C60 and -C70 conjugates and higher activity compared with native alamethicin, whereas N-terminally linked fullerene balls destabilize pore formation. C-terminal alamethicin F30-fullerene-C70 conjugates show pore states with remarkably long lifetimes of seconds. C-terminal lipopeptide conjugates of alamethicin were prepared by coupling via short peptide spacers with synthetic tripalmitoyl-S-glyceryl-cysteine. which represents the strong membrane anchoring N-terminus of bacterial lipoprotein. Alamethicin-lipopeptide conjugates exhibit high channel forming activities, whereby they self-assemble and adopt preferred pore states with extremely long lifetimes. The novel membrane modifying peptaibol constructs are valuable lead compounds for developments in sensorics related to transmembrane ion conductance.
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Affiliation(s)
- Günther Jung
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
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Kikukawa T, Araiso T. Changes in lipid mobility associated with alamethicin incorporation into membranes. Arch Biochem Biophys 2002; 405:214-22. [PMID: 12220535 DOI: 10.1016/s0003-9861(02)00396-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The binding state of the antibiotic peptide alamethicin with phospholipid bilayers was investigated in terms of the changes induced in lipid mobility. Fluorescence anisotropy was used for the study. It was found that an increase in peptide concentration induced different changes in lipid mobility above and below a critical peptide concentration. This concentration was also critical for an increase in the cooperative binding of the peptide, as detected by circular dichroism. Above the critical peptide concentration, the mobility of both lipid regions, around the polar head and hydrocarbon chain, became restricted with an increased peptide concentration. Below the critical level, however, an increased peptide concentration induced a "wobbling" of the lipid hydrocarbon chain. These results show that an increase in the cooperative binding of the peptide is accompanied by a change in the dominant configuration of the binding peptide. When the binding peptide increases, the dominant configuration appears to shift from surface association to deep incorporation within the membrane. This shift in configuration means that in the formation of ion-conductive pores, voltage-driven insertion of the peptide is a prominent step below a critical peptide concentration.
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Affiliation(s)
- Takashi Kikukawa
- Laboratory of Biomolecular Systems, Center for Advanced Science and Technology, Hokkaido University, Sappro 001-0021, Japan.
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Zhang Y, Futaki S, Kiwada T, Sugiura Y. Detection of protein-ligand interaction on the membranes using C-terminus biotin-tagged alamethicin. Bioorg Med Chem 2002; 10:2635-9. [PMID: 12057652 DOI: 10.1016/s0968-0896(02)00105-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
C-terminal biotin-tagged alamethicin, which has several alpha-aminoisobutyric acid (Aib) residues in its sequence, was synthesized by the preparation of the protected peptide segment using the 2-chlorotrityl resin, followed by conjugation with biotin hydrazide. Suppression of the channel current of the biotin-tagged alamethicin by the addition of streptavidin to the electrolyte was monitorable in real time using the planar lipid-bilayer method. The system was also applicable to the detection of interaction of the biotin-tagged alamethicin with the anti-biotin antibody.
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Affiliation(s)
- Y Zhang
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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17
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Shenkarev ZO, Balashova TA, Efremov RG, Yakimenko ZA, Ovchinnikova TV, Raap J, Arseniev AS. Spatial structure of zervamicin IIB bound to DPC micelles: implications for voltage-gating. Biophys J 2002; 82:762-71. [PMID: 11806918 PMCID: PMC1301885 DOI: 10.1016/s0006-3495(02)75438-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Zervamicin IIB is a 16-amino acid peptaibol that forms voltage-dependent ion channels with multilevel conductance states in planar lipid bilayers and vesicular systems. The spatial structure of zervamicin IIB bound to dodecylphosphocholine micelles was studied by nuclear magnetic resonance spectroscopy. The set of 20 structures obtained has a bent helical conformation with a mean backbone root mean square deviation value of approximately 0.2 A and resembles the structure in isotropic solvents (Balashova et al., 2000. NMR structure of the channel-former zervamicin IIB in isotropic solvents. FEBS Lett 466:333-336). The N-terminus represents an alpha-helix, whereas the C-terminal part has a mixed 3(10)/alpha(R) hydrogen-bond pattern. In the anisotropic micelle environment, the bending angle on Hyp10 (23 degrees) is smaller than that (47 degrees) in isotropic solvents. In the NOESY (Nuclear Overhauser Effect Spectroscopy) spectra, the characteristic attenuation of the peptide signals by 5- and 16-doxylstearate relaxation probes indicates a peripheral mode of the peptaibol binding to the micelle with the N-terminus immersed slightly deeper into micelle interior. Analysis of the surface hydrophobicity reveals that the zervamicin IIB helix is amphiphilic and well suited to formation of a tetrameric transmembrane bundle, according to the barrel-stave mechanism. The results are discussed in a context of voltage-driven peptaibol insertion into membrane.
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Affiliation(s)
- Z O Shenkarev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
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Futaki S, Fukuda M, Omote M, Yamauchi K, Yagami T, Niwa M, Sugiura Y. Alamethicin-leucine zipper hybrid peptide: a prototype for the design of artificial receptors and ion channels. J Am Chem Soc 2001; 123:12127-34. [PMID: 11734010 DOI: 10.1021/ja011166i] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this report, we describe a novel concept of extramembrane control of channel peptide assembly and the eventual channel current modulation. Alamethicin is a peptide antibiotic, which usually forms ion channels in various association states. By introducing an extramembrane leucine zipper segment (Alm-LeuZ), the association number of alamethicin was effectively controlled to produce a single predominant channel open state. The assembly was estimated to be a tetramer, by comparison of the channel conductance with that of the template-assembled Alm-LeuZ tetramer, which was prepared by the conjugation of a maleimide-functionalized peptide template with cysteine-derivatized Alm-LeuZ segments. Employment of an extramembrane segment of a random conformation provided higher levels of channel conductance. The result exemplified the possibility of channel current control by a conformational switch of the extramembrane segments.
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Affiliation(s)
- S Futaki
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
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19
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Goto C, Yamamura M, Satake A, Kobuke Y. Artificial ion channels showing rectified current behavior. J Am Chem Soc 2001; 123:12152-9. [PMID: 11734013 DOI: 10.1021/ja010761h] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Voltage-dependent artificial ion channels 3 and 4 were synthesized. Two cholic acid derivatives were connected through a m-xylylene dicarbamate unit at 3-hydroxyl groups. Asymmetries were introduced by terminal hydrophilic groups, carboxylic acid and phosphoric acid for 3 and hydroxyl and carboxylic acid for 4. Under basic conditions, these headgroups in 3 and 4 are expected to be dissociate into -1/-2 (pH 8.2) and 0/-1 (pH 7.2), respectively. Single ion channel properties were examined by a planar bilayer lipid membrane method under symmetrical 500 mM KCl at pH 8.2 or 7.2. When 3 and 4 were introduced into the bilayer membrane under application of positive voltage (a positive-shift method), the current values at positive applied voltage were larger than the corresponding ones at the negative applied voltage. The current-voltage plots were fitted by curves through a zero point to show clear rectification properties. The direction of rectification could be controlled by positive- or negative-shift methods. Vectorial alignment of terminal headgroup charges by the voltage-shift incorporation is essential for giving voltage-dependent rectified ion channels.
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Affiliation(s)
- C Goto
- CREST, Japan Science and Technology Corporation (JST), Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan
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20
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Futaki S, Youjun Z, Sugiura Y. Detecting a tag on a channel opening: blockage of the biotinylated channels by streptavidin. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(00)02287-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Bechinger B. The structure, dynamics and orientation of antimicrobial peptides in membranes by multidimensional solid-state NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1462:157-83. [PMID: 10590307 DOI: 10.1016/s0005-2736(99)00205-9] [Citation(s) in RCA: 368] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Linear peptide antibiotics have been isolated from amphibians, insects and humans and used as templates to design cheaper and more potent analogues for medical applications. Peptides such as cecropins or magainins are < or = 40 amino acids in length. Many of them have been prepared by solid-phase peptide synthesis with isotopic labels incorporated at selected sites. Structural analysis by solid-state NMR spectroscopy and other biophysical techniques indicates that these peptide antibiotics strongly interact with lipid membranes. In bilayer environments they exhibit amphipathic alpha-helical conformations and alignments of the helix axis parallel to the membrane surface. This contrasts the transmembrane orientations observed for alamethicin or gramicidin A. Models that have been proposed to explain the antibiotic and pore-forming activities of membrane-associated peptides, as well as other experimental results, include transmembrane helical bundles, wormholes, carpets, detergent-like effects or the in-plane diffusion of peptide-induced bilayer instabilities.
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Affiliation(s)
- B Bechinger
- Max Planck Institute for Biochemistry, Am Klopferspitz 18A, 82152, Martinsried, Germany.
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22
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Kropacheva TN, Raap J. Voltage-dependent interaction of the peptaibol antibiotic zervamicin II with phospholipid vesicles. FEBS Lett 1999; 460:500-4. [PMID: 10556525 DOI: 10.1016/s0014-5793(99)01401-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The effect of a transmembrane potential on ion channel formation by zervamicin II (ZER-II) was studied in a vesicular model system. The dissipation of diffusion potential caused by addition of ZER-II to small phosphatidylcholine vesicles was monitored using fluorescent (Safranine T) and optical (Oxonol YI) probes. Cis-positive potentials facilitated channel formation, while at cis-negative potentials, ion fluxes were inhibited. A potential-independent behavior of ZER-II was observed at high peptide concentrations, most likely due to its membrane modifying property.
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Affiliation(s)
- T N Kropacheva
- Chemistry Department, Udmurt State University, Izhevsk, Russia
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23
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Snook CF, Woolley GA, Oliva G, Pattabhi V, Wood SF, Blundell TL, Wallace BA. The structure and function of antiamoebin I, a proline-rich membrane-active polypeptide. Structure 1998; 6:783-92. [PMID: 9655831 DOI: 10.1016/s0969-2126(98)00079-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Antiamoebin is a member of the peptaibol family of polypeptides and has a unique antibiotic activity: it acts as an antiamoebic agent, but does not effectively haemolyze erythrocytes even though it does exhibit membrane-modifying activity. RESULTS The structure of antiamoebin I has been determined by X-ray crystallography at 1.4 A resolution. The molecule forms a helical structure, which, as a result of the presence of a number of proline and hydroxyproline residues, has a deep bend in the middle. Circular dichroism spectroscopy, single-channel conductance studies and fluorescence diffusion studies suggest a mode of ion transport that is entirely different from that of the other two members of the peptaibol family (alamethicin and zervamicin) whose structures and functions have been examined in detail. CONCLUSIONS The structure of the polypeptide has been determined and a functional model for its mode of action in membranes is presented. Although under some conditions antiamoebin may form ion channels, unlike the closely related alamethicin and zervamicin polypeptides, its major membrane-modifying activity appears to be as an ion carrier.
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Affiliation(s)
- C F Snook
- Department of Crystallography Birkbeck College University of London London, WC1E 7HX, UK
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24
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Fyles TM, Loock D, Zhou X. A Voltage-Gated Ion Channel Based on a Bis-Macrocyclic Bolaamphiphile. J Am Chem Soc 1998. [DOI: 10.1021/ja972648q] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- T. M. Fyles
- Contribution from the Department of Chemistry, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - D. Loock
- Contribution from the Department of Chemistry, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - X. Zhou
- Contribution from the Department of Chemistry, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
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25
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Helluin O, Dugast JY, Molle G, Mackie AR, Ladha S, Duclohier H. Lateral diffusion and conductance properties of a fluorescein-labelled alamethicin in planar lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1330:284-92. [PMID: 9408182 DOI: 10.1016/s0005-2736(97)00139-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In order to follow alamethicin diffusion within membranes under conditions of pore-formation, a fluorescein isothiocyanate (FITC) analogue was synthesized. To test the influence of the fluorescent probe addition on the pore-forming activity of the new analogue, macroscopic and single-channel experiments into planar lipid bilayers were performed. Although the apparent mean number of monomers per conducting aggregate was equivalent, the voltage-dependence of the new analogue was slightly reduced and hysteresses were broader, in agreement with the much longer duration of the open single-channels. Thus, the conducting aggregates seem to be stabilized by the introduction of the probe, presumably through the interaction of the conjugated cycles with the lipid headgroups, while the added steric hindrance may account for the slightly higher conductances of the open substates. Lateral diffusion of the labelled peptide associated with the bilayer was then investigated by the fluorescence recovery after photobleaching technique. Under applied voltage, associated with high conductance, D, the lateral diffusion coefficient, was reduced by 50% when compared to peptide at rest. These results provide new independent experimental evidence for a voltage-driven insertion of the highly mobile surface-associated peptide into the bilayer as a prominent step in pore formation.
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Affiliation(s)
- O Helluin
- UMR 6522 CNRS-Université de Rouen (IFRMP 23), Mont Saint Aignan, France
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26
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Woolley GA, Biggin PC, Schultz A, Lien L, Jaikaran DC, Breed J, Crowhurst K, Sansom MS. Intrinsic rectification of ion flux in alamethicin channels: studies with an alamethicin dimer. Biophys J 1997; 73:770-8. [PMID: 9251793 PMCID: PMC1180973 DOI: 10.1016/s0006-3495(97)78109-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Covalent dimers of alamethicin form conducting structures with gating properties that permit measurement of current-voltage (I-V) relationships during the lifetime of a single channel. These I-V curves demonstrate that the alamethicin channel is a rectifier that passes current preferentially, with voltages of the same sign as that of the voltage that induced opening of the channel. The degree of rectification depends on the salt concentration; single-channel I-V relationships become almost linear in 3 M potassium chloride. These properties may be qualitatively understood by using Poisson-Nernst-Planck theory and a modeled structure of the alamethicin pore.
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Affiliation(s)
- G A Woolley
- Department of Chemistry, University of Toronto, Canada.
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27
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Toniolo C, Polese A, Formaggio F, Crisma M, Kamphuis J. Circular Dichroism Spectrum of a Peptide 310-Helix. J Am Chem Soc 1996. [DOI: 10.1021/ja9537383] [Citation(s) in RCA: 326] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Claudio Toniolo
- Biopolymer Research Center, CNR Department of Organic Chemistry University of Padova, 35131 Padova, Italy DSM Research, Bio-organic Chemistry Section 6160 MD Geleen, The Netherlands
| | - Alessandra Polese
- Biopolymer Research Center, CNR Department of Organic Chemistry University of Padova, 35131 Padova, Italy DSM Research, Bio-organic Chemistry Section 6160 MD Geleen, The Netherlands
| | - Fernando Formaggio
- Biopolymer Research Center, CNR Department of Organic Chemistry University of Padova, 35131 Padova, Italy DSM Research, Bio-organic Chemistry Section 6160 MD Geleen, The Netherlands
| | - Marco Crisma
- Biopolymer Research Center, CNR Department of Organic Chemistry University of Padova, 35131 Padova, Italy DSM Research, Bio-organic Chemistry Section 6160 MD Geleen, The Netherlands
| | - Johan Kamphuis
- Biopolymer Research Center, CNR Department of Organic Chemistry University of Padova, 35131 Padova, Italy DSM Research, Bio-organic Chemistry Section 6160 MD Geleen, The Netherlands
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28
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Heimburg T, Biltonen RL. A Monte Carlo simulation study of protein-induced heat capacity changes and lipid-induced protein clustering. Biophys J 1996; 70:84-96. [PMID: 8770189 PMCID: PMC1224911 DOI: 10.1016/s0006-3495(96)79551-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Monte Carlo simulations were used to describe the interaction of peripheral and integral proteins with lipids in terms of heat capacity profiles and protein distribution. The simulations were based on a two-state model for the lipid, representing the lipid state as being either gel or fluid. The interaction between neighboring lipids has been taken into account through an unlike nearest neighbor free energy term delta omega, which is a measure of the cooperativity of the lipid transition. Lipid/protein interaction was considered using the experimental observation that the transition midpoints of lipid membranes are shifted upon protein binding, a thermodynamic consequence of different binding constants of protein with fluid or gel lipids. The difference of the binding free energies was used as an additional parameter to describe lipid-protein interaction. The heat capacity profiles of lipid/protein complexes could be well described for both peripheral and integral proteins. Binding of proteins results in a shift and an asymmetric broadening of the melting profile. The model results in a coexistence of gel and fluid lipid domains in the proximity of the thermotropic transition. As a consequence, bound peripheral proteins aggregate in the temperature range of the lipid transition. Integral proteins induce calorimetric melting curves that are qualitatively different from that of peripheral proteins and aggregate in either gel or liquid crystalline lipid phase. The results presented here are in good agreement with calorimetric experiments on lipid-protein complexes and have implementations for the functional control of proteins.
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Affiliation(s)
- T Heimburg
- Max-Planck-Institut für biophysikalische Chemie, Gottingen-Nikolausberg, Germany.
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29
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Kerr ID, Dufourcq J, Rice JA, Fredkin DR, Sansom MS. Ion channel formation by synthetic analogues of staphylococcal delta-toxin. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1236:219-27. [PMID: 7540870 DOI: 10.1016/0005-2736(95)00051-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Ion channel formation by three analogues of staphylococcal delta-toxin, an amphipathic and alpha-helical channel-forming peptide, has been evaluated by measurement of ionic currents across planar lipid bilayers. Replacement of beta-branched, hydrophobic residues by leucine and movement of a tryptophan residue from the hydrophilic to the hydrophobic face of the helix does not significantly alter ion channel activity. Removal of the N-terminal blocking group combined with the substitution of glycine-10 by leucine changes the single channel properties of delta-toxin, without altering macroscopic conductance/voltage behaviour. Truncation of the N-terminus by three residues results in complete loss of channel-forming activity. These changes in channel-forming properties upon altering the peptide sequence do not mirror changes in haemolytic activity. The results lend support to the proposal that channel formation and haemolysis are distinct events. Channel properties are discussed in the context of a model in which the pore is formed by a bundle of approximately parallel transbilayer helices.
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Affiliation(s)
- I D Kerr
- Centre de Récherche Paul Pascal, CNRS, Pessac, France
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