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Rózsa ZB, Hantal G, Szőri M, Fábián B, Jedlovszky P. Understanding the Molecular Mechanism of Anesthesia: Effect of General Anesthetics and Structurally Similar Non-Anesthetics on the Properties of Lipid Membranes. J Phys Chem B 2023. [PMID: 37368412 DOI: 10.1021/acs.jpcb.3c02976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
General anesthesia can be caused by various, chemically very different molecules, while several other molecules, many of which are structurally rather similar to them, do not exhibit anesthetic effects at all. To understand the origin of this difference and shed some light on the molecular mechanism of general anesthesia, we report here molecular dynamics simulations of the neat dipalmitoylphosphatidylcholine (DPPC) membrane as well as DPPC membranes containing the anesthetics diethyl ether and chloroform and the structurally similar non-anesthetics n-pentane and carbon tetrachloride, respectively. To also account for the pressure reversal of anesthesia, these simulations are performed both at 1 bar and at 600 bar. Our results indicate that all solutes considered prefer to stay both in the middle of the membrane and close to the boundary of the hydrocarbon domain, at the vicinity of the crowded region of the polar headgroups. However, this latter preference is considerably stronger for the (weakly polar) anesthetics than for the (apolar) non-anesthetics. Anesthetics staying in this outer preferred position increase the lateral separation between the lipid molecules, giving rise to a decrease of the lateral density. The lower lateral density leads to an increased mobility of the DPPC molecules, a decreased order of their tails, an increase of the free volume around this outer preferred position, and a decrease of the lateral pressure at the hydrocarbon side of the apolar/polar interface, a change that might well be in a causal relation with the occurrence of the anesthetic effect. All these changes are clearly reverted by the increase of pressure. Furthermore, non-anesthetics occur in this outer preferred position in a considerably smaller concentration and hence either induce such changes in a much weaker form or do not induce them at all.
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Affiliation(s)
- Zsófia B Rózsa
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Milán Szőri
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - Balázs Fábián
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, CZ-16610 Prague 6, Czech Republic
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 6, H-3300 Eger, Hungary
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Faria MJ, Machado R, Ribeiro A, Gonçalves H, Real Oliveira MECD, Viseu T, das Neves J, Lúcio M. Rational Development of Liposomal Hydrogels: A Strategy for Topical Vaginal Antiretroviral Drug Delivery in the Context of HIV Prevention. Pharmaceutics 2019; 11:pharmaceutics11090485. [PMID: 31540519 PMCID: PMC6781289 DOI: 10.3390/pharmaceutics11090485] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/11/2019] [Accepted: 09/14/2019] [Indexed: 01/09/2023] Open
Abstract
HIV/AIDS stands as a global burden, and vaginal microbicides constitute a promising strategy for topical pre-exposure prophylaxis. Preceding the development of a microbicide containing tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC), in silico and in vitro studies were performed to evaluate the physicochemical characteristics of both drugs, and to study their biophysical impact in lipid model systems. Results from these pre-formulation studies defined hydrogels as adequate vehicles to incorporate TDF-loaded liposomes and FTC. After studying interactions with mucin, zwitterionic liposomes with a mean diameter of 134 ± 13 nm, an encapsulation TDF efficiency of approximately 84%, and a transition temperature of 41 °C were selected. The chosen liposomal formulation was non-cytotoxic to HEC-1-A and CaSki cells, and was able to favor TDF permeation across polysulfone membranes (Jss = 9.9 μg·cm-2·h-1). After the incorporation of TDF-loaded liposomes and FTC in carbomer hydrogels, the drug release profile was sustained over time, reaching around 60% for both drugs within 3-6 h, and best fitting the Weibull model. Moreover, liposomal hydrogels featured pseudoplastic profiles that were deemed suitable for topical application. Overall, the proposed liposomal hydrogels may constitute a promising formulation for the vaginal co-delivery of TDF/FTC.
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Affiliation(s)
- Maria J. Faria
- CF-UM-UP—Centro de Física das Universidades do Minho e Porto, Departamento de Física da Universidade do Minho, 4710-057 Braga, Portugal (T.V.)
| | - Raul Machado
- CBMA—Centro de Biologia Molecular e Ambiental, Departamento de Biologia, Universidade do Minho, 4710-057 Braga, Portugal;
- IB-S—Institute of Science and Innovation for Bio-Sustainability, Universidade do Minho, 4710-057 Braga, Portugal
| | - Artur Ribeiro
- CEB—Centro de Engenharia Biológica, Universidade do Minho, 4710-057 Braga, Portugal;
| | | | - Maria Elisabete C. D. Real Oliveira
- CF-UM-UP—Centro de Física das Universidades do Minho e Porto, Departamento de Física da Universidade do Minho, 4710-057 Braga, Portugal (T.V.)
| | - Teresa Viseu
- CF-UM-UP—Centro de Física das Universidades do Minho e Porto, Departamento de Física da Universidade do Minho, 4710-057 Braga, Portugal (T.V.)
| | - José das Neves
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
- INEB—Instituto de Engenharia Biomédica, Universidade do Porto, 4200-135 Porto, Portugal
- CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, 4585-116 Gandra, Portugal
- Correspondence: (J.d.N.); (M.L.); Tel.: +351-22-040-8800 (J.d.N.); +351-25-360-4060 (M.L.)
| | - Marlene Lúcio
- CF-UM-UP—Centro de Física das Universidades do Minho e Porto, Departamento de Física da Universidade do Minho, 4710-057 Braga, Portugal (T.V.)
- CBMA—Centro de Biologia Molecular e Ambiental, Departamento de Biologia, Universidade do Minho, 4710-057 Braga, Portugal;
- Correspondence: (J.d.N.); (M.L.); Tel.: +351-22-040-8800 (J.d.N.); +351-25-360-4060 (M.L.)
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Hantal G, Fábián B, Sega M, Jójárt B, Jedlovszky P. Effect of general anesthetics on the properties of lipid membranes of various compositions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:594-609. [PMID: 30571949 DOI: 10.1016/j.bbamem.2018.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/05/2018] [Accepted: 12/13/2018] [Indexed: 10/27/2022]
Abstract
Computer simulations of four lipid membranes of different compositions, namely neat DPPC and PSM, and equimolar DPPC-cholesterol and PSM-cholesterol mixtures, are performed in the presence and absence of the general anesthetics diethylether and sevoflurane both at 1 and 600 bar. The results are analyzed in order to identify membrane properties that are potentially related to the molecular mechanism of anesthesia, namely that change in the same way in any membrane with any anesthetics, and change oppositely with increasing pressure. We find that the lateral lipid density satisfies both criteria: it is decreased by anesthetics and increased by pressure. This anesthetic-induced swelling is attributed to only those anesthetic molecules that are located close to the boundary of the apolar phase. This lateral expansion is found to lead to increased lateral mobility of the lipids, an effect often thought to be related to general anesthesia; to an increased fraction of the free volume around the outer preferred position of anesthetics; and to the decrease of the lateral pressure in the nearby range of the ester and amide groups, a region into which anesthetic molecules already cannot penetrate. All these changes are reverted by the increase of pressure. Another important finding of this study is that cholesterol has an opposite effect on the membrane properties than anesthetics, and, correspondingly, these changes are less marked in the presence of cholesterol. Therefore, changes in the membrane that can lead to general anesthesia are expected to occur in the membrane domains of low cholesterol content.
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Affiliation(s)
- György Hantal
- Faculty of Physics, University of Vienna, Sensengasse 8/9, A-1090 Vienna, Austria
| | - Balázs Fábián
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary; Institut UTINAM (CNRS UMR 6213), Université Bourgogne Franche-Comté, 16 route de Gray, F-25030 Besançon, France
| | - Marcello Sega
- Faculty of Physics, University of Vienna, Sensengasse 8/9, A-1090 Vienna, Austria
| | - Balázs Jójárt
- Institute of Food Engineering, University of Szeged, Moszkvai krt 5-7, H-6725 Szeged, Hungary
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka utca 6, H-3300 Eger, Hungary.
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A Molecular Biophysical Approach to Diclofenac Topical Gastrointestinal Damage. Int J Mol Sci 2018; 19:ijms19113411. [PMID: 30384433 PMCID: PMC6275047 DOI: 10.3390/ijms19113411] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/23/2018] [Accepted: 10/26/2018] [Indexed: 11/17/2022] Open
Abstract
Diclofenac (DCF), the most widely consumed non-steroidal anti-inflammatory drug (NSAID) worldwide, is associated with adverse typical effects, including gastrointestinal (GI) complications. The present study aims to better understand the topical toxicity induced by DCF using membrane models that mimic the physiological, biophysical, and chemical environments of GI mucosa segments. For this purpose, phospholipidic model systems that mimic the GI protective lining and lipid models of the inner mitochondrial membrane were used together with a wide set of techniques: derivative spectrophotometry to evaluate drug distribution at the membrane; steady-state and time-resolved fluorescence to predict drug location at the membrane; fluorescence anisotropy, differential scanning calorimetry (DSC), dynamic light scattering (DLS), and calcein leakage studies to evaluate the drug-induced disturbance on membrane microviscosity and permeability; and small- and wide-angle X-ray scattering studies (SAXS and WAXS, respectively), to evaluate the effects of DCF at the membrane structure. Results demonstrated that DCF interacts chemically with the phospholipids of the GI protective barrier in a pH-dependent manner and confirmed the DCF location at the lipid headgroup region, as well as DCF’s higher distribution at mitochondrial membrane contact points where the impairment of biophysical properties is consistent with the uncoupling effects reported for this drug.
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Polley A. Partition of common anesthetic molecules in the liquid disordered phase domain of a composite multicomponent membrane. Phys Rev E 2018; 98:012409. [PMID: 30110859 DOI: 10.1103/physreve.98.012409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Indexed: 01/04/2023]
Abstract
Despite a vast clinical application of anesthetics, the molecular level of understanding of general anesthesia is far from our reach. Using atomistic molecular dynamics simulation, we study the effects of common anesthetics: ethanol, chloroform, and methanol in the fully hydrated symmetric multicomponent lipid bilayer membrane comprised of an unsaturated palmitoyl-oleoyl-phosphatidyl-choline (POPC), a saturated palmitoyl-sphingomyelin, and cholesterol, which exhibits phase coexistence of liquid-ordered (l_{o})-liquid-disordered (l_{d}) phase domains. We find that the mechanical and physical properties such as the thickness and rigidity of the membrane are reduced while the lateral expansion of the membrane is exhibited in the presence of anesthetic molecules. Our simulation shows both lateral and transverse heterogeneity of the anesthetics in the composite multicomponent lipid membrane. Both ethanol and chloroform partition in the POPC-rich l_{d} phase domain, while methanol is distributed in both l_{o}-l_{d} phase domains. Chloroform can penetrate deep into the membrane, while methanol partitions mostly at the water layer closed to the head group and ethanol at the neck of the lipids in the membrane.
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Affiliation(s)
- Anirban Polley
- Department of Chemical Engineering, Columbia University, New York City, New York 10027, USA
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Kuć M, Cieślik-Boczula K, Rospenk M. NIR studies of cholesterol-dependent structural modification of the model lipid bilayer doped with inhalation anesthetics. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.02.086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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7
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Local anesthetics induce interdigitation and thermotropic changes in dipalmitoylphosphatidylcholine bilayers. Chem Phys Lipids 2018; 210:22-27. [DOI: 10.1016/j.chemphyslip.2017.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/29/2017] [Accepted: 12/19/2017] [Indexed: 01/03/2023]
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Kuć M, Cieślik-Boczula K, Rospenk M. Anesthetic-dependent changes in the chain-melting phase transition of DPPG liposomes studied using near-infrared spectroscopy supported by PCA. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 186:37-43. [PMID: 28605687 DOI: 10.1016/j.saa.2017.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 05/18/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
The effect of inhalation anesthetics (enflurane, isoflurane, sevoflurane or halothane) on the lipid chain-melting phase transition of negatively charged phospholipid membranes was studied using near-infrared (NIR) spectroscopy supported by Principal Component Analysis (PCA). NIR spectra of anesthetics-mixed dipalmitoylphosphatidylglycerol (DPPG) membranes were recorded in a range of the first overtone of the symmetric and antisymmetric stretching vibrations of CH2 groups of lipid aliphatic chains as a function of increasing temperature. Anesthetic-dependent changes in the trans to gauche conformers ratio of CH2 groups in the hydrocarbon lipid chains were characterized in detail and compared with the zwitterionic lipid membranes, which were built of dipalmitoylphosphatidylcholine (DPPC) molecules.
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Affiliation(s)
- Marta Kuć
- Faculty of Chemistry, University of Wroclaw, Joliot- Curie 14, 50-383 Wroclaw, Poland
| | | | - Maria Rospenk
- Faculty of Chemistry, University of Wroclaw, Joliot- Curie 14, 50-383 Wroclaw, Poland
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Strohmeier A, Först G, Tauber P, Schubert R. Membrane/Water Partition Coefficients of Bile Salts Determined Using Laurdan as a Fluorescent Probe. Biophys J 2017; 111:1714-1723. [PMID: 27760358 DOI: 10.1016/j.bpj.2016.08.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/07/2016] [Accepted: 08/15/2016] [Indexed: 11/28/2022] Open
Abstract
The interaction of liposomal membranes composed of soybean phosphatidylcholine with the bile salts (BSs) cholate (Ch), glycocholate (GC), chenodeoxycholate (CDC), and glycochenodeoxycholate (GCDC) was studied. The BSs differed with regard to their lipophilicity, pKa values, and the size of their hydrophilic moiety. Their membrane interactions were investigated using Laurdan as a membrane-anchored fluorescent dye. The apparent membrane/water partition coefficient, D, at pH 7.4 was calculated from binding plots and compared with direct binding measurements using ultracentrifugation as a reference. The Laurdan-derived LogD values at pH 7.4 were found to be 2.10 and 2.25 for the trihydroxy BSs, i.e., Ch and GC, and 2.85 and 2.75 for the dihydroxy BSs, i.e., CDC and GCDC, respectively. For the membrane-associated glycine-conjugated GC and GCDC (pKa values of ∼3.9), no differences in the Laurdan spectra of the respective BS were found at pH 6.8, 7.4, and 8.2. Unconjugated Ch and CDC (pKa values of ∼5.0) showed pronounced differences at the three pH values. Furthermore, the kinetics of membrane adsorption and transbilayer movement differed between conjugated and unconjugated BSs as determined with Laurdan-labeled liposomes.
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Tsuchiya H. Anesthetic effects changeable in habitual drinkers: Mechanistic drug interactions with neuro-active indoleamine–aldehyde condensation products associated with alcoholic beverage consumption. Med Hypotheses 2016; 92:62-6. [DOI: 10.1016/j.mehy.2016.04.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 04/22/2016] [Indexed: 11/29/2022]
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Bizien T, Ameline JC, Yager KG, Marchi V, Artzner F. Self-Organization of Quantum Rods Induced by Lipid Membrane Corrugations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12148-12154. [PMID: 26467312 DOI: 10.1021/acs.langmuir.5b03335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Self-organization of fluorescent nanoparticles, using biological molecules such as phospholipids to control assembly distances, is a promising method for creating hybrid nanostructures. We report here the formation of hybrid condensed phases made of anisotropic nanoparticles and phospholipids. Such structure formation is driven by electrostatic interaction between the nanoparticles and the phospholipids, and results in the formation of a 2D rectangular liquid crystal, as confirmed by high-resolution Small-Angle X-ray Scattering (SAXS). Moreover, we show that the fluorescent properties of the NPs are not modified by the self-assembly process.
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Affiliation(s)
- Thomas Bizien
- Université de Rennes 1, CNRS UMR 6226, Institut des Sciences Chimiques de Rennes, Avenue du Général Leclerc, 35042 Rennes, France
- Université de Rennes 1, CNRS UMR 6251, Institut de Physique de Rennes, Avenue du Général Leclerc, 35042 Rennes, France
- Synchrotron SOLEIL l'Orme des Merisiers Saint-Aubin - BP 48 91192 Gif-sur-Yvette Cedex, France
| | - Jean-Claude Ameline
- Université de Rennes 1, CNRS UMR 6251, Institut de Physique de Rennes, Avenue du Général Leclerc, 35042 Rennes, France
| | - Kevin G Yager
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Valérie Marchi
- Université de Rennes 1, CNRS UMR 6226, Institut des Sciences Chimiques de Rennes, Avenue du Général Leclerc, 35042 Rennes, France
| | - Franck Artzner
- Université de Rennes 1, CNRS UMR 6251, Institut de Physique de Rennes, Avenue du Général Leclerc, 35042 Rennes, France
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Membrane Interactions of Phytochemicals as Their Molecular Mechanism Applicable to the Discovery of Drug Leads from Plants. Molecules 2015; 20:18923-66. [PMID: 26501254 PMCID: PMC6332185 DOI: 10.3390/molecules201018923] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/11/2015] [Accepted: 10/14/2015] [Indexed: 02/02/2023] Open
Abstract
In addition to interacting with functional proteins such as receptors, ion channels, and enzymes, a variety of drugs mechanistically act on membrane lipids to change the physicochemical properties of biomembranes as reported for anesthetic, adrenergic, cholinergic, non-steroidal anti-inflammatory, analgesic, antitumor, antiplatelet, antimicrobial, and antioxidant drugs. As well as these membrane-acting drugs, bioactive plant components, phytochemicals, with amphiphilic or hydrophobic structures, are presumed to interact with biological membranes and biomimetic membranes prepared with phospholipids and cholesterol, resulting in the modification of membrane fluidity, microviscosity, order, elasticity, and permeability with the potencies being consistent with their pharmacological effects. A novel mechanistic point of view of phytochemicals would lead to a better understanding of their bioactivities, an insight into their medicinal benefits, and a strategic implication for discovering drug leads from plants. This article reviews the membrane interactions of different classes of phytochemicals by highlighting their induced changes in membrane property. The phytochemicals to be reviewed include membrane-interactive flavonoids, terpenoids, stilbenoids, capsaicinoids, phloroglucinols, naphthodianthrones, organosulfur compounds, alkaloids, anthraquinonoids, ginsenosides, pentacyclic triterpene acids, and curcuminoids. The membrane interaction’s applicability to the discovery of phytochemical drug leads is also discussed while referring to previous screening and isolating studies.
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Fábián B, Darvas M, Picaud S, Sega M, Jedlovszky P. The effect of anaesthetics on the properties of a lipid membrane in the biologically relevant phase: a computer simulation study. Phys Chem Chem Phys 2015; 17:14750-60. [DOI: 10.1039/c5cp00851d] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phospholipid membranes containing four different general anaesthetic molecules are simulated in the biologically relevant Lα phase at atmospheric and high pressures.
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Affiliation(s)
- Balázs Fábián
- Laboratory of Interfaces and Nanosize Systems
- Institute of Chemistry
- Eötvös Loránd University
- H-1117 Budapest
- Hungary
| | - Mária Darvas
- SISSA
- Sector of Molecular and Statistical Biophysics
- 34136 Trieste
- Italy
| | - Sylvain Picaud
- Institut UTINAM (CNRS UMR 6213)
- Université de Franche-Comté
- F-25030 Besançon
- France
| | - Marcello Sega
- Institut für Computergestützte Biologische Chemie
- University of Vienna
- A-1090 Vienna
- Austria
| | - Pál Jedlovszky
- Laboratory of Interfaces and Nanosize Systems
- Institute of Chemistry
- Eötvös Loránd University
- H-1117 Budapest
- Hungary
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14
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Dehsorkhi A, Castelletto V, Hamley IW, Seitsonen J, Ruokolainen J. Interaction between a cationic surfactant-like peptide and lipid vesicles and its relationship to antimicrobial activity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14246-53. [PMID: 24156610 PMCID: PMC3836358 DOI: 10.1021/la403447u] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/22/2013] [Indexed: 05/21/2023]
Abstract
We investigate the properties of an antimicrobial surfactant-like peptide (Ala)6(Arg), A6R, containing a cationic headgroup. The interaction of this peptide with zwitterionic (DPPC) lipid vesicles is investigated using a range of microscopic, X-ray scattering, spectroscopic, and calorimetric methods. The β-sheet structure adopted by A6R is disrupted in the presence of DPPC. A strong effect on the small-angle X-ray scattering profile is observed: the Bragg peaks from the DPPC bilayers in the vesicle walls are eliminated in the presence of A6R and only bilayer form factor peaks are observed. All of these observations point to the interaction of A6R with DPPC bilayers. These studies provide insight into interactions between a model cationic peptide and vesicles, relevant to understanding the action of antimicrobial peptides on lipid membranes. Notably, peptide A6R exhibits antimicrobial activity without membrane lysis.
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Affiliation(s)
- Ashkan Dehsorkhi
- School of Chemistry, Pharmacy and Food Biosciences, University of Reading , Whiteknights, Reading, RG6 6AD, United Kingdom
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15
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Pereira-Leite C, Carneiro C, Soares JX, Afonso C, Nunes C, Lúcio M, Reis S. Biophysical characterization of the drug–membrane interactions: The case of propranolol and acebutolol. Eur J Pharm Biopharm 2013; 84:183-91. [DOI: 10.1016/j.ejpb.2012.12.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/11/2012] [Indexed: 11/16/2022]
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16
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Effects of surfactin on membrane models displaying lipid phase separation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:801-15. [DOI: 10.1016/j.bbamem.2012.11.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 10/19/2012] [Accepted: 11/05/2012] [Indexed: 01/02/2023]
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17
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Clustomesogens: Liquid Crystal Materials Containing Transition-Metal Clusters. Angew Chem Int Ed Engl 2010; 49:3351-5. [DOI: 10.1002/anie.201000325] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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18
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Molard Y, Dorson F, Cîrcu V, Roisnel T, Artzner F, Cordier S. Clustomesogens: Liquid Crystal Materials Containing Transition-Metal Clusters. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201000325] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Berchel M, Mériadec C, Lemiègre L, Artzner F, Jeftić J, Benvegnu T. Supramolecular Structures Based on New Bolaamphiphile Molecules Investigated by Small Angle and Wide Angle X-ray Scattering and Polarized Optical Microscopy. J Phys Chem B 2009; 113:15433-44. [DOI: 10.1021/jp905747r] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mathieu Berchel
- UMR CNRS 6226, Sciences Chimiques de Rennes, Equipe Chimie Organique et Supramoléculaire, Ecole Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, CS 50837, 35708 Rennes cedex 7, France, Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, 263, Avenue du Général Leclerc, 35042 Rennes cedex, France, and Université Européenne de Bretagne, 5 boulevard Laënnec, 35000 Rennes, France
| | - Cristelle Mériadec
- UMR CNRS 6226, Sciences Chimiques de Rennes, Equipe Chimie Organique et Supramoléculaire, Ecole Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, CS 50837, 35708 Rennes cedex 7, France, Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, 263, Avenue du Général Leclerc, 35042 Rennes cedex, France, and Université Européenne de Bretagne, 5 boulevard Laënnec, 35000 Rennes, France
| | - Loïc Lemiègre
- UMR CNRS 6226, Sciences Chimiques de Rennes, Equipe Chimie Organique et Supramoléculaire, Ecole Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, CS 50837, 35708 Rennes cedex 7, France, Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, 263, Avenue du Général Leclerc, 35042 Rennes cedex, France, and Université Européenne de Bretagne, 5 boulevard Laënnec, 35000 Rennes, France
| | - Franck Artzner
- UMR CNRS 6226, Sciences Chimiques de Rennes, Equipe Chimie Organique et Supramoléculaire, Ecole Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, CS 50837, 35708 Rennes cedex 7, France, Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, 263, Avenue du Général Leclerc, 35042 Rennes cedex, France, and Université Européenne de Bretagne, 5 boulevard Laënnec, 35000 Rennes, France
| | - Jelena Jeftić
- UMR CNRS 6226, Sciences Chimiques de Rennes, Equipe Chimie Organique et Supramoléculaire, Ecole Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, CS 50837, 35708 Rennes cedex 7, France, Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, 263, Avenue du Général Leclerc, 35042 Rennes cedex, France, and Université Européenne de Bretagne, 5 boulevard Laënnec, 35000 Rennes, France
| | - Thierry Benvegnu
- UMR CNRS 6226, Sciences Chimiques de Rennes, Equipe Chimie Organique et Supramoléculaire, Ecole Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, CS 50837, 35708 Rennes cedex 7, France, Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, 263, Avenue du Général Leclerc, 35042 Rennes cedex, France, and Université Européenne de Bretagne, 5 boulevard Laënnec, 35000 Rennes, France
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20
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Matsingou C, Demetzos C. Effect of the Nature of the 3β-Substitution in Manoyl Oxides on the Thermotropic Behavior of DPPC Lipid Bilayer and on DPPC Liposomes. J Liposome Res 2008; 17:89-105. [PMID: 17613699 DOI: 10.1080/08982100701375076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Functionalized manoyl oxide derivatives have been proved over the years to evoke several biological responses. Among them, 3beta-hydroxy-manoyl oxide (1) and 3beta-acetoxy-manoyl oxide (2) have been shown to exhibit in vitro antimicrobial and cytotoxic activity, while N-imidazole-3 beta-thiocarbonyl ester of manoyl oxide (3) was found to exhibit potent cytotoxic effect. Their partitioning into phospholipid bilayers may lead to membrane structure modifications that are crucial in liposome development as they may influence their maintenance and integrity. DSC was used to study the modifications induced in DPPC bilayers by incorporating increasing concentrations of the three manoyl oxide derivatives. All derivatives were found to strongly affect the bilayer structural organization in terms of a decrease of the cooperativity, the fluidization and partially destabilization of the gel phase and the induction of a lateral phase separation in clustering domains. Derivatives 1 and 3 were incorporated into DPPC liposomes and their physicochemical stability was monitored at 4 degrees C. The stability of liposomes was strongly influenced by the presence of 1 and 3 at any molar ratio studied. DPPC/1 liposomes were found to retain its stability for 48 h at low concentration of 10% mol, while at higher concentrations up to 30% mol they collapsed into aggregated material. In all cases DPPC/3 liposomes were found unstable and sticky aggregated structures precipitated from the bulk suspension.
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Affiliation(s)
- Christina Matsingou
- Department of Pharmaceutical Technology, School of Pharmacy, Panepistimiopolis, Zografou, University of Athens, Athens, Greece
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21
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Abstract
Fengycin is a biologically active lipopeptide produced by several Bacillus subtilis strains. The lipopeptide is known to develop antifungal activity against filamentous fungi and to have hemolytic activity 40-fold lower than that of surfactin, another lipopeptide produced by B. subtilis. The aim of this work is to use complementary biophysical techniques to reveal the mechanism of membrane perturbation by fengycin. These include: 1), the Langmuir trough technique in combination with Brewster angle microscopy to study the lipopeptide penetration into monolayers; 2), ellipsometry to investigate the adsorption of fengycin onto supported lipid bilayers; 3), differential scanning calorimetry to determine the thermotropic properties of lipid bilayers in the presence of fengycin; and 4), cryogenic transmission electron microscopy, which provides information on the structural organization of the lipid/lipopeptide system. From these experiments, the mechanism of fengycin action appears to be based on a two-state transition controlled by the lipopeptide concentration. One state is the monomeric, not deeply anchored and nonperturbing lipopeptide, and the other state is a buried, aggregated form, which is responsible for membrane leakage and bioactivity. The mechanism, thus, appears to be driven mainly by the physicochemical properties of the lipopeptide, i.e., its amphiphilic character and affinity for lipid bilayers.
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22
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Bernardi RC, Gomes DEB, Ito AS, Ota AT, Pascutti PG, Taft C. Density functional and molecular dynamics simulations of local anesthetics in 0.9% NaCl solution. MOLECULAR SIMULATION 2007. [DOI: 10.1080/08927020701620636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Bottier C, Géan J, Artzner F, Desbat B, Pézolet M, Renault A, Marion D, Vié V. Galactosyl headgroup interactions control the molecular packing of wheat lipids in Langmuir films and in hydrated liquid-crystalline mesophases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1526-40. [PMID: 17459332 DOI: 10.1016/j.bbamem.2007.02.021] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 02/19/2007] [Accepted: 02/21/2007] [Indexed: 10/23/2022]
Abstract
The behavior of the two major galactolipids of wheat endosperm, mono- (MGDG) and di-galactosyldiacylglycerol (DGDG) was studied in aqueous dispersion and at the air/liquid interface. The acyl chains of the pure galactolipids and their binary equimolar mixture are in the fluid or liquid expanded phase. SAXS measurements on liquid-crystalline mesophases associated with the electron density reconstructions show that the DGDG adopts a lamellar phase L(alpha) with parallel orientation of the headgroups with respect to the plane of the bilayer, whereas MGDG forms an inverse hexagonal phase H(II) with a specific organization of galactosyl headgroups. The equimolar mixture shows a different behavior from those previously described with formation of an Im3m cubic phase. In comparing monolayers composed of the pure galactolipids and their equimolar mixtures, PM-IRRAS spectra show significant differences in the optical properties and orientation of galactosyl groups with respect to the interface. Furthermore, Raman and FTIR spectroscopies show that the acyl chains of the galactolipid mixture are more ordered compared to those of the pure components. These results suggest strong interactions between MGDG and DGDG galactosyl headgroups and these specific physical properties of galactolipids are discussed in relation to their biological interest in wheat seed.
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Affiliation(s)
- C Bottier
- Groupe Matière Condensée et Matériaux, UMR CNRS 6626, Université Rennes I, Campus Beaulieu, Rennes, France
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24
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Matsingou C, Demetzos C. Calorimetric study on the induction of interdigitated phase in hydrated DPPC bilayers by bioactive labdanes and correlation to their liposome stability. Chem Phys Lipids 2007; 145:45-62. [PMID: 17116297 DOI: 10.1016/j.chemphyslip.2006.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 09/15/2006] [Accepted: 10/20/2006] [Indexed: 11/26/2022]
Abstract
Labd-7,13-dien-15-ol (1), labd-13-ene-8alpha,15-diol (2), and labd-14-ene-8,13-diol (sclareol) have been found to exhibit cytotoxic and cytostatic effects. Their partitioning into phospholipid bilayers may induce membrane structure modifications, crucial in the development of liposomes. DSC was used to elucidate the profile of modifications induced in DPPC bilayers by incorporating increasing concentrations of the labdanes. Labdanes 1, 2 and sclareol were incorporated into SUV liposomes composed of DPPC their physicochemical stability was monitored (4 degrees C) and was compared to liposomes incorporating cholesterol. All labdanes strongly affect the bilayer organization in a concentration dependent manner in terms of a decrease of the cooperativity, the fluidization and partially destabilization of the gel phase, the induction of a lateral phase separation and the possible existence of interdigitated domains in the bilayer. The physicochemical stability of liposomes was strongly influenced by the chemical features of the labdanes. The liposomal preparations were found to retain their stability at low labdane concentration (10 mol%), while at higher concentrations up to 30 mol% a profound decrease in intact liposomes occurred, and a possible existence of interdigitated sheets was concluded.
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Affiliation(s)
- Christina Matsingou
- Department of Pharmaceutical Technology, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou 15771, Athens, Greece
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25
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Boulmedais F, Bauchat P, Brienne MJ, Arnal I, Artzner F, Gacoin T, Dahan M, Marchi-Artzner V. Water-soluble pegylated quantum dots: from a composite hexagonal phase to isolated micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:9797-803. [PMID: 17073514 DOI: 10.1021/la061849h] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We present a simple method based on the dispersion of fluorescent quantum dots (QD) into a liquid crystal phase that provides either nanostructured material or isolated QD micelles depending on water concentration. The liquid-crystal phase was obtained by using a gallate amphiphile with a poly(ethylene glycol) chain as the polar headgroup, named I. The hydration of QD/I mixtures resulted in the formation of a composite hexagonal phase identified by small-angle X-ray scattering and by polarized light and fluorescence optical microscopy, showing a homogeneous distribution of fluorescence within hexagonal phase. This composite mesophase can be converted into isolated QD-I micelles by dilution in water. The fluorescent QD-I micelles, purified by size exclusion chromatography, are well monodisperse with a hydrodynamic diameter of 20-30 nm. Moreover, these QD do not show any nonspecific adsorption on lipid or cell membranes. By simply adjusting the water content, the PEG gallate amphiphile I provides a simple method to prepare a self-organized composite phase or pegylated water soluble QD micelles for biological applications.
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Affiliation(s)
- F Boulmedais
- Université de Rennes 1, Sciences Chimiques de Rennes, CNRS UMR 6226, Campus de Beaulieu, F-35042 Rennes Cedex, France
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26
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Matsingou C, Dimas K, Demetzos C. Design and development of liposomes incorporating a bioactive labdane-type diterpene. In vitro growth inhibiting and cytotoxic activity against human cancer cell lines. Biomed Pharmacother 2006; 60:191-9. [PMID: 16675195 DOI: 10.1016/j.biopha.2006.03.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 02/22/2006] [Accepted: 03/08/2006] [Indexed: 11/23/2022] Open
Abstract
The isolation and identification of bioactive compounds from natural sources has given insights in the discovery of new drugs against several diseases. Labdane-type diterpenes isolated from nature, have been investigated in the past for their pharmaceutical activities. Labd-7,13-dien-15-ol (1), a major lipophilic constituent of the resin 'ladano' was found to exhibit cytotoxic and cytostatic activity against cell lines derived from solid tumors with a profound activity on small lung cancer cells, DMS114. The present study, based on liposomal technology, aimed to develop a suitable carrier of compound 1 to overcome its water insolubility that inhibits further in vivo administration. Liposomes have been proved adequate drug carriers which enhance the solubility of water insoluble drugs and reduce possible side effects. Dipalmitoyl phosphatidylcholine (DPPC), egg phosphatidylcholine (EPC) and dipalmitoyl phosphatidylglycerol (DPPG) were used to prepare liposomes incorporating compound 1 at various molar ratios. Their physicochemical characteristics were determined and liposomes composed of EPC:DPPG 9:0.1 (molar ratio) was chosen as the most suitable carrier concerning their physical characteristics, stability, incorporation efficiency as well as the ability to retain the capture of compound 1 in the presence of RPMI-1640 medium. The activity of the liposomal formulation of compound 1 against human cancer cell lines was compared to that of its free form. The results showed that EPC:DPPG:1 9:0.1:5 (molar ratio) liposomal formulation maintained the pharmacological activity of 1, improved its water solubility and was justified as suitable formulation for in vivo administration of compound 1.
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Affiliation(s)
- Christina Matsingou
- Department of Pharmaceutical Technology, School of Pharmacy, Panepistimiopolis, Zografou 15771, University of Athens, Athens, Greece
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27
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Churbanova IY, Tronin A, Strzalka J, Gog T, Kuzmenko I, Johansson JS, Blasie JK. Monolayers of a model anesthetic-binding membrane protein: formation, characterization, and halothane-binding affinity. Biophys J 2006; 90:3255-66. [PMID: 16473900 PMCID: PMC1432115 DOI: 10.1529/biophysj.105.072348] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
hbAP0 is a model membrane protein designed to possess an anesthetic-binding cavity in its hydrophilic domain and a cation channel in its hydrophobic domain. Grazing incidence x-ray diffraction shows that hbAP0 forms four-helix bundles that are vectorially oriented within Langmuir monolayers at the air-water interface. Single monolayers of hbAP0 on alkylated solid substrates would provide an optimal system for detailed structural and dynamical studies of anesthetic-peptide interaction via x-ray and neutron scattering and polarized spectroscopic techniques. Langmuir-Blodgett and Langmuir-Schaeffer deposition and self-assembly techniques were used to form single monolayer films of the vectorially oriented peptide hbAP0 via both chemisorption and physisorption onto suitably alkylated solid substrates. The films were characterized by ultraviolet absorption, ellipsometry, circular dichroism, and polarized Fourier transform infrared spectroscopy. The alpha-helical secondary structure of the peptide was retained in the films. Under certain conditions, the average orientation of the helical axis was inclined relative to the plane of the substrate, approaching perpendicular in some cases. The halothane-binding affinity of the vectorially oriented hbAP0 peptide in the single monolayers, with the volatile anesthetic introduced into the moist vapor environment of the monolayer, was found to be similar to that for the detergent-solubilized peptide.
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Affiliation(s)
- Inna Y Churbanova
- Departments of Chemistry and Anesthesiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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28
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Roch A, Shlyonsky V, Goolaerts A, Mies F, Sariban-Sohraby S. Halothane Directly Modifies Na+ and K+ Channel Activities in Cultured Human Alveolar Epithelial Cells. Mol Pharmacol 2006; 69:1755-62. [PMID: 16399849 DOI: 10.1124/mol.105.021485] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During inhalational anesthesia, halogenated gases are in direct contact with the alveolar epithelium, in which they may affect transepithelial ion and fluid transport. The effects of halogenated gases in vivo on epithelial Na+ and K+ channels, which participate in alveolar liquid clearance, remain unclear. In the present study, the effects of halothane (1, 2, and 4% atm) on ion-channel function in cultured human alveolar cells were investigated using the patch-clamp technique. After exposure to 4% halothane, amiloride-sensitive whole-cell inward currents increased by 84+/-22%, whereas tetraethylammonium-sensitive outward currents decreased by 63+/-7%. These effects, which occurred within 30 s, remained for 30-min periods of exposure to the gas, were concentration-dependent, and were reversible upon washout. Pretreatment with amiloride prevented 90+/-7% of the increase in inward currents without change in outward currents, consistent with an activation of amiloride-sensitive epithelial sodium channels. Tetraethylammonium obliterated 90+/-9% of the effect of halothane on outward currents, without change in inward currents, indicating inhibition of Ca2+-activated K+ channels. These channels were identified in excised patches to be small-conductance Ca2+-activated K+ channels. These effects of halothane were not modified after the inhibition of cytosolic phospholipase A2 by aristolochic acid. Exposure of the cells to either trypsin or to low Na+ completely prevented the increase in amiloride-sensitive currents induced by halothane, suggesting a release of Na+ channels self-inhibition. Thus, halothane modifies differentially and independently Na+ and K+ permeabilities in human alveolar cells.
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Affiliation(s)
- Antoine Roch
- Laboratoire de Physiologie et Physiopathologie, Campus Erasme CP 604, 808, route de Lennik, Université Libre de Bruxelles, Belgium
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29
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Patra M, Salonen E, Terama E, Vattulainen I, Faller R, Lee BW, Holopainen J, Karttunen M. Under the influence of alcohol: the effect of ethanol and methanol on lipid bilayers. Biophys J 2005; 90:1121-35. [PMID: 16326895 PMCID: PMC1367264 DOI: 10.1529/biophysj.105.062364] [Citation(s) in RCA: 276] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Extensive microscopic molecular dynamics simulations have been performed to study the effects of short-chain alcohols, methanol and ethanol, on two different fully hydrated lipid bilayer systems (POPC and DPPC) in the fluid phase at 323 K. It is found that ethanol has a stronger effect on the structural properties of the membranes. In particular, the bilayers become more fluid and permeable: ethanol molecules are able to penetrate through the membrane in typical timescales of approximately 200 ns, whereas for methanol that timescale is considerably longer, at least of the order of microseconds. A closer examination exposes a number of effects due to ethanol. Hydrogen-bonding analysis reveals that a large fraction of ethanols is involved in hydrogen bonds with lipids. This in turn is intimately coupled to the ordering of hydrocarbon chains: we find that binding to an ethanol decreases the order of the chains. We have also determined the dependence of lipid-chain ordering on ethanol concentration and found that to be nonmonotonous. Overall, we find good agreement with NMR and micropipette studies.
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Affiliation(s)
- Michael Patra
- Biophysics and Statistical Mechanics Group, Laboratory of Computational Engineering, Helsinki University of Technology, Helsinki, Finland
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30
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Pickholz M, Saiz L, Klein ML. Concentration effects of volatile anesthetics on the properties of model membranes: a coarse-grain approach. Biophys J 2004; 88:1524-34. [PMID: 15613628 PMCID: PMC1305210 DOI: 10.1529/biophysj.104.044354] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To gain insights into the molecular level mechanism of drug action at the membrane site, we have carried out extensive molecular dynamics simulations of a model membrane in the presence of a volatile anesthetic using a coarse-grain model. Six different anesthetic (halothane)/lipid (dimyristoylphosphatidylcholine) ratios have been investigated, going beyond the low doses typical of medical applications. The volatile anesthetics were introduced into a preassembled fully hydrated 512-molecule lipid bilayer and each of the molecular dynamics simulations were carried out at ambient conditions, using the NPT ensemble. The area per lipid increases monotonically with the halothane concentration and the lamellar spacing decreases, whereas the lipid bilayer thickness shows no appreciable differences and only a slight increase upon addition of halothane. The density profiles of the anesthetic molecules display a bimodal distribution along the membrane normal with maxima located close to the lipid-water interface region. We have studied how halothane molecules fluctuate between the two maxima of the bimodal distribution and we observed a different mechanism at low and high anesthetic concentrations. Through the investigation of the reorientational motions of the lipid tails, we found that the anesthetic molecules increase the segmental order of the lipids close to the membrane surface.
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Affiliation(s)
- Mónica Pickholz
- Center for Molecular Modeling and Chemistry Department, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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31
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Ye S, Strzalka J, Churbanova IY, Zheng S, Johansson JS, Blasie JK. A model membrane protein for binding volatile anesthetics. Biophys J 2004; 87:4065-74. [PMID: 15465862 PMCID: PMC1304915 DOI: 10.1529/biophysj.104.051045] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Earlier work demonstrated that a water-soluble four-helix bundle protein designed with a cavity in its nonpolar core is capable of binding the volatile anesthetic halothane with near-physiological affinity (0.7 mM Kd). To create a more relevant, model membrane protein receptor for studying the physicochemical specificity of anesthetic binding, we have synthesized a new protein that builds on the anesthetic-binding, hydrophilic four-helix bundle and incorporates a hydrophobic domain capable of ion-channel activity, resulting in an amphiphilic four-helix bundle that forms stable monolayers at the air/water interface. The affinity of the cavity within the core of the bundle for volatile anesthetic binding is decreased by a factor of 4-3.1 mM Kd as compared to its water-soluble counterpart. Nevertheless, the absence of the cavity within the otherwise identical amphiphilic peptide significantly decreases its affinity for halothane similar to its water-soluble counterpart. Specular x-ray reflectivity shows that the amphiphilic protein orients vectorially in Langmuir monolayers at higher surface pressure with its long axis perpendicular to the interface, and that it possesses a length consistent with its design. This provides a successful starting template for probing the nature of the anesthetic-peptide interaction, as well as a potential model system in structure/function correlation for understanding the anesthetic binding mechanism.
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Affiliation(s)
- Shixin Ye
- Department of Chemistry, Department of Anesthesiology, University of Pennsylvania, Philadelphia, Pennsylvania
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