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Çetinel ZÖ, Bilge D. Investigation of miltefosine-model membranes interactions at the molecular level for two different PS levels modeling cancer cells. J Bioenerg Biomembr 2024; 56:461-473. [PMID: 38833041 PMCID: PMC11217121 DOI: 10.1007/s10863-024-10025-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 05/26/2024] [Indexed: 06/06/2024]
Abstract
Miltefosine (MLT) is a broad-spectrum drug included in the alkylphospholipids (APL) used against leishmania and various types of cancer. The most crucial feature of APLs is that they are thought to only kill cancerous cells without harming normal cells. However, the molecular mechanism of action of APLs is not completely understood. The increase in the phosphatidylserine (PS) ratio is a marker showing the stage of cancer and even metastasis. The goal of this research was to investigate the molecular effects of miltefosine at the molecular level in different PS ratios. The effects of MLT on membrane phase transition, membrane orders, and dynamics were studied using DPPC/DPPS (3:1) and DPPC/DPPS (1:1) multilayer (MLV) vesicles mimicking DPPS ratio variation, Differential Scanning Calorimetry (DSC), and Fourier Transform Infrared spectroscopy (FTIR). Our findings indicate that miltefosine is evidence at the molecular level that it is directed towards the tumor cell and that the drug's effect increases with the increase of anionic lipids in the membrane depending on the stage of cancer.
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Affiliation(s)
| | - Duygu Bilge
- Department of Physics, Faculty of Science, Ege University, Bornova, Izmir, 35100, Turkey.
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2
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Kitaoka H, Yokoyama Y, Sakka T, Nishi N. Salting-out and Competitive Adsorption of Ethanol into Lipid Bilayer Membranes: Conflicting Effects of Salts on Ethanol-Membrane Interactions Studied by Molecular Dynamics Simulations. J Phys Chem B 2024. [PMID: 39046846 DOI: 10.1021/acs.jpcb.4c03399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Small amphiphilic molecules, such as ethanol, disturb the structure of lipid bilayer membranes to increase the membrane permeability, which is important for applications such as drug delivery, disinfection, and fermentation. To investigate how and the extent to which coexisting salts affect membrane disturbance, we performed molecular dynamics (MD) simulations on lipid bilayer membranes composed of zwitterionic lipids in aqueous ethanol solutions containing 0-631 mM NaCl, KCl, and KI salts. The addition of salts at low concentrations induced cationic adsorption on the lipid membrane, which competes with ethanol adsorption, thereby reducing the hydrogen bonds between ethanol and lipid molecules. This competitive adsorption mitigated the membrane disturbance and decreased the permeation of ethanol molecules into the membrane. In contrast, higher salt concentrations enhanced the membrane disturbance and permeability, which was caused by the salting-out of ethanol from the aqueous phase to the lipid bilayer. These conflicting effects appearing at different concentrations were stronger with the chloride salts than with the iodide salt. Among the two chloride salts, NaCl and KCl, the latter showed a greater enhancement in ethanol permeation at high concentrations. This seeming anti-Hofmeister salting-out behavior resulted from greater Na+ adsorption, preventing the ethanol-lipid interactions.
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Affiliation(s)
- Haru Kitaoka
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Yuko Yokoyama
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
- iCaNS, Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Tetsuo Sakka
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
- iCaNS, Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Naoya Nishi
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
- iCaNS, Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
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3
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Dymond MK. A Membrane Biophysics Perspective on the Mechanism of Alcohol Toxicity. Chem Res Toxicol 2023. [PMID: 37186813 DOI: 10.1021/acs.chemrestox.3c00039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Motivations for understanding the underlying mechanisms of alcohol toxicity range from economical to toxicological and clinical. On the one hand, acute alcohol toxicity limits biofuel yields, and on the other hand, acute alcohol toxicity provides a vital defense mechanism to prevent the spread of disease. Herein the role that stored curvature elastic energy (SCE) in biological membranes might play in alcohol toxicity is discussed, for both short and long-chain alcohols. Structure-toxicity relationships for alcohols ranging from methanol to hexadecanol are collated, and estimates of alcohol toxicity per alcohol molecule in the cell membrane are made. The latter reveal a minimum toxicity value per molecule around butanol before alcohol toxicity per molecule increases to a maximum around decanol and subsequently decreases again. The impact of alcohol molecules on the lamellar to inverse hexagonal phase transition temperature (TH) is then presented and used as a metric to assess the impact of alcohol molecules on SCE. This approach suggests the nonmonotonic relationship between alcohol toxicity and chain length is consistent with SCE being a target of alcohol toxicity. Finally, in vivo evidence for SCE-driven adaptations to alcohol toxicity in the literature are discussed.
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Affiliation(s)
- Marcus K Dymond
- Chemistry Research and Enterprise Group, University of Brighton, Huxley Building, Lewes Road, Brighton BN2 4GJ, United Kingdom
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4
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Elibol B, Severcan M, Jakubowska-Dogru E, Dursun I, Severcan F. The structural effects of Vitamin A deficiency on biological macromolecules due to ethanol consumption and withdrawal: An FTIR study with chemometrics. JOURNAL OF BIOPHOTONICS 2022; 15:e202100377. [PMID: 35333440 DOI: 10.1002/jbio.202100377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
The structural effects of vitamin A-deficiency were examined on the molecular profiles of biomolecules of male rat hippocampus during prolonged ethanol intake/withdrawal using FT-IR spectroscopy coupled with chemometrics. Liquid ethanol diet with/without vitamin A was maintained to adult rats for 3-months. The rats were decapitated at different ethanol withdrawal times and FT-IR spectra were obtained. Ethanol consumption/withdrawal produced significant changes in proteins' conformations, while having insignificant structural effects on lipids. In vitamin A deficiency, ethanol produced structural changes in lipids by lipid ordering especially in the early-ethanol withdrawal. Furthermore, an increase in lipid and protein content, saturated/unsaturated lipid ratio, a decrease in nucleic acids content and decrease in membrane fluidity were observed. These changes were less severe in the presence of Vitamin A. This study is clinically important for individuals with vitamin A deficiency because they have to be more cautious when consuming alcohol to protect themselves from cognitive dysfunctions.
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Affiliation(s)
- Birsen Elibol
- Faculty of Medicine, Department of Medical Biology, Bezmialem Vakif University, Istanbul, Turkey
| | - Mete Severcan
- Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara, Turkey
| | - Ewa Jakubowska-Dogru
- Department of Biological Sciences, Middle East Technical University, Ankara, Turkey
| | - Ilknur Dursun
- Faculty of Medicine, Department of Physiology, Istinye University, Istanbul, Turkey
| | - Feride Severcan
- Department of Biological Sciences, Middle East Technical University, Ankara, Turkey
- Faculty of Medicine, Department of Biophysics, Altinbas University, Istanbul, Turkey
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5
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Zhang R, Cross TA, Peng X, Fu R. Surprising Rigidity of Functionally Important Water Molecules Buried in the Lipid Headgroup Region. J Am Chem Soc 2022; 144:7881-7888. [PMID: 35439409 PMCID: PMC9165019 DOI: 10.1021/jacs.2c02145] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Understanding water dynamics and structure is an important topic in biological systems. It is generally held in the literature that the interfacial water of hydrated phospholipids is highly mobile, in fast exchange with the bulk water ranging from the nano- to femtosecond timescale. Although nuclear magnetic resonance (NMR) is a powerful tool for structural and dynamic studies, direct probing of interfacial water in hydrated phospholipids is formidably challenging due to the extreme population difference between bulk and interfacial water. We developed a novel 17O solid-state NMR technique in combination with an ultra-high-field magnet (35.2 T) to directly probe the functionally important interfacial water. By selectively suppressing the dominant bulk water signal, we observed two distinct water species in the headgroup region of hydrated dimyristoylphosphatidylcholine (DMPC) lipid bilayers for the first time. One water species denoted as "confined water" is chemically and dynamically different from the bulk water (∼0.17 ppm downfield and a slightly shorter spin-lattice relaxation time). Another water species denoted as "bound water" has severely restricted motion and a distinct chemical shift (∼12 ppm upfield). Additionally, the bulk water is not as "free" as pure water, resulting from the fast exchange with the water molecules that weakly and transiently interact with the lipid choline groups. These new discoveries clearly indicate the existence of the interfacial water molecules that are relatively stable over the NMR timescale (on the order of milliseconds), providing an opportunity to characterize water dynamics on the millisecond or slower timescale in biomacromolecules.
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Affiliation(s)
- Rongfu Zhang
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States.,Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32301, United States
| | - Timothy A Cross
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States.,Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32301, United States
| | - Xinhua Peng
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Riqiang Fu
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
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6
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Wei X, Zang H, Guan Y, Yang C, Muncan J, Li L. Aquaphotomics investigation of the state of water in oral liquid formulation of traditional Chinese medicine and its dynamics during temperature perturbation. NEW J CHEM 2022. [DOI: 10.1039/d2nj03003a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three types of bound water with different hydrogen bonding strengths were identified and elucidated by aquaphotomics.
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Affiliation(s)
- Xiaoying Wei
- NMPA Key Laboratory for Technology Research and Evaluation of Drug Products, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Hengchang Zang
- NMPA Key Laboratory for Technology Research and Evaluation of Drug Products, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Yongxia Guan
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, Shandong, China
| | - Cui Yang
- NMPA Key Laboratory for Technology Research and Evaluation of Drug Products, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Jelena Muncan
- Aquaphotomics Research Department, Graduate School of Agricultural Science, Kobe University, Japan
| | - Lian Li
- NMPA Key Laboratory for Technology Research and Evaluation of Drug Products, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
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7
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Lairón-Peris M, Routledge SJ, Linney JA, Alonso-del-Real J, Spickett CM, Pitt AR, Guillamón JM, Barrio E, Goddard AD, Querol A. Lipid Composition Analysis Reveals Mechanisms of Ethanol Tolerance in the Model Yeast Saccharomyces cerevisiae. Appl Environ Microbiol 2021; 87:e0044021. [PMID: 33771787 PMCID: PMC8174666 DOI: 10.1128/aem.00440-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 03/23/2021] [Indexed: 12/30/2022] Open
Abstract
Saccharomyces cerevisiae is an important unicellular yeast species within the biotechnological and the food and beverage industries. A significant application of this species is the production of ethanol, where concentrations are limited by cellular toxicity, often at the level of the cell membrane. Here, we characterize 61 S. cerevisiae strains for ethanol tolerance and further analyze five representatives with various ethanol tolerances. The most tolerant strain, AJ4, was dominant in coculture at 0 and 10% ethanol. Unexpectedly, although it does not have the highest noninhibitory concentration or MIC, MY29 was the dominant strain in coculture at 6% ethanol, which may be linked to differences in its basal lipidome. Although relatively few lipidomic differences were observed between strains, a significantly higher phosphatidylethanolamine concentration was observed in the least tolerant strain, MY26, at 0 and 6% ethanol compared to the other strains that became more similar at 10%, indicating potential involvement of this lipid with ethanol sensitivity. Our findings reveal that AJ4 is best able to adapt its membrane to become more fluid in the presence of ethanol and that lipid extracts from AJ4 also form the most permeable membranes. Furthermore, MY26 is least able to modulate fluidity in response to ethanol, and membranes formed from extracted lipids are least leaky at physiological ethanol concentrations. Overall, these results reveal a potential mechanism of ethanol tolerance and suggest a limited set of membrane compositions that diverse yeast species use to achieve this. IMPORTANCE Many microbial processes are not implemented at the industrial level because the product yield is poorer and more expensive than can be achieved by chemical synthesis. It is well established that microbes show stress responses during bioprocessing, and one reason for poor product output from cell factories is production conditions that are ultimately toxic to the cells. During fermentative processes, yeast cells encounter culture media with a high sugar content, which is later transformed into high ethanol concentrations. Thus, ethanol toxicity is one of the major stresses in traditional and more recent biotechnological processes. We have performed a multilayer phenotypic and lipidomic characterization of a large number of industrial and environmental strains of Saccharomyces to identify key resistant and nonresistant isolates for future applications.
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Affiliation(s)
- M. Lairón-Peris
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology, CSIC, Valencia, Spain
| | - S. J. Routledge
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - J. A. Linney
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - J. Alonso-del-Real
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology, CSIC, Valencia, Spain
| | - C. M. Spickett
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - A. R. Pitt
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
- Manchester Institute of Biotechnology and Department of Chemistry, University of Manchester, Manchester, United Kingdom
| | - J. M. Guillamón
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology, CSIC, Valencia, Spain
| | - E. Barrio
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology, CSIC, Valencia, Spain
- Genetics Department, University of Valencia, Valencia, Spain
| | - A. D. Goddard
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - A. Querol
- Food Biotechnology Department, Institute of Agrochemistry and Food Technology, CSIC, Valencia, Spain
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8
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Aleskndrany A, Sahin I. The effects of Levothyroxine on the structure and dynamics of DPPC liposome: FTIR and DSC studies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183245. [DOI: 10.1016/j.bbamem.2020.183245] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 12/20/2022]
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9
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Rifici S, D’Angelo G, Crupi C, Branca C, Conti Nibali V, Corsaro C, Wanderlingh U. Influence of Alcohols on the Lateral Diffusion in Phospholipid Membranes. J Phys Chem B 2016; 120:1285-90. [DOI: 10.1021/acs.jpcb.5b11427] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simona Rifici
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Giovanna D’Angelo
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Cristina Crupi
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Caterina Branca
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Valeria Conti Nibali
- Institute
for Physical Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Carmelo Corsaro
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
| | - Ulderico Wanderlingh
- Dipartimento
di Fisica e Scienze della Terra, Università degli Studi di Messina, 98166 Messina, Italy
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10
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Effect of methanol on the phase-transition properties of glycerol-monopalmitate lipid bilayers investigated using molecular dynamics simulations: In quest of the biphasic effect. J Mol Graph Model 2015; 55:85-104. [DOI: 10.1016/j.jmgm.2014.10.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/29/2014] [Accepted: 10/30/2014] [Indexed: 11/21/2022]
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11
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Laner M, Horta BAC, Hünenberger PH. Long-timescale motions in glycerol-monopalmitate lipid bilayers investigated using molecular dynamics simulation. J Mol Graph Model 2014; 55:48-64. [PMID: 25437095 DOI: 10.1016/j.jmgm.2014.10.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 10/24/2022]
Abstract
The occurrence of long-timescale motions in glycerol-1-monopalmitate (GMP) lipid bilayers is investigated based on previously reported 600 ns molecular dynamics simulations of a 2×8×8 GMP bilayer patch in the temperature range 302-338 K, performed at three different hydration levels, or in the presence of the cosolutes methanol or trehalose at three different concentrations. The types of long-timescale motions considered are: (i) the possible phase transitions; (ii) the precession of the relative collective tilt-angle of the two leaflets in the gel phase; (iii) the trans-gauche isomerization of the dihedral angles within the lipid aliphatic tails; and (iv) the flipping of single lipids across the two leaflets. The results provide a picture of GMP bilayers involving a rich spectrum of events occurring on a wide range of timescales, from the 100-ps range isomerization of single dihedral angles, via the 100-ns range of tilt precession motions, to the multi-μs range of phase transitions and lipid-flipping events.
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Affiliation(s)
- Monika Laner
- Laboratory of Physical Chemistry, ETH Zürich, Zürich, Switzerland.
| | - Bruno A C Horta
- Laboratory of Physical Chemistry, ETH Zürich, Zürich, Switzerland; Dpto. de Engenharia Elétrica, PUC-Rio, Rio de Janeiro, Brazil; Dpto. de Ciências Biológicas, UEZO, Rio de Janeiro, Brazil.
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12
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Effect of the cosolutes trehalose and methanol on the equilibrium and phase-transition properties of glycerol-monopalmitate lipid bilayers investigated using molecular dynamics simulations. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:517-44. [DOI: 10.1007/s00249-014-0982-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/16/2014] [Accepted: 07/24/2014] [Indexed: 10/24/2022]
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13
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Rifici S, Corsaro C, Crupi C, Nibali VC, Branca C, D'Angelo G, Wanderlingh U. Lipid diffusion in alcoholic environment. J Phys Chem B 2014; 118:9349-55. [PMID: 25036819 DOI: 10.1021/jp504218v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We have studied the effects of a high concentration of butanol and octanol on the phase behavior and on the lateral mobility of 1,2-palmitoyl-sn-glycero-3-phosphocholine (DPPC) by means of differential scanning calorimetry and pulsed-gradient stimulated-echo (PGSTE) NMR spectroscopy. A lowering of the lipid transition from the gel to the liquid-crystalline state for the membrane-alcohol systems has been observed. NMR measurements reveal three distinct diffusions in the DPPC-alcohol systems, characterized by a high, intermediate, and slow diffusivity, ascribed to the water, the alcohol, and the lipid, respectively. The lipid diffusion process is promoted in the liquid phase while it is hindered in the interdigitated phase due to the presence of alcohols. Furthermore, in the interdigitated phase, lipid lateral diffusion coefficients show a slight temperature dependence. To the best of our knowledge, this is the first time that lateral diffusion coefficients on alcohol with so a long chain, and at low temperatures, are reported. By the Arrhenius plots of the temperature dependence of the diffusion coefficients, we have evaluated the apparent activation energy in both the liquid and in the interdigitated phase. The presence of alcohol increases this value in both phases. An explanation in terms of a free volume model that takes into account also for energy factors is proposed.
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Affiliation(s)
- Simona Rifici
- Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina , Messina, Italy
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14
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Tian K, Li H, Ye S. Methanol Perturbing Modeling Cell Membranes Investigated using Linear and Nonlinear Vibrational Spectroscopy. CHINESE J CHEM PHYS 2013. [DOI: 10.1063/1674-0068/26/01/27-34] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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15
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Dinsdale MG, Lloyd D, Jarvis B. YEAST VITALITY DURING CIDER FERMENTATION: TWO APPROACHES TO THE MEASUREMENT OF MEMBRANE POTENTIAL. JOURNAL OF THE INSTITUTE OF BREWING 2013. [DOI: 10.1002/j.2050-0416.1995.tb00883.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Liu M, Law WC, Kopwitthaya A, Liu X, Swihart MT, Prasad PN. Exploring the amphiphilicity of PEGylated gold nanorods: mechanical phase transfer and self-assembly. Chem Commun (Camb) 2013; 49:9350-2. [DOI: 10.1039/c3cc45103h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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17
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Rajagopal S, Fang H, Lynch C, Sando J, Kamatchi G. Effects of isoflurane on the expressed Cav2.2 currents in Xenopus oocytes depend on the activation of protein kinase C δ and its phosphorylation sites in the Cav2.2α1 subunits. Neuroscience 2011; 182:232-40. [DOI: 10.1016/j.neuroscience.2011.02.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 02/12/2011] [Accepted: 02/18/2011] [Indexed: 11/26/2022]
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18
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Geerke DP, van Gunsteren WF, Hünenberger PH. Molecular dynamics simulations of the interaction between polyhydroxylated compounds and Lennard-Jones walls: preferential affinity/exclusion effects and their relevance for bioprotection. MOLECULAR SIMULATION 2010. [DOI: 10.1080/08927021003752804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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19
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Orsi M, Sanderson WE, Essex JW. Permeability of small molecules through a lipid bilayer: a multiscale simulation study. J Phys Chem B 2009; 113:12019-29. [PMID: 19663489 DOI: 10.1021/jp903248s] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The transmembrane permeation of eight small (molecular weight <100) organic molecules across a phospholipid bilayer is investigated by multiscale molecular dynamics simulation. The bilayer and hydrating water are represented by simplified, efficient coarse-grain models, whereas the permeating molecules are described by a standard atomic-level force-field. Permeability properties are obtained through a refined version of the z-constraint algorithm. By constraining each permeant at selected depths inside the bilayer, we have sampled free energy differences and diffusion coefficients across the membrane. These data have been combined, according to the inhomogeneous solubility-diffusion model, to yield the permeability coefficients. The results are generally consistent with previous atomic-level calculations and available experimental data. Computationally, our multiscale approach proves 2 orders of magnitude faster than traditional atomic-level methods.
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Affiliation(s)
- Mario Orsi
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ United Kingdom
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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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Himmel HM. Mechanisms Involved in Cardiac Sensitization by Volatile Anesthetics: General Applicability to Halogenated Hydrocarbons? Crit Rev Toxicol 2008; 38:773-803. [DOI: 10.1080/10408440802237664] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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22
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Pereira CS, Hünenberger PH. The influence of polyhydroxylated compounds on a hydrated phospholipid bilayer: a molecular dynamics study. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020701784762] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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23
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Weis M, Kopáni M. Influence of vitamin C on alcohol binding to phospholipid monolayers. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2008; 37:893-901. [PMID: 18365189 DOI: 10.1007/s00249-008-0303-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 02/22/2008] [Accepted: 03/07/2008] [Indexed: 10/22/2022]
Abstract
The simple model of the biological membrane is provided by well-controlled lipid monolayers at the air-water interface. The Maxwell displacement current technique (MDC) provides novel approach to conformation study of the membrane models. The effect of alcohols is interaction with membrane molecules, mainly with the lipid head group and consequent changes in physical-chemical properties of the membrane. The aim of study is to detect changes in structural, electrical and mechanical properties of dipalmitoyl-phosphatidylcholine (DPPC) monolayer on the subphase of methanol-water and ethanol-water mixtures before and after addition of antioxidant agent, vitamin C. Monolayers properties are investigated by a surface pressure analysis (including mechanical properties evaluation) and the Maxwell displacement current measurement, the dipole moment projection calculation. Surface pressure-area isotherms show similar behaviour of the DPPC monolayer on alcohol-water mixtures independently on presence of vitamin C. Binding/adsorption process induces change of electron density distribution across monolayer and thus the molecular dipole moment. We observe small or negligible binding of methanol molecules on oxygen bonds of DPPC. Thus the antioxidant, vitamin C, has no significant effect. For ethanol-water mixtures is observed recovery of electrical properties in presence of antioxidant agent. We suppose that vitamin C regulates DPPC-ethanol molecules interaction.
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Affiliation(s)
- M Weis
- Department of Physics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 81219, Bratislava, Slovakia
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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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Koukoulitsa C, Kyrikou I, Demetzos C, Mavromoustakos T. The role of the anticancer drug vinorelbine in lipid bilayers using differential scanning calorimetry and molecular modeling. Chem Phys Lipids 2006; 144:85-95. [PMID: 16962086 DOI: 10.1016/j.chemphyslip.2006.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 07/13/2006] [Accepted: 07/17/2006] [Indexed: 11/26/2022]
Abstract
Differential scanning calorimetry (DSC) has been employed to investigate the thermal changes caused by the anticancer alkaloid drug vinorelbine in dipalmytoylphosphatidylcholine (DPPC) bilayers. The total enthalpy change was increased by the presence of the drug molecule, indicating a partial interdigitation of the lipid alkyl chains. The presence of cholesterol in DPPC bilayers including vinorelbine induced an obstruction of the interdigitation, since cholesterol interrupts the upraise of enthalpy change. Vinorelbine's interdigitation ability and stabilizing properties with the active site of the receptor have been compared with those of similar in structure amphipathic and bulky alkaloid vinblastine. The obtained results may in part explain their similar mechanism of action but different bioactivity.
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Affiliation(s)
- C Koukoulitsa
- Institute of Organic and Pharmaceutical Chemistry, Vas. Constantinou 48, 11635 Athens, Greece
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26
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Arrondo JLR, Coto X, Milicua JCG, Kveder M, Pifat G. Interaction of alcohols with serum LDL. Chem Phys Lipids 2006; 141:205-15. [PMID: 16620801 DOI: 10.1016/j.chemphyslip.2006.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Accepted: 02/20/2006] [Indexed: 11/17/2022]
Abstract
The interaction of low molecular weight alcohols with low density lipoprotein (LDL) has been studied using amide I band-fitting, thermal profiling and two-dimensional infrared correlation spectroscopy (2D-IR). At 0.3 M alcohol, no changes in secondary structure are observed. In the presence of 1 M alcohol, ethanol and propanol decreases protein denaturation temperature and produces changes in the amide I thermal profiles of protein components and in the lipid bands. The 2D-IR synchronous map corresponding to protein or lipid component at 20-37 degrees C suggests differences in the presence of propanol. The asynchronous map corresponding to the lipid component indicates changes in bandwidth, compatible with a more fluid environment. In the 37-80 degrees C temperature range the thermal profile is different in the presence of propanol, both for the lipid and protein components. The results presented show that when alcohols affect the protein component, the lipid spectrum also varies pointing to an effect on the lipid-protein interaction.
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27
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Nishitani Y, Matsumoto H. Ethanol rapidly causes activation of JNK associated with ER stress under inhibition of ADH. FEBS Lett 2005; 580:9-14. [PMID: 16343492 DOI: 10.1016/j.febslet.2005.11.030] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 11/02/2005] [Accepted: 11/11/2005] [Indexed: 12/11/2022]
Abstract
Acute ethanol loading causes oxidative stress to activate cell-death signaling via c-Jun NH2-terminal kinase (JNK) in livers. JNK are stimulated under conditions of endoplasmic reticulum (ER) stress which causes programmed cell death. However, no remarked cell death was observed in acute ethanol intoxication. Akt, one of the cell survival protein kinases, may be activated under ethanol loading. The aim of this study was to estimate activation of JNK and ER stress, role of ethanol metabolism on the activation, and association of JNK with Akt under acute ethanol loading using the perfused rat liver system. Activation of JNK or Akt and association of JNK and Akt with JNK interacting protein 1 were estimated by immunoprecipitation and immunoblotting. Expression of 78 kDa glucose-regulated protein (GRP78) mRNA, a biomarker of ER stress, was detected by quantitative real-time RT-PCR. Activations of JNK and Akt were enhanced by co-treatment with ethanol and a classical inhibitor of alcohol dehydrogenase (ADH). Addition of an antioxidant reduced the activation of JNK. Ethanol loading with ADH inhibition causes down-regulation of GRP78 mRNA levels. Therefore, these findings suggest first revelation that inhibition of ethanol metabolism complicates oxidative and ER stresses produced by ethanol.
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Affiliation(s)
- Yoko Nishitani
- Department of Legal Medicine, Sapporo Medical University School of Medicine, S-1 W-17, Chuo-ku, Sapporo 060-8556, Japan
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28
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Tierney KJ, Block DE, Longo ML. Elasticity and phase behavior of DPPC membrane modulated by cholesterol, ergosterol, and ethanol. Biophys J 2005; 89:2481-93. [PMID: 16055540 PMCID: PMC1366747 DOI: 10.1529/biophysj.104.057943] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Giant vesicles formed of 1,2-dipalmitoylphosphatidylcholine (DPPC) and sterols (cholesterol or ergosterol) in water and water/ethanol solutions have been used to examine the effect of sterol composition and ethanol concentration on the area compressibility modulus (K(a)), overall mechanical behavior, vesicle morphology, and induction of lipid alkyl chain interdigitation. Our results from micropipette aspiration suggest that cholesterol and ergosterol impact the order and microstructure of the gel (L(beta)') phase DPPC membrane. At low concentration (10-15 mol%) these sterols disrupt the long-range lateral order and fluidize the membrane (K(a) approximately 300 mN/m). Then at 18 mol%, these sterols participate in the formation of a continuous cohesive liquid-ordered (L(o)) phase with a sterol-dependent membrane density (K(a) approximately 750 for DPPC/ergosterol and K(a) approximately 1100 mN/m for DPPC/cholesterol). Finally at approximately 40 mol% both cholesterol and ergosterol impart similar condensation to the membrane (K(a) approximately 1200 mN/m). Introduction of ethanol (5-25 vol%) results in drops in the magnitude of K(a), which can be substantial, and sometimes individual vesicles with lowered K(a) reveal two slopes of tension versus apparent area strain. We postulate that this behavior represents disruption of lipid-sterol intermolecular interactions and therefore the membrane becomes interdigitation prone. We find that for DPPC vesicles with sterol concentrations of 20-25 mol%, significantly more ethanol is required to induce interdigitation compared to pure DPPC vesicles; approximately 7 vol% more for ergosterol and approximately 10 vol% more for cholesterol. For lower sterol concentrations (10-15 mol%), interdigitation is offset, but by <5 vol%. These data support the idea that ergosterol and cholesterol do enhance survivability for cells exposed to high concentrations of ethanol and provide evidence that the appearance of the interdigitated (L(beta)I) phase bilayer is a major factor in the disruption of cellular activity, which typically occurs between approximately 12 and approximately 16 vol% ethanol in yeast fermentations. We summarize our findings by producing, for the first time, "elasticity/phase diagrams" over a wide range of sterol (cholesterol and ergosterol) and ethanol concentrations.
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Affiliation(s)
- Kara J Tierney
- Department of Chemical Engineering and Materials Science, and Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
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29
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Abstract
In this study we introduce a mesoscopic lipid-water-alcohol model. Dissipative particle dynamics (DPD) simulations have been used to investigate the induced interdigitation of bilayers consisting of double-tail lipids by adding alcohol molecules to the bilayer. Our simulations nicely reproduce the experimental phase diagrams. We find that alcohol can induce an interdigitated structure where the common bilayer structure changes into monolayer in which the alcohol molecules screen the hydrophobic tails from the water phase. At low concentrations of alcohol the membrane has domains of the interdigitated phase that are in coexistence with the common membrane phase. We compute the effect of the chain length of the alcohol on the phase behavior of the membrane and show that the stability of the interdigitated phase depends on the length of the alcohol. We show that we can reproduce the experimental hydrophobic thickness of the bilayer for various combinations of lipids and alcohols. We use our model to clarify some of the experimental questions related to the structure of the interdigitated phase and put forward a simple model that explains the alcohol chain length dependence of the stability of this interdigitated phase.
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Affiliation(s)
- Marieke Kranenburg
- Department of Chemical Engineering, University of Amsterdam, Amsterdam 1018WV, The Netherlands
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30
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Ly HV, Longo ML. The influence of short-chain alcohols on interfacial tension, mechanical properties, area/molecule, and permeability of fluid lipid bilayers. Biophys J 2005; 87:1013-33. [PMID: 15298907 PMCID: PMC1304443 DOI: 10.1529/biophysj.103.034280] [Citation(s) in RCA: 219] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We used micropipette aspiration to directly measure the area compressibility modulus, bending modulus, lysis tension, lysis strain, and area expansion of fluid phase 1-stearoyl, 2-oleoyl phosphatidylcholine (SOPC) lipid bilayers exposed to aqueous solutions of short-chain alcohols at alcohol concentrations ranging from 0.1 to 9.8 M. The order of effectiveness in decreasing mechanical properties and increasing area per molecule was butanol>propanol>ethanol>methanol, although the lysis strain was invariant to alcohol chain-length. Quantitatively, the trend in area compressibility modulus follows Traube's rule of interfacial tension reduction, i.e., for each additional alcohol CH(2) group, the concentration required to reach the same area compressibility modulus was reduced roughly by a factor of 3. We convert our area compressibility data into interfacial tension values to: confirm that Traube's rule is followed for bilayers; show that alcohols decrease the interfacial tension of bilayer-water interfaces less effectively than oil-water interfaces; determine the partition coefficients and standard Gibbs adsorption energy per CH(2) group for adsorption of alcohol into the lipid headgroup region; and predict the increase in area per headgroup as well as the critical radius and line tension of a membrane pore for each concentration and chain-length of alcohol. The area expansion predictions were confirmed by direct measurements of the area expansion of vesicles exposed to flowing alcohol solutions. These measurements were fitted to a membrane kinetic model to find membrane permeability coefficients of short-chain alcohols. Taken together, the evidence presented here supports a view that alcohol partitioning into the bilayer headgroup region, with enhanced partitioning as the chain-length of the alcohol increases, results in chain-length-dependent interfacial tension reduction with concomitant chain-length-dependent reduction in mechanical moduli and membrane thickness.
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Affiliation(s)
- Hung V Ly
- Department of Chemical Engineering and Material Science, University of California, Davis, California, USA
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31
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Kubo I, Fujita T, Kubo A, Fujita KI. Modes of antifungal action of alkanols against Saccharomyces cerevisiae. Bioorg Med Chem 2003; 11:1117-22. [PMID: 12614899 DOI: 10.1016/s0968-0896(02)00453-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Primary aliphatic alcohols from C(6) to C(13) were tested for their antifungal activity against Saccharomyces cerevisiae. Undecanol was found to be the most potent fungicide followed by decanol. The time-kill curve study showed that undecanol was fungicidal against S. cerevisiae at any growth stages. This fungicidal activity was not influenced by pH values. The alcohols tested inhibited glucose-induced acidification by inhibiting the plasma membrane H(+)-ATPase. The primary antifungal action of amphipathic medium-chain (C(9)-C(12)) alkanols comes mainly from their ability as nonionic surfactants to disrupt the native membrane-associated function of the integral proteins. Hence, the antifungal activity of alkanols is mediated by biophysical process, and the maximum activity can be obtained when balance between hydrophilic and hydrophobic portions becomes the most appropriate.
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Affiliation(s)
- Isao Kubo
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3112, USA.
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32
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Yoshida T, Yamamoto Y, Taga K, Kamaya H, Ueda I. Effects of Water-Soluble Alcohols on the Surface Conductance of Lipid Monolayers: Bimodal Action. J Phys Chem B 2003. [DOI: 10.1021/jp0221845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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33
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Bonnefont-Rousselot D, Rouscilles A, Bizard C, Delattre J, Jore D, Gardès-Albert M. Antioxidant effect of ethanol toward in vitro peroxidation of human low-density lipoproteins initiated by oxygen free radicals. Radiat Res 2001; 155:279-87. [PMID: 11175662 DOI: 10.1667/0033-7587(2001)155[0279:aeoeti]2.0.co;2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This study was designed to evaluate the effect of ethanol on the peroxidation of human low-density lipoprotein (LDL) initiated by oxygen free radicals (O(2)(.-) and (.)OH in the absence of ethanol; O(2)(.-) and ethanol-derived peroxyl radicals, RO(2)(.), in the presence of ethanol) generated by gamma radiolysis. Initial radiolytic yields as determined by several markers of lipid peroxidation [i.e. decrease in endogenous antioxidants alpha-tocopherol and beta-carotene, formation of conjugated dienes and of thiobarbituric acid-reactive substances (TBARS)] were determined in 3 g liter(-1) LDLs (expressed as total LDL concentration) in the absence of ethanol or its presence at six different concentrations (0.42-17 x 10(-2) mol liter(-1)). Ethanol acted as an antioxidant by decreasing the rate of consumption of LDL endogenous antioxidants and the yields of formation of lipid peroxidation products, and by delaying the onset of the propagation phase for conjugated dienes and TBARS. With regard to the different markers studied, except for alpha-tocopherol and beta-carotene consumption, the effect of ethanol did not appear to be dependent on its concentration. Indeed, (.)OH were scavenged by ethanol at the lowest ethanol concentration (0.42 x 10(-2) mol liter(-1)), leading to RO(2)(.). These RO(2)(.) resulted in lower radiation-induced yields related to endogenous antioxidant consumption or to formation of lipid peroxidation products (for example, approximately 10% of RO(2)(.) oxidized LDLs from TBARS). Thus, under our in vitro conditions, ethanol behaved as an antioxidant when added to the LDL solutions. This should be taken into account in the reported antioxidant activity of wine. This is also of interest when lipophilic compounds have to be added as ethanolic solutions to LDLs to evaluate in vitro their antioxidant activity toward LDL peroxidation.
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Affiliation(s)
- D Bonnefont-Rousselot
- Laboratoire de Biochimie, Hôpital de la Salpêtrière, 47, bld de l'Hôpital, 75651 Paris Cedex 13, France
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34
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Westh P, Trandum C, Koga Y. Binding of small alcohols to a lipid bilayer membrane: does the partitioning coefficient express the net affinity? Biophys Chem 2001; 89:53-63. [PMID: 11246745 DOI: 10.1016/s0301-4622(00)00218-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The total vapor pressures at 26 degreesC of binary (water-alcohol) and ternary (water-alcohol-vesicle) systems were measured for six short chain alcohols. The vesicles were unilamellar dipalmitoyl phosphatidylcholine (DMPC). The data was used to evaluate the effect of vesicles on the chemical potential of alcohols expressed as the preferential binding parameter of the alcohol-lipid interaction, gamma23. This quantity is a thermodynamic (model-free) measure of the net strength of membrane-alcohol interactions. For the smaller investigated alcohols (methanol, ethanol and 1-propanol) gamma23 was negative. This is indicative of so-called preferential hydration, a condition where the affinity of the membrane for water is higher than the affinity for the alcohol. For the longer alcohols (1-butanol, 1-pentanol, 1-hexanol) gamma23 was positive and increasing with increasing chain length. This demonstrates preferential binding, i.e. enrichment of alcohol in the membrane and a concomitant depletion of the solute in the aqueous bulk. The measured values of gamma23 were compared to the number of alcohol-membrane contacts specified by partitioning coefficients from the literature. It was found that for the small alcohols the number of alcohol-membrane contacts is much larger than the number of preferentially bound solutes. This discrepancy, which is theoretically expected in cases of very weak binding, becomes less pronounced with increasing alcohol chain length, and when the partitioning coefficient exceeds approximately 3 on the molal scale (10(2) in mole fraction units) it vanishes. Based on this, relationships between structural and thermodynamic interpretations of membrane partitioning are discussed.
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Affiliation(s)
- P Westh
- Department of Life Sciences and Chemistry, Roskilde University, Denmark.
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35
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Yoshida T, Inagaki H, Kamya H, Ueda I. Two Types of Protein Hydration Measured by Dielectric Dispersion in the Gigahertz Region, and Effects of Anesthetics. J Phys Chem B 2000. [DOI: 10.1021/jp0021594] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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36
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Fein G, Meyerhoff DJ. Ethanol in Human Brain by Magnetic Resonance Spectroscopy: Correlation With Blood and Breath Levels, Relaxation, and Magnetization Transfer. Alcohol Clin Exp Res 2000. [DOI: 10.1111/j.1530-0277.2000.tb02088.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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37
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Kveder M, Pifat G, Jelovecki A, Klaić B, Pecar S, Schara M. The EPR study of LDL perturbed by alcohols with different molecular architecture. Alcohol 2000; 21:141-7. [PMID: 10963937 DOI: 10.1016/s0741-8329(00)00082-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this work, the interaction of different isomers of lower aliphatic alcohols with LDL representing a complex macromolecular assembly is investigated in vitro. Emphasis is given to the comparison of the impact of molecular architecture of methanol, ethanol, propanol (n-, iso-) and butanol (n-, iso-, sec-, tert-) in perturbing the lipid-protein assembly. The geometrical characteristics as well as the lipophilicity of the respective alcohol are considered. The EPR method combined with the spin labeling of both the apoB and the lipid monolayer allowed parallel detection of changes provoked in both phases. In addition to the change in protein environment, the spectral decomposition of the experimental data revealed a decrease in lipid ordering with the increasing concentration of the alcohols. This phenomenon for aliphatic alcohols is linearly correlated with the equal volume occupation (EVO) of alcohol in LDL. The results support the molecular mechanism of alcohol action through its interference with the lipid-protein interactions in LDL, which could be applicable to the molecular mechanism of alcohol interaction with integral membrane proteins.
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Affiliation(s)
- M Kveder
- Ruder Bosković Institute, FK/LMR, Bijenicka 54, 10000 Zagreb, Croatia
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38
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Smondyrev AM, Berkowitz ML. Molecular dynamics simulation of dipalmitoylphosphatidylcholine membrane with cholesterol sulfate. Biophys J 2000; 78:1672-80. [PMID: 10733950 PMCID: PMC1300764 DOI: 10.1016/s0006-3495(00)76719-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Using the molecular dynamics simulation technique, we studied the changes occurring in a dipalmitoylphosphatidylcholine (DPPC):cholesterol (CH) membrane at 50 mol% sterol when cholesterol is replaced with cholesterol sulfate (CS). Our simulations were performed at constant pressure and temperature on a nanosecond time scale. We found that 1) the area per DPPC:CS heterodimer is greater than the area of the DPPC:CH heterodimer; 2) CS increases ordering of DPPC acyl chains, but to a lesser extent than CH; 3) the number of hydrogen bonds between DPPC and water is decreased in a CS-containing membrane, but CS forms more water hydrogen bonds than CH; and 4) the membrane dipole potential reverses its sign for a DPPC-CS membrane compared to a DPPC-CH bilayer. We also studied the changes occurring in lipid headgroup conformations and determined the location of CS molecules in the membrane. Our results are in good agreement with the data available from experiments.
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Affiliation(s)
- A M Smondyrev
- Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599, USA
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39
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Mitchell DC, Litman BJ. Effect of ethanol and osmotic stress on receptor conformation. Reduced water activity amplifies the effect of ethanol on metarhodopsin II formation. J Biol Chem 2000; 275:5355-60. [PMID: 10681509 DOI: 10.1074/jbc.275.8.5355] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The combined effects of ethanol and osmolytes on both the extent of formation of metarhodopsin II (MII), which binds and activates transducin, and on acyl chain packing were examined in rod outer segment disc membranes. The ethanol-induced increase in MII formation was amplified by the addition of neutral osmolytes. This enhancement was linear with osmolality. At 360 milliosmolal, the osmolality of human plasma, 50 mM ethanol was 2.7 times more potent than at 0 osmolality, demonstrating the importance of water activity in in vitro experiments dealing with ethanol potency. Ethanol disordered acyl chain packing, and increasing osmolality enhanced this acyl chain disordering. Prior osmotic stress data showed a release of 35 +/- 2 water molecules upon MII formation. Ethanol increases this number to 49 water molecules, suggesting that ethanol replaces 15 additional water molecules upon MII formation. Amplification of ethanol effects on MII formation and acyl chain packing by osmolytes suggests that ethanol increases the equilibrium concentration of MII both by disordering acyl chain packing and by disrupting rhodopsin-water hydrogen bonds, demonstrating a direct effect of ethanol on rhodopsin. At physiologically relevant levels of osmolality and ethanol, about 90% of ethanol's effect is due to disordered acyl chain packing.
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Affiliation(s)
- D C Mitchell
- Section of Fluorescence Studies, Laboratory of Membrane Biophysics and Biochemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland 20853, USA
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40
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Yoshida T, Koga Y, Minowa H, Kamaya H, Ueda I. Interfacial Lateral Electrical Conductance on Lipid Monolayer: Dose-Dependent Converse Effect of Alcohols. J Phys Chem B 2000. [DOI: 10.1021/jp992715y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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Lee TH, Rivett D, Werkmeister J, Hewish D, Aguilar MI. Interaction of amphipathic peptides with an immobilised model membrane. ACTA ACUST UNITED AC 1999. [DOI: 10.1007/bf02443434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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42
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Trandum C, Westh P, Jørgensen K, Mouritsen OG. Association of ethanol with lipid membranes containing cholesterol, sphingomyelin and ganglioside: a titration calorimetry study. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1420:179-88. [PMID: 10446301 DOI: 10.1016/s0005-2736(99)00092-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The association of ethanol at physiologically relevant concentrations with lipid bilayers of different lipid composition has been investigated by use of isothermal titration calorimetry (ITC). The liposomes examined were composed of combinations of lipids commonly found in neural cell membranes: dimyristoyl phosphatidylcholine (DMPC), ganglioside (GM(1)), sphingomyelin and cholesterol. The calorimetric results show that the interaction of ethanol with fluid lipid bilayers is endothermic and strongly dependent on the lipid composition of the liposomes. The data have been used to estimate partitioning coefficients for ethanol into the fluid lipid bilayer phase and the results are discussed in terms of the thermodynamics of partitioning. The presence of 10 mol% sphingomyelin or ganglioside in DMPC liposomes enhances the partitioning coefficient by a factor of 3. Correspondingly, cholesterol (30 mol%) reduces the partitioning coefficient by a factor of 3. This connection between lipid composition and partitioning coefficient correlates with in vivo observations. Comparison of the data with the molecular structure of the lipid molecules suggests that ethanol partitioning is highly sensitive to changes in the lipid backbone (glycerol or ceramide) while it appears much less sensitive to the nature of the head group.
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Affiliation(s)
- C Trandum
- Department of Chemistry, Building 206, Technical University of Denmark, DK-2800, Lyngby, Denmark
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Ueda I, Yoshida T. Hydration of lipid membranes and the action mechanisms of anesthetics and alcohols. Chem Phys Lipids 1999; 101:65-79. [PMID: 10810926 DOI: 10.1016/s0009-3084(99)00056-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- I Ueda
- Department of Anesthesia, Department of Veterans Affairs Medical Center, University of Utah School of Medicine, Salt Lake City 84148, USA.
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44
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Abstract
Alcohol and water compete with each other on target membrane molecules, specifically, lipids and proteins near the membrane surface. The basis for this competition is the hydrogen bonding capability of both compounds. But alcohol's amphiphilic properties give it the capability to be attracted simultaneously to both hydrophobic and hydrophilic targets. Thus, alcohol could bind certain targets preferentially and displace water, leading to conformational consequences. This article reviews the clustering and organized character of biological water, which modulates the conformation of membrane surface molecules, particularly receptor protein. Any alcohol-induced displacement of biological water on or inside of membrane proteins creates the opportunity for allosteric change in membrane receptors. This interaction may also prevail in organelles, such as the Golgi apparatus, which have relatively low concentrations of bulk water. Target molecules of particular interest in neuronal membrane are zwitteronic phospholipids, gangliosides, and membrane proteins, including glycoproteins. FTIR and NMR spectroscopic evidence from model membrane systems shows that alcohol has a nonstereospecific binding capability for membrane surface molecules and that such binding occurs at sites that are otherwise occupied by hydrogen-bonded water. The significance of these effects seems to lie in the need to learn more about biological water as an active participant in biochemical actions. Proposed herein is a new working hypothesis that the molecular targets of ethanol action most deserving of study are those where water is trapped and there is little bulk water. Proteins (enzymes and receptors) certainly differ in this regard, as do organelles.
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Affiliation(s)
- W R Klemm
- Department Veterinary Anatomy & Public Health, Texas A&M University, College Station 77843, USA
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45
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Bearden AP, Gregory BW, Schultz TW. Growth kinetics of preexposed and naive populations of Tetrahymena pyriformis to 2-decanone and acetone. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 1997; 37:245-250. [PMID: 9378091 DOI: 10.1006/eesa.1997.1547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The growth kinetics of preexposed and naive Tetrahymena pyriformis grown in the presence of one hydrophilic and one hydrophobic nonpolar narcotic (acetone and 2-decanone, respectively) have been evaluated. The response of naive Tetrahymena exposed to nonpolar narcotics varied from a change in generation time upon exposure to hydrophilic chemical to a change in lag phase with similar generation time compared to control upon exposure to hydrophobic compounds. Tetrahymena grown in the presence of low concentrations of 2-decanone and then transferred to higher concentrations acclimated to the presence of the toxicant. Acclimation was demonstrated by reduced lag phases compared to naive cells. Results of population growth studies of Tetrahymena grown in the presence of low concentrations of acetone and then transferred to higher concentrations of acetone exhibit the same pattern, an increased generation time with increasing concentration with no lag time, as naive populations. Additionally, the observed generation times in acetone were cumulative relative to the transfer concentration as well as the acclimation concentration. The most feasible explanation for this phenomenon is the interaction of the toxicants with the plasma membrane.
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Affiliation(s)
- A P Bearden
- Graduate Program in Ecology and Evolutionary Biology, University of Tennessee, Knoxville 37901-1071, USA
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46
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Faure C, Bonakdar L, Dufourc EJ. Determination of DMPC hydration in the L(alpha) and L(beta') phases by 2H solid state NMR of D2O. FEBS Lett 1997; 405:263-6. [PMID: 9108301 DOI: 10.1016/s0014-5793(97)00201-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The number of water molecules bound to the dimyristoylphosphatidylcholine (DMPC) interface was investigated both in the fluid (L(alpha)) and gel (L(beta')) phases by solid state deuterium NMR of D2O. We determined that each DMPC molecule binds 9.7 +/- 0.5 and less than 4.3 +/- 0.5 D2O in the fluid and gel phases respectively. These results are accounted for by considering the number of DMPC binding sites as well as the molecular organization in each phase.
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Affiliation(s)
- C Faure
- Centre de Recherche Paul Pascal, CNRS, Pessac, France
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47
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Xu Y, Tang P. Amphiphilic sites for general anesthetic action? Evidence from 129Xe-[1H] intermolecular nuclear Overhauser effects. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1323:154-62. [PMID: 9030222 DOI: 10.1016/s0005-2736(96)00184-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Because a strong correlation exists between the potency of general anesthetics and their ability to dissolve in oil, a lipophilic site of action is often assumed. We show here that a lipophilic molecule may preferentially target less lipophilic sites after interaction with a membrane takes place. Xenon, a chemically inert and structureless general anesthetic, was chosen as an unbiased molecular probe for assessment of its dynamic distribution. Site-selective intermolecular 129Xe-[1H] nuclear Overhauser effects were used to measure the specific interaction between xenon and protons in different regions in a phosphatidylcholine lipid membrane. It was evident that xenon-membrane interaction was directed toward the amphiphilic head region, with significant involvement of interfacial water, despite xenon's apolar and highly lipophilic nature in the gas phase. This result may suggest the importance of amphiphilicity in association with anesthetic action.
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Affiliation(s)
- Y Xu
- Department of Anesthesiology and Critical Care Medicine, University of Pittsburgh, PA 15261, USA. xu2+@pitt.edu
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48
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Dibble AR, Hinderliter AK, Sando JJ, Biltonen RL. Lipid lateral heterogeneity in phosphatidylcholine/phosphatidylserine/diacylglycerol vesicles and its influence on protein kinase C activation. Biophys J 1996; 71:1877-90. [PMID: 8889163 PMCID: PMC1233655 DOI: 10.1016/s0006-3495(96)79387-6] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
To test the hypothesis that the activation of protein kinase C (PKC) is influenced by lateral heterogeneities of the components of the lipid bilayer, the thermotropic phase behavior of dimyristoylphosphatidylcholine (DMPC)/dimyristoylphosphatidylserine (DMPS)/dioleoylglycerol (DO) vesicles was compared with the activation of PKC by this system. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to monitor the main transition (i.e., the gel-to-fluid phase transition) as a function of mole fraction DO (chi(DO)) in DMPC/DO, DMPS/DO, and [DMPC/DMPS (1:1, mol/mol)]/DO multilamellar vesicles (MLVs). In each case, when chi(DO) < or approximately 0.3, DO significantly broadened the main transition and shifted it to lower temperatures; but when chi(DO) > approximately 0.3, the main transition became highly cooperative, i.e., narrow, again. The coexistence of overlapping narrow and broad transitions was clearly evident in DSC thermograms from chi(DO) approximately 0.1 to chi(DO) approximately 0.3, with the more cooperative transition growing at the expense of the broader one as chi(DO) increased. FTIR spectroscopy, using analogs of DMPC and DMPS with perdeuterated acyl chains, showed that the melting profiles of all three lipid components in [DMPC/DMPS (1:1, mol/mol)]/DO MLVs virtually overlay when chi(DO) = 0.33, suggesting that a new type of phase, with a phospholipid/DO mole ratio near 2:1, is formed in this system. Collectively, the results are consistent with the coexistence of DO-poor and DO-rich domains throughout the compositions chi(DO) approximately 0.1 to chi(DO) approximately 0.3, even at temperatures above the main transition. Comparison of the phase behavior of the binary mixtures with that of the ternary mixtures suggests that DMPS/DO interactions may be more favorable than DMPC/DO interactions in the ternary system, especially in the gel state. PKC activity was measured using [DMPC/DMPS (1:1, mol/mol)]/DO MLVs as the lipid activator. At 35 degrees C (a temperature above the main transition of the lipids), PKC activity increased gradually with increasing chi(DO) from chi(DO) approximately 0.1 to chi(DO) approximately 0.4, and activity remained high at higher DO contents. In contrast, at 2 degrees C (a temperature below the main transition), PKC activity exhibited a maximum between chi(DO) approximately 0.1 and chi(DO) approximately 0.3, and at higher DO contents activity was essentially constant at 20-25% of the activity at the maximum. We infer from these results that the formation of DO-rich domains is related to PKC activation, and when the lipid is in the gel state, the coexistence of DO-poor and DO-rich phases also contributes to PKC activation.
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Affiliation(s)
- A R Dibble
- Department of Pharmacology, University of Virginia Health Sciences Center, Charlottesville 22908, USA
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49
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Meyerhoff DJ, Rooney WD, Tokumitsu T, Weiner MW. Evidence of multiple ethanol pools in the brain: an in vivo proton magnetization transfer study. Alcohol Clin Exp Res 1996; 20:1283-8. [PMID: 8904983 DOI: 10.1111/j.1530-0277.1996.tb01124.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Studies of isolated cell membranes and animal brain extracts have shown that ethanol (EtOH) partitions into cell membranes. We tested the hypothesis that EtOH in the living brain after EtOH administration exists in two or more pools: a free, mobile pool of EtOH and one or more EtOH pools that are restricted in their molecular mobility, possibly because of association with membranes. In vivo brain proton magnetic resonance spectroscopy (1H MRS) routinely detects the methyl protons of the mobile EtOH pool but does not detect motionally restricted EtOH. We used in vivo brain 1H MRS in rat brain (n = 11) after intraperitoneal EtOH administration to measure the signal intensity of methyl EtOH protons in the presence and absence of off-resonance saturation. Off-resonance saturation resulted in a 33 +/- 4% decrease of the EtOH methyl proton signal. We interpret this signal reduction as a magnetization transfer effect. It is consistent with the existence of an MRS-invisible EtOH pool with restricted molecular mobility, which is in exchange with the free EtOH pool. Off-resonance saturation at the water frequency resulted in an even larger decrease of the EtOH methyl signal, consistent with water molecules being in close proximity to EtOH molecules at the restricted motion site(s). These results provide support for the hypothesis that partial MRS-invisibility of brain EtOH is at least to some extent caused by the presence of a (MRS-invisible) pool of motionally restricted EtOH. They also strongly suggest that water suppression, routinely used in in vivo 1H MRS, may reduce the observable EtOH methyl signal intensity through a magnetization transfer mechanism. These studies may provide both a mechanism of, and a means to investigate the alterations of EtOH MRS visibility observed in heavy drinkers.
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Affiliation(s)
- D J Meyerhoff
- Magnetic Resonance Unit, Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA
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50
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Wilkinson D, Ward JM, Woodley JM. Choice of microbial host for the naphthalene dioxygenase bioconversion. JOURNAL OF INDUSTRIAL MICROBIOLOGY 1996; 16:274-9. [PMID: 8757940 DOI: 10.1007/bf01570034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The use of whole cell biotransformations for single and multistep enzyme conversions is gaining widespread application. In this study the naphthalene dioxygenase nah A gene was transferred into Pseudomonas aeruginosa PAC 1R, Escherichia coli JM107 and Pseudomonas putida PpG 277. The effect of ethanol on these genetically engineered Gram-negative bacteria was studied by measurement of enzyme activity, stability and cell integrity. Ethanol has been used in biotransformations as a co-substrate carbon source for co-factor recycling and as a co-solvent increasing dissolved substrate and product levels. Ethanol increased the dissolved substrate (naphthalene) concentration slightly and dissolved product ((+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene) by approximately 30% at 4% (w/v) ethanol. Both P. aeruginosa PAC 1R and P. putida PpG 277 showed decreased activity with increasing ethanol concentration whilst E. coli enzyme activity increased with increasing ethanol concentration being comparable to that when glucose was used as a carbon source. This project highlighted the many factors involved in the selection of microbial hosts for whole cell biotransformation processes.
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Affiliation(s)
- D Wilkinson
- Department of Chemical and Biochemical Engineering, University College London, UK
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