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Matsuki H, Goto M, Motohashi M, Kiguchi A, Nakao T, Tamai N. Formation of intermediate gel-liquid crystalline phase on medium-chain phosphatidylcholine bilayers: Phase transitions depending on the bilayer packing. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183197. [PMID: 31958435 DOI: 10.1016/j.bbamem.2020.183197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/27/2019] [Accepted: 01/15/2020] [Indexed: 11/28/2022]
Abstract
The bilayer phase transitions of medium-chain phosphatidylcholines with linear saturated acyl chains (Cn = 12, 13 and 14) were measured by high-pressure light-transmittance measurements and differential scanning calorimetry to investigate the formation of intermediate gel-liquid crystalline phase called Lx phase. The constructed phase diagrams showed that there existed a distinct region of the Lx phase between ripple gel (Pβ') and liquid crystalline (Lα) phase for multilamellar vesicle bilayers of C12PC and C13PC. The Lx phase of the C12PC bilayer was metastable at all pressures and disappeared at a higher pressure. In the C13PC bilayer, the Lx phase was stable and also disappeared at a higher pressure but its region markedly shrunk. By contrast, the Lx phase was not detected for the C14PC bilayer. Effects of other factors such as vesicle size and solvent substitution on the Lx phase of the C13PC bilayer were also examined. A decrease in vesicle size and solvent substitution from water to 50 wt% ethylene glycol solution promoted the Lx-phase formation as opposed to the effects of acyl-chain elongation and pressurization. The fluorescence data of the C13PC bilayer with different vesicle sizes showed that the Lx phase is caused by the difference of local packing in the bilayer. Considering these facts, we concluded that the Lx phase is an intermediate gel-Lα phase that has gel-phase monolayers with negative curvature and Lα-phase monolayers with positive curvature. The formation mechanism of the Lx-phase in stacked bilayers and dispersed vesicles is also explainable by this difference in packing state.
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Affiliation(s)
- Hitoshi Matsuki
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8513, Japan.
| | - Masaki Goto
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8513, Japan
| | - Makiko Motohashi
- Department of Biological Science and Technology, Faculty of Engineering, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Aoi Kiguchi
- Department of Biological Science and Technology, Faculty of Engineering, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Toshiki Nakao
- Department of Biological Science and Technology, Faculty of Engineering, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Nobutake Tamai
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8513, Japan
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Purushothaman S, Cicuta P, Ces O, Brooks NJ. Influence of High Pressure on the Bending Rigidity of Model Membranes. J Phys Chem B 2015; 119:9805-10. [DOI: 10.1021/acs.jpcb.5b05272] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Sowmya Purushothaman
- Department
of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - Pietro Cicuta
- Cavendish
Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K
| | - Oscar Ces
- Department
of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - Nicholas J. Brooks
- Department
of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
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3
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Recent Progress in Density Functional Methodology for Biomolecular Modeling. STRUCTURE AND BONDING 2013. [DOI: 10.1007/978-3-642-32750-6_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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4
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Pius J, Morrow MR, Booth V. 2H Solid-State Nuclear Magnetic Resonance Investigation of Whole Escherichia coli Interacting with Antimicrobial Peptide MSI-78. Biochemistry 2011; 51:118-25. [DOI: 10.1021/bi201569t] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- James Pius
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s,
NL, Canada A1B 3X9
| | - Michael R. Morrow
- Department
of Physics and Physical
Oceanography, Memorial University of Newfoundland, St. John’s, NL, Canada A1B 3X7
| | - Valerie Booth
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s,
NL, Canada A1B 3X9
- Department
of Physics and Physical
Oceanography, Memorial University of Newfoundland, St. John’s, NL, Canada A1B 3X7
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5
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Thermotropic and barotropic phase transitions of dilauroylphosphatidylcholine bilayer. Chem Phys Lipids 2008; 153:138-43. [DOI: 10.1016/j.chemphyslip.2008.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 02/15/2008] [Accepted: 03/03/2008] [Indexed: 11/17/2022]
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6
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Skanes ID, Stewart J, Keough KMW, Morrow MR. Effect of chain unsaturation on bilayer response to pressure. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:051913. [PMID: 17279945 DOI: 10.1103/physreve.74.051913] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Indexed: 05/13/2023]
Abstract
Using wide-line deuterium NMR, the effects of pressure on saturated-chain orientational order and gel-to-liquid-crystal phase transition temperature were observed in bilayers of 16:0-18:1 PC-d31 (POPC-d31) and 16:0-18:2 PC-d31 (PLPC-d31). Spectra were recorded for a range of pressures at selected temperatures and for a range of temperatures at selected pressures up to 193 MPa. For 16:0-18:1 PC-d31, the main transition temperature increased by approximately 0.18 K/MPa, a rate that is similar to what is found for bilayers of disaturated PC's. For 16:0-18:2 PC-d31, the increase in transition temperature with pressure was slightly smaller at approximately 0.13 K/MPa. To investigate the isothermal response of chain orientational order to pressure, spectra for each lipid were obtained for three pressures (ambient, 55 MPa, and 110 MPa) near room temperature (approximately 25 degrees C) and for three pressures (ambient, 110 MPa, and 193 MPa) at higher temperature (approximately 40 degrees C). These temperatures were chosen such that the difference between the higher observation temperature and the main transition of 16:0-18:1 PC-d31 would be similar to the difference between the lower observation temperature and the main transition of 16:0-18:2 PC-d31. Application of a given pressure was found to raise the orientational order for all methylene groups on the saturated chain of a particular lipid by roughly similar amounts. For comparable pressure differences, the pressure-induced ordering of the 16:0-18:1 PC-d31 saturated chain at approximately 40 degrees C was greater than that of the corresponding chain in 16:0-18:2 PC- d31 at approximately 25 degrees C. These observations suggest that increasing levels of chain unsaturation may reduce the sensitivity of bilayer order to variations in pressure at corresponding temperatures relative to their ambient pressure transitions.
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Affiliation(s)
- I D Skanes
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X7, Canada
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7
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Harroun TA, Nieh MP, Watson MJ, Raghunathan VA, Pabst G, Morrow MR, Katsaras J. Relationship between the unbinding and main transition temperatures of phospholipid bilayers under pressure. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:031906. [PMID: 15089321 DOI: 10.1103/physreve.69.031906] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Indexed: 05/24/2023]
Abstract
Using neutron diffraction and a specially constructed high pressure cell suitable for aligned multibilayer systems, we have studied, as a function of pressure, the much observed anomalous swelling regime in dimyristoyl- and dilauroyl-phosphatidylcholine bilayers, DMPC and DLPC, respectively. We have also reanalyzed data from a number of previously published experiments and have arrived at the following conclusions. (a). The power law behavior describing anomalous swelling is preserved in all PC bilayers up to a hydrostatic pressure of 240 MPa. (b). As a function of increasing pressure there is a concomitant decrease in the anomalous swelling of DMPC bilayers. (c). For PC lipids with hydrocarbon chains >or=13 carbons the theoretical unbinding transition temperature T small star, filled is coupled to the main gel-to-liquid crystalline transition temperature T(M). (d). DLPC is intrinsically different from the other lipids studied in that its T small star, filled is not coupled to T(M). (e). For DLPC bilayers we predict a hydrostatic pressure (>290 MPa) where unbinding may occur.
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Affiliation(s)
- T A Harroun
- National Research Council, Steacie Institute for Molecular Sciences, Chalk River, Ontario, Canada K0J 1J0
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8
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Brown A, Skanes I, Morrow MR. Pressure-induced ordering in mixed-lipid bilayers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2004; 69:011913. [PMID: 14995653 DOI: 10.1103/physreve.69.011913] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Indexed: 05/24/2023]
Abstract
Isothermal application of hydrostatic pressure to liquid crystalline phospholipid bilayers increases chain segment orientational order and thus chain extension. By using pressure to perturb chain order in single-component bilayers and bilayers comprising a binary mixture of lipids, it is possible to compare the relative influences of intrinsic lipid properties and collective bilayer properties on chain orientational order. Deuterium nuclear magnetic resonance was used to investigate the response of saturated chain orientational order to pressure in single-component and two-component liquid crystal bilayers of lipids having saturated chains of different lengths (dipalmitoyl phosphatidylcholine and dimyristoyl phosphatidylcholine) or having one saturated chain and one unsaturated chain (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine). For bilayers containing a single lipid species, the isothermal response of average chain orientational order to pressure decreased with increasing difference between measurement temperature and that lipid's ambient-pressure gel-to-liquid-crystalline phase transition temperature. For all of the lipids observed, the range of orientational order displayed by the saturated chain methylene groups was approximately conserved as pressure was applied. In binary mixtures, the difference between the average saturated chain orientational orders of the two bilayer components was approximately conserved as pressure was increased. These observations provide some insight into how the response of the bilayer to pressure is distributed over interacting components with different intrinsic properties and illustrate the sensitivity of the effective chain ordering potential in the bilayer interior to bilayer composition.
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Affiliation(s)
- Andre Brown
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3X7
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9
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Bonev BB, Lam YH, Anderluh G, Watts A, Norton RS, Separovic F. Effects of the eukaryotic pore-forming cytolysin Equinatoxin II on lipid membranes and the role of sphingomyelin. Biophys J 2003; 84:2382-92. [PMID: 12668447 PMCID: PMC1302805 DOI: 10.1016/s0006-3495(03)75044-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Equinatoxin II (EqtII), a protein toxin from the sea anemone Actinia equina, readily creates pores in sphingomyelin-containing lipid membranes. The perturbation by EqtII of model lipid membranes composed of dimyristoylphosphatidycholine and sphingomyelin (10 mol %) was investigated using wideline phosphorus-31 and deuterium NMR. The preferential interaction between EqtII (0.1 and 0.4 mol %) and the individual bilayer lipids was studied by (31)P magic angle spinning NMR, and toxin-induced changes in bilayer morphology were examined by freeze-fracture electron microscopy. Both NMR and EM showed the formation of an additional lipid phase in sphingomyelin-containing mixed lipid multilamellar suspensions with 0.4 mol % EqtII. The new toxin-induced phase consisted of small unilamellar vesicles 20-40 nm in diameter. Deuterium NMR showed that the new lipid phase contains both dimyristoylphosphatidycholine and sphingomyelin. Solid-state (31)P NMR showed an increase in spin-lattice and a decrease in spin-spin relaxation times in mixed-lipid model membranes in the presence of EqtII, consistent with an increase in the intensity of low frequency motions. The (2)H and (31)P spectral intensity distributions confirmed a change in lipid mobility and showed the creation of an isotropic lipid phase, which was identified as the small vesicle structures visible by electron microscopy in the EqtII-lipid suspensions. The toxin appears to enhance slow motions in the membrane lipids and destabilize the membrane. This effect was greatly enhanced in sphingomyelin-containing mixed lipid membranes compared with pure phosphatidylcholine bilayers, suggesting a preferential interaction between the toxin and bilayer sphingomyelin.
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Affiliation(s)
- Boyan B Bonev
- Biomembrane Structure Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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10
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Uhríková D, Rapp G, Balgavý P. Condensed lamellar phase in ternary DNA-DLPC-cationic gemini surfactant system: a small-angle synchrotron X-ray diffraction study. Bioelectrochemistry 2002; 58:87-95. [PMID: 12401574 DOI: 10.1016/s1567-5394(02)00122-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We report on a small-angle synchrotron X-ray diffraction study of dilauroylphosphatidylcholine (DLPC) liposomes aggregated with high molecular DNA in the presence of 1,4-butanediammonium-N,N'-dilauryl-N,N,N',N'-tetramethyl gemini surfactant cations (C12GS). The aggregates prepared at the DLPC/C12GS/DNA phosphate group=2:1:1.6 molar ratio in 0.0015 mol x l(-1) NaCl aqueous solution exhibit Bragg reflections due to lamellar lipid bilayer stacking and the Bragg reflection typical of one-dimensional DNA lattice with parallel strands intercalated between lipid bilayers. In this condensed fluid lamellar L(alpha)(c) phase, the interactions between DNA and charged bilayers damp the thermally induced bilayer undulations. The diffraction data obtained with the mixture of DLPC liposomes and DNA (at DNA phosphate group/DLPC=0.8:1 molar ratio) indicate a DNA-lipid interaction in the absence of C12GS.
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Affiliation(s)
- Daniela Uhríková
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, J A Comenius University, Odbojárov 10, SK-832 32, Bratislava, Slovak Republic
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11
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Kornblatt JA, Kornblatt MJ. The effects of osmotic and hydrostatic pressures on macromolecular systems. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1595:30-47. [PMID: 11983385 DOI: 10.1016/s0167-4838(01)00333-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Osmotic pressure and hydrostatic pressure can be used effectively to probe the behavior of biologically important macromolecules and their complexes. Using the two techniques requires a theoretical framework as well as knowledge of the more common pitfalls. Both are discussed in this review in the context of several examples.
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Affiliation(s)
- Jack A Kornblatt
- Enzyme Research Group, Department of Biology, Concordia University, Montreal, QC, Canada.
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12
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Liao C, Chen SH. Theory of the generalized dynamic structure factor of polyatomic molecular fluids measured by inelastic x-ray scattering. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 64:021205. [PMID: 11497570 DOI: 10.1103/physreve.64.021205] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2000] [Indexed: 05/23/2023]
Abstract
We describe a theory for the calculation of the generalized dynamic structure factor S(k,omega) as measured by an inelastic x-ray scattering (IXS) experiment on single-component molecular or polyatomic molecular fluids. IXS spectrum of a simple fluid is proportional to the dynamic structure factor of a single species of atom. In the case of a molecular fluid, however, IXS spectrum is a weighted sum of partial dynamic structure factors of pairs of atomic species. The weighting factors are products of the atomic form factors of the pairs. We call this weighted average dynamic structure factor the generalized dynamic structure factor. We extend the formalism of a three effective eigenmode theory (TEE) developed previously for simple fluids to derive an approximate evolution equation for the generalized dynamic structure factor, which can be considered as a generalized hydrodynamic equation for molecular fluids. As examples, we first study the contributions of the partial dynamic structure factor to the generalized dynamic structure factor computed from molecular dynamics simulation of SPC/E model water. We found that the generalized dynamic structure factor of water measured by IXS can be well approximated by the center of mass or the oxygen atom dynamic structure factors. The generalized TEE model was then employed to analyze IXS spectra of nearly fully hydrated dilauroylphosphatidylcholine. The theory is able to fit all of the spectra in the k range from 5 to 32 nm(-1) quantitatively and gives their deconvoluted generalized dynamic structure factors.
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Affiliation(s)
- C Liao
- Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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13
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Peltonen L, Hirvonen J, Yliruusi J. The Effect of Temperature on Sorbitan Surfactant Monolayers. J Colloid Interface Sci 2001; 239:134-138. [PMID: 11397057 DOI: 10.1006/jcis.2001.7520] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of temperature on four sorbitan ester (Span 20, sorbitan monolaurate; Span 40, sorbitan monopalmitate; Span 60, sorbitan monostearate; and Span 80, sorbitan monooleate) monolayers was analyzed. The covered temperature range was from 22 to 42 degrees C. Surface pressure-molecular area isotherms were measured with a Langmuir-type instrument. As the temperature was increased, the monolayers expanded more. This change can also be seen from the surface compressional modulus that was lowered as the temperature was increased. Also, the collapse pressure was lowered as the temperature was increased. Copyright 2001 Academic Press.
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Affiliation(s)
- Leena Peltonen
- Department of Pharmacy, Pharmaceutical Technology Division, University of Helsinki, Helsinki, FIN-00014, Finland
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Chicano JJ, Ortiz A, Teruel JA, Aranda FJ. Organotin compounds alter the physical organization of phosphatidylcholine membranes. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1510:330-41. [PMID: 11342170 DOI: 10.1016/s0005-2736(00)00365-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Organotin compounds have a broad range of biological activities and are ubiquitous contaminants in the environment. Their toxicity mainly lies in their action on the membrane. In this contribution we study the interaction of tributyltin and triphenyltin with model membranes composed of phosphatidylcholines of different acyl chain lengths using differential scanning calorimetry, (31)P-nuclear magnetic resonance, X-ray diffraction and infrared spectroscopy. Organotin compounds broaden the main gel to liquid-crystalline phase transition, shift the transition temperature to lower values and induce the appearance of a new peak below the main transition peak. These effects are more pronounced in the case of tributyltin and are quantitatively larger as the phosphatidylcholine acyl chain length decreases. Both tributyltin and triphenyltin increase the enthalpy change of the transition in all the phosphatidylcholine systems studied except in dilauroylphosphatidylcholine. Organotin compounds do not affect the macroscopic bilayer organization of the phospholipid but do affect the degree of hydration of its carbonyl moiety. The above evidence supports the idea that organotin compounds are located in the upper part of the phospholipid palisade near the lipid/water interface.
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Affiliation(s)
- J J Chicano
- Departamento de Bioquímica y Biología Molecular A, Facultad de Veterinaria, Universidad de Murcia, Campus de Espinardo, E-30100, Murcia, Spain
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15
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Chen SH, Liao CY, Huang HW, Weiss TM, Bellisent-Funel MC, Sette F. Collective dynamics in fully hydrated phospholipid bilayers studied by inelastic x-ray scattering. PHYSICAL REVIEW LETTERS 2001; 86:740-743. [PMID: 11177926 DOI: 10.1103/physrevlett.86.740] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2000] [Indexed: 05/23/2023]
Abstract
The short wavelength density fluctuation of DLPC (dilaurylphosphatidylcholine) bilayers close to full hydration has been studied by the inelastic x-ray scattering technique below and above the main transition temperature. The analysis based on a generalized three effective eigenmode theory allows us to construct the dispersion relation of the high frequency sound mode for the first time. The marked softening of the excitation near k = 14 nm(-1), corresponding to the lipid chain-chain correlation peak in the structure factor, in the L(alpha) phase implies prevalent occurrences of short-wavelength in-plane motions of lipid chains that might be of importance for transportation of small molecules across membranes.
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Affiliation(s)
- S H Chen
- Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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16
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Milhaud J, Michels B. Binding of nystatin and amphotericin B with sterol-free L-dilauroylphosphatidylcholine bilayers resulting in the formation of dichroic lipid superstructures. Chem Phys Lipids 1999; 101:223-35. [PMID: 10533264 DOI: 10.1016/s0009-3084(99)00062-6] [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: 11/19/2022]
Abstract
Interactions of multilamellar vesicles (MLV) of dilauroylphosphatidylcholine (DLPC) with the polyene antibiotics, amphotericin B (AmB) and nystatin (Ny), were followed by circular dichroism (CD). These interactions proceed with both antibiotics through a slow association with high [DLPC]/[antibiotic] stoichiometric molar ratios (> or = 130), at room temperature for which DLPC membranes are in a fluid state. Microscopic investigations of the spatial distributions of the antibiotic and the MLV in the mixtures revealed that MLV form clusters inside which the antibiotic is strongly concentrated and lipid superstructures appear. Concomitantly with the appearance of these superstructures a DLPC dichroic signal emerges. This observation indicates that the chiral properties of antibiotic oligomers can induce a chirality of the DLPC molecules which are bound to them. These results support the hypothesis of a recent molecular modeling of AmB oligomers which postulates that their chiral properties result from a chiral assemblage of antibiotic molecules (Millié et al., J. Phys. Chem. B, in press).
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Affiliation(s)
- J Milhaud
- Laboratoire de Physicochimie Biomoleculaire et cellulaire (ESA 7033), Université Paris VI, France
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17
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de Planque MR, Greathouse DV, Koeppe RE, Schäfer H, Marsh D, Killian JA. Influence of lipid/peptide hydrophobic mismatch on the thickness of diacylphosphatidylcholine bilayers. A 2H NMR and ESR study using designed transmembrane alpha-helical peptides and gramicidin A. Biochemistry 1998; 37:9333-45. [PMID: 9649314 DOI: 10.1021/bi980233r] [Citation(s) in RCA: 206] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We have investigated the effect of a series of hydrophobic polypeptides (WALP peptides) on the mean hydrophobic thickness of (chain-perdeuterated) phosphatidylcholines (PCs) with different acyl chain length, using 2H NMR and ESR techniques. The WALP peptides are uncharged and consist of a sequence with variable length of alternating leucine and alanine, flanked on both sides by two tryptophans, and with the N- and C-termini blocked, e.g., FmAW2(LA)nW2AEtn. 2H NMR measurements showed that the shortest peptide with a total length of 16 amino acids (WALP16) causes an increase of 0.6 A in bilayer thickness in di-C12-PC, a smaller increase in di-C14-PC, no effect in di-C16-PC, and a decrease of 0.4 A in di-C18-PC, which was the largest decrease observed in any of the peptide/lipid systems. The longest peptide, WALP19, in di-C12-PC caused the largest increase in thickness of the series (+1.4 A), which decreased again for longer lipids toward di-C18-PC, in which no effect was noticed. WALP17 displayed an influence intermediate between that of WALP16 and WALP19. Altogether, incorporation of the WALP peptides was found to result in small but very systematic changes in bilayer thickness and area per lipid molecule, depending on the difference in hydrophobic length between the peptide and the lipid bilayer in the liquid-crystalline phase. ESR measurements with spin-labeled lipid probes confirmed this result. Because thickness is expected to be influenced most at the lipids directly adjacent to the peptides, also the maximal adaptation of these first-shell lipids was estimated. The calculation was based on the assumption that there is little or no aggregation of the WALP peptides, as was supported by ESR, and that lipid exchange is rapid on the 2H NMR time scale. It was found that even the maximal possible changes in first-shell lipid length were relatively small and represented only a partial response to mismatch. The synthetic WALP peptides are structurally related to the gramicidin channel, which was therefore used for comparison. In most lipid systems, gramicidin proved to be a stronger perturber of bilayer thickness than WALP19, although its length should approximate that of the shorter WALP16. The effects of gramicidin and WALP peptides on bilayer thickness were evaluated with respect to previous 31P NMR studies on the effects of these peptides on macroscopic lipid phase behavior. Both approaches indicate that, in addition to the effective hydrophobic length, also the physical nature of the peptide surface is a modulator of lipid order.
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Affiliation(s)
- M R de Planque
- Department Biochemistry of Membranes, Center for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, The Netherlands.
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18
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Tristram-Nagle S, Moore T, Petrache HI, Nagle JF. DMSO produces a new subgel phase in DPPC: DSC and X-ray diffraction study. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1369:19-33. [PMID: 9528670 DOI: 10.1016/s0005-2736(97)00197-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Equilibrium phases and the kinetics of subgel phase transformation of dipalmitoylphosphatidylcholine (DPPC) hydrated with mixtures of dimethylsulfoxide (DMSO)/water have been studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The rate of gel-to-subgel transformation is decreased with a small increase in X, the DMSO/water mole fraction, but then speeds up and becomes faster than in pure water by X = 0.16. The DSC scans show multiple subgel peaks, some of which can be attributed to impacted domain growth. For X greater than 0.10, XRD shows that there is a new, stable subgel phase, S, which also accounts for some of the multiplicity of DSC peaks. Our electron density profiles show that the thickness of the bilayer in the S phase is greater than in the usual C subgel phase. We suggest that the S subgel phase is characterized by different headgroup ordering and smaller chain tilt angle than in the C subgel phase. Electron density profiles show that increasing X decreases the water space between bilayers in all phases, subgel, gel and fluid (L alpha). For X = 0.20, a different gel phase is also observed that may be due to subtle changes in the orientation of chain tilt first observed in partially dehydrated DMPC. The dehydrating effect of DMSO explains the results of a previous study, confirmed in this study, that increasing the concentration of DMSO raises the main transition temperature and eliminates the ripple phase.
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Affiliation(s)
- S Tristram-Nagle
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA. stn+@andrew.cmu.edu
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Milhaud J, Berrehar J, Lancelin JM, Michels B, Raffard G, Dufourc EJ. Association of polyene antibiotics with sterol-free lipid membranes. II. Hydrophobic binding of nystatin to dilauroylphosphatidylcholine bilayers. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1326:54-66. [PMID: 9188800 DOI: 10.1016/s0005-2736(97)00008-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Interaction of nystatin A1 with multilamellar vesicles (MLV) of dilauroylphosphatidylcholine (DLPC), observed either by adding nystatin to preformed MLV (mixtures I) or by incorporating it during the formation of vesicles (mixtures II, inner lamellas of MLV in contact with nystatin) was investigated for 0.002 < or = nystatin/DLPC = R(A) < or = 0.20, by four complementary methods. The main results were: (i) Ultraviolet absorption and circular dichroism (CD) spectra of mixtures I revealed the occurrence of a saturable association with a stoichiometry (R(A) = 0.007 +/- 0.002) constant between 3 and 33 degrees C. (ii) By differential scanning calorimetry, thermograms of the two types of mixtures were similar only when water was in great excess. In the opposite (e.g., (H2O)/(DLPC) = R(W) < or = 300), mixture II thermograms displayed two features, upshifted by about 6.5 degrees C with respect to the sharp peak observed with mixture I, resembling those obtained for pure DLPC when the low-temperature phase was the subgel phase. For this R(W), the nystatin absolute concentrations were those for which nystatin form superaggregates as revealed by the nystatin CD spectra. It is proposed that these superaggregates are excluded from the interlamellar spacings of MLV and exert a pumping action on the interlamellar water. The subsequent dehydration of the inner lamellas is thought to convert them into the subgel state. (iii) 2H-NMR spectra of sn-2-perdeuterated DLPC MLV + nystatin mixtures II, confirmed such a temperature shift of the main transition. They showed, in addition, an ordering of the aliphatic chains immediately above the transition temperature, equivalent to a bilayer thickening of 2 A.
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Affiliation(s)
- J Milhaud
- Laboratoire de Physicochimie biomoléculaire et cellulaire (UA CNRS 2056), Université Paris VI, France
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