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Kaur K, Singh A, Monga A, Mohana P, Khosla N, Bedi N. Antimicrobial and antibiofilm effects of shikonin with tea tree oil nanoemulsion against Candida albicans and Staphylococcus aureus. BIOFOULING 2023; 39:962-979. [PMID: 38009008 DOI: 10.1080/08927014.2023.2281511] [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: 05/08/2023] [Accepted: 11/04/2023] [Indexed: 11/28/2023]
Abstract
The current work aims to develop a shikonin and tea tree oil loaded nanoemulsion system stabilized by a mixture of GRAS grade surfactants (Tween 20 and monoolein) and a cosurfactant (Transcutol P). This system was designed to address the poor aqueous solubility and photostability issues of shikonin. The authenticity of shikonin employed in this study was confirmed using nuclear magnetic resonance (NMR) spectroscopy. The optimized nanoemulsion exhibited highly favorable characteristics in terms of zeta potential (-23.8 mV), polydispersity index (0.216) and particle size (22.97 nm). These findings were corroborated by transmission electron microscopy (TEM) micrographs which confirmed the spherical and uniform nature of the nanoemulsion globules. Moreover, attenuated total reflectance (ATR) and X-ray diffraction analysis (XRD) analysis affirmed improved chemical stability and amorphization, respectively. Photodegradation studies were performed by exposing pure shikonin and the developed nanoemulsion to ultraviolet light for 1 h using a UV lamp, followed by high performance liquid chromatography (HPLC) analysis. The results confirmed that the developed nanoemulsion system imparts photoprotection to pure shikonin in the encapsulated system. Furthermore, the research investigated the effect of the nanoemulsion on biofilms formed by Candida albicans and methicillin resistant Staphylococcus aureus (MRSA). Scanning electron microscopy, florescence microscopy and phase contrast microscopy unveiled a remarkable reduction in biofilm area, accompanied by disruptions in the cell wall and abnormalities on the cell surface of the tested microorganisms. In conclusion, the nanoencapsulation of shikonin with tea tree oil as the lipid phase showcased significantly enhanced antimicrobial and antibiofilm potential compared to pure shikonin against resistant strains of Candida albicans and Staphylococcus aureus.
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Affiliation(s)
- Kirandeep Kaur
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | - Atamjit Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | - Aditi Monga
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
| | - Pallvi Mohana
- Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, India
| | - Neha Khosla
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, India
| | - Neena Bedi
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, India
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Meikle TG, Keizer DW, Separovic F, Yao S. A solution NMR view of Lipidic Cubic Phases: Structure, dynamics, and beyond. BBA ADVANCES 2022; 2:100062. [PMID: 37082598 PMCID: PMC10074910 DOI: 10.1016/j.bbadva.2022.100062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/30/2022] [Accepted: 11/02/2022] [Indexed: 11/06/2022] Open
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is well-established nowadays for the elucidation of the 3D structures of proteins and protein complexes, the evaluation of biomolecular dynamics with atomistic resolution across a range of time scales, the screening of drug candidates with site specificity, and for the quantitation of molecular translational diffusion. Lyotropic lipidic cubic phases (LCPs) are lipid bilayer-based materials with a complex geometry, formed via the spontaneous self-assembly of certain lipids in an aqueous environment at specific temperature ranges. LCPs have been successfully applied to the in meso crystallization of membrane proteins for structural studies by X-ray crystallography, and have also shown promising potential for serving as matrices for drug and nutrient delivery/release in vivo. The characterization of the structural and dynamics properties of LCPs is of significant interest for the application of these materials. Here we present a systematic review detailing the characterization of LCPs by solution NMR. Using LCPs formed by monoolein (MO) as an example, various aspects of LCPs readily accessible by solution NMR are covered, including spectral perturbation in the presence of additives, quantification of hydration levels, 13C relaxation-based measurements for studying atom-specific dynamics along the MO hydrocarbon chain, PGSE NMR measurement of translational diffusion and its correlation with release profiles, and the encapsulation of soluble proteins in LCPs. A brief discussion of future perspectives for the characterization of LCPs by solution NMR is also presented.
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Meikle T, Keizer DW, Separovic F, Yao S. Water diffusion in complex systems measured by PGSE NMR using chemical shift selective stimulated echo: Elimination of magnetization exchange effects. J Chem Phys 2021; 155:224203. [PMID: 34911323 DOI: 10.1063/5.0073704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The interpretation of molecular translational diffusion as measured by pulsed gradient spin-echo NMR (PGSE NMR) can be complicated by the presence of chemical exchange and/or dipolar cross-relaxation (including relayed cross-relaxation via spin diffusion). The magnitude of influence depends on the kinetics of exchange and/or dipolar cross-relaxation present within the system as well as the PGSE NMR sequences chosen for measurements. First, we present an exchange induced zero-crossing phenomenon for signal attenuation of water in lipidic cubic phases (formed by a mixture of monoolein and water) in the presence of pulsed gradients observed using a standard STimulated Echo (STE) sequence. This magnetization exchange induced zero-crossing phenomenon, a pseudo-negative diffraction-like feature, resembles that reported previously for restricted diffusion when locally anisotropic pores are polydisperse or randomly oriented. We then demonstrate the elimination of these exchange and/or dipolar cross-relaxation induced effects with the use of a chemical shift selective STE (CHESS-STE) sequence, adapted from the previously reported band-selective short transient STE sequence, along with results obtained from the bipolar pulse pair STE sequence for comparison. The CHESS-STE sequence introduced here represents a generic form of PGSE NMR sequences for obtaining water diffusion coefficients free from the influence of exchange and/or dipolar cross-relaxation in complex systems. It has potential applications in measuring translational diffusion of water in biopolymer mixtures as well as probing the microscopic structure in materials via water restricted diffusion measured by PGSE NMR, particularly when the potential presence of exchange/cross-relaxation is of concern.
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Affiliation(s)
- Thomas Meikle
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, Victoria 3000, Australia
| | - David W Keizer
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Frances Separovic
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
| | - Shenggen Yao
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
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NMR spectroscopy of lipidic cubic phases. Biophys Rev 2021; 14:67-74. [DOI: 10.1007/s12551-021-00900-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/01/2021] [Indexed: 02/06/2023] Open
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Meikle TG, Keizer DW, Babon JJ, Drummond CJ, Separovic F, Conn CE, Yao S. Physiochemical Characterization and Stability of Lipidic Cubic Phases by Solution NMR. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6254-6260. [PMID: 32418433 DOI: 10.1021/acs.langmuir.0c00949] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lipidic inverse bicontinuous cubic phases (LCPs), formed via the spontaneous self-assembly of lipids such as monoolein, have found increasing applications in the stabilization and crystallization of integral membrane proteins for structural characterization using X-ray crystallography. Their use as effective drug release matrices has also been demonstrated. Nuclear magnetic resonance (NMR) spectroscopy, both solution and solid state, has previously been employed for the characterization of LCPs and related systems. Herein, we report a number of novel features of solution NMR for probing the fundamental composition and structural properties of monoolein-based LCPs. These include (1) more complete assignments of both 1H and 13C chemical shifts, (2) direct quantification of hydration level in LCPs using one-dimensional (1D) 1H NMR, and (3) monitoring longer-term stability of LCPs and evaluating alterations introduced into standard LCPs at the submolecular level.
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Affiliation(s)
- Thomas G Meikle
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - David W Keizer
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - Jeffrey J Babon
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, VIC 3010, Australia
| | - Calum J Drummond
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Frances Separovic
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
- School of Chemistry, The University of Melbourne, VIC 3010, Australia
| | - Charlotte E Conn
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Shenggen Yao
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
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Abraham A, Chan E, Park H. Fast understanding of phases and phase separation in liquid crystal drug delivery systems using deuterium solid-state NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2020; 106:101642. [PMID: 32035327 DOI: 10.1016/j.ssnmr.2020.101642] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/02/2020] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
Characterization of lipid based (SPC/GDO/H2O) liquid crystal (LC) drug delivery system is non-trivial and highly complex, especially when multiple and intermediate phases are present. The phase behavior of such mixtures during hydration or delivery is still poorly understood and therefore, characterizing these systems is crucially important towards controlling their function and enhancing the understanding of their drug release behavior. Current work has established an easy way to identify liquid crystal phases and phase mixtures using deuterium (2H) solid-state nuclear magnetic (NMR) spectroscopy under static conditions without disrupting the three dimensional structure and phases, as magic-angle spinning (MAS) could lead to disruption of the phases. Small angle X-ray scattering (SAXS) technique and optical microscopy were also employed to corroborate the study.
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Affiliation(s)
- Anuji Abraham
- Bristol-Myers Squibb, Materials Science and Engineering, Drug Product Science and Technology, New Brunswick, NJ, 08903, USA.
| | - Eric Chan
- Bristol-Myers Squibb, Materials Science and Engineering, Drug Product Science and Technology, New Brunswick, NJ, 08903, USA
| | - Hyunsoo Park
- Bristol-Myers Squibb, Materials Science and Engineering, Drug Product Science and Technology, New Brunswick, NJ, 08903, USA
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Meikle TG, Sethi A, Keizer DW, Babon JJ, Separovic F, Gooley PR, Conn CE, Yao S. Heteronuclear NMR spectroscopy of proteins encapsulated in cubic phase lipids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 305:146-151. [PMID: 31284168 DOI: 10.1016/j.jmr.2019.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/24/2019] [Accepted: 06/29/2019] [Indexed: 06/09/2023]
Abstract
Lipidic cubic phases, which form spontaneously via the self-assembly of certain lipids in an aqueous environment, are highly prospective nanomaterials with applications in membrane protein X-ray crystallography and drug delivery. Here we report 1H-15N heteronuclear single/multiple quantum coherence (HSQC, HMQC) spectra of 15N-enriched proteins encapsulated in inverse bicontinuous lipidic cubic phases obtained on a standard commercial high resolution NMR spectrometer at ambient temperature. 15N-enriched proteins encapsulated in this lipidic cubic phase show: (i) no significant changes in tertiary structure, (ii) significantly reduced solvent chemical exchange of backbone amides, which potentially provides a novel concept for quantifying residue-specific hydration; and (iii) improved spectral sensitivity achieved with band-selective excitation short-transient (BEST) spectroscopy, which is attributed to the presence of an abundant source of 1H nuclear spins originating from the lipid component of the cubic phase.
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Affiliation(s)
- Thomas G Meikle
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Ashish Sethi
- Department of Biochemistry & Molecular Biology, The University of Melbourne, VIC 3010, Australia; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - David W Keizer
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - Jeffrey J Babon
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia; School of Chemistry, The University of Melbourne, VIC 3010, Australia
| | - Paul R Gooley
- Department of Biochemistry & Molecular Biology, The University of Melbourne, VIC 3010, Australia; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia
| | - Charlotte E Conn
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia
| | - Shenggen Yao
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia.
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Meynaq MYK, Lindholm-Sethson B, Tesfalidet S. Interaction of anions with lipid cubic phase membranes, an electrochemical impedance study. J Colloid Interface Sci 2018; 528:263-270. [PMID: 29859451 DOI: 10.1016/j.jcis.2018.05.071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 11/30/2022]
Abstract
HYPOTHESIS Electrochemical impedance spectroscopy is useful to monitor anionic interactions with a Lipid Cubic Phase, as previously demonstrated for cationic interaction (Khani Meynaq et al., 2016). It was expected that the smaller hydrophilic anions, acetate and chloride, would interact differently than the large tryptophan anion with its hydrophobic tail. EXPERIMENT The impedance measurements enabled estimation of resistances and capacitances of a freestanding lipid cubic phase membrane at exposure to 4 and 40 mM solutions of NaCl, NaOAc and NaTrp. Small-angle X-ray scattering was used for cubic phase identification and to track structural changes within the cubic phase when exposed to the different electrolytes. FINDINGS The membrane resistance increases at exposure to the electrolytes in the order Cl- < OAc- < Trp-. The membrane resistance decreases with time at exposure to the hydrophilic anions and increases with time at Trp- exposure. The membrane capacitances were lower for NaTrp compared to NaCl and NaOAc at the corresponding concentrations which is consistent with the results from SAXRD. It is concluded that Trp- ions do not enter the aqueous channels of the cubic phase but are strongly adsorbed to the membrane/electrolyte interface leading to large alteration of the lipid phase structure and a high membrane resistance.
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Meikle T, Drummond C, Separovic F, Conn C. Membrane-Mimetic Inverse Bicontinuous Cubic Phase Systems for Encapsulation of Peptides and Proteins. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/bs.abl.2017.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Alawi MA, Hamdan II, Sallam ALSA, Heshmeh NA. Solubility enhancement of glibenclamide in choline–tryptophan ionic liquid: Preparation, characterization and mechanism of solubilization. J Mol Liq 2015. [DOI: 10.1016/j.molliq.2015.10.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Gater DL, Saurel O, Iordanov I, Liu W, Cherezov V, Milon A. Two classes of cholesterol binding sites for the β2AR revealed by thermostability and NMR. Biophys J 2015; 107:2305-12. [PMID: 25418299 DOI: 10.1016/j.bpj.2014.10.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/19/2014] [Accepted: 10/09/2014] [Indexed: 11/24/2022] Open
Abstract
Cholesterol binding to G protein-coupled receptors (GPCRs) and modulation of their activities in membranes is a fundamental issue for understanding their function. Despite the identification of cholesterol binding sites in high-resolution x-ray structures of the ?2 adrenergic receptor (β2AR) and other GPCRs, the binding affinity of cholesterol for this receptor and exchange rates between the free and bound cholesterol remain unknown. In this study we report the existence of two classes of cholesterol binding sites in β2AR. By analyzing the β2AR unfolding temperature in lipidic cubic phase (LCP) as a function of cholesterol concentration we observed high-affinity cooperative binding of cholesterol with sub-nM affinity constant. In contrast, saturation transfer difference (STD) NMR experiments revealed the existence of a second class of cholesterol binding sites, in fast exchange on the STD NMR timescale. Titration of the STD signal as a function of cholesterol concentration provided a lower limit of 100 mM for their dissociation constant. However, these binding sites are specific for both cholesterol and β2AR, as shown with control experiments using ergosterol and a control membrane protein (KpOmpA). We postulate that this specificity is mediated by the high-affinity bound cholesterol molecules and propose the formation of transient cholesterol clusters around the high-affinity binding sites.
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Affiliation(s)
- Deborah L Gater
- Institute of Pharmacology and Structural Biology - UMR 5089, CNRS and Université de Toulouse - UPS, 205 Route de Narbonne, 31077 Toulouse, France; Khalifa University of Science, Technology and Research, P.O. Box 127788, Abu Dhabi, UAE
| | - Olivier Saurel
- Institute of Pharmacology and Structural Biology - UMR 5089, CNRS and Université de Toulouse - UPS, 205 Route de Narbonne, 31077 Toulouse, France
| | - Iordan Iordanov
- Institute of Pharmacology and Structural Biology - UMR 5089, CNRS and Université de Toulouse - UPS, 205 Route de Narbonne, 31077 Toulouse, France
| | - Wei Liu
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, California
| | - Vadim Cherezov
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, California.
| | - Alain Milon
- Institute of Pharmacology and Structural Biology - UMR 5089, CNRS and Université de Toulouse - UPS, 205 Route de Narbonne, 31077 Toulouse, France.
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Gater DL, Réat V, Czaplicki G, Saurel O, Jolibois F, Cherezov V, Milon A. Hydrogen bonding of cholesterol in the lipidic cubic phase. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:8031-8038. [PMID: 23763339 PMCID: PMC3758441 DOI: 10.1021/la401351w] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The addition of cholesterol to the monoolein-based lipidic cubic phase (LCP) has been instrumental in obtaining high-resolution crystal structures of several G protein-coupled receptors. Here, we report the use of high-resolution magic angle spinning NMR spectroscopy to record and assign the isotropic (13)C chemical shifts of cholesterol in lipidic lamellar and cubic phases at different hydration levels with monoolein and chain-deuterated DMPC as host lipids. The hydrogen-bonding patterns of cholesterol in these phases were determined from the NMR data by quantum chemical calculations. The results are consistent with the normal orientation of cholesterol in lipid bilayers and with the cholesterol hydroxyl group located at the hydrophobic/hydrophilic interface. The (13)C chemical shifts of cholesterol are mostly affected by the host lipid identity with little or no dependency on the hydration (20% vs 40%) or the phase identity (lamellar vs LCP). In chain-deuterated DMPC bilayers, the hydroxyl group of cholesterol forms most of its hydrogen bonds with water, while in monoolein bilayers it predominately interacts with monoolein. Such differences in the hydrogen-bonding network of cholesterol may have implications for the design of experiments in monoolein-based LCP.
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Affiliation(s)
- Deborah L. Gater
- Institut de Pharmacologie et de Biologie Structurale, UMR 5089 CNRS - Université de Toulouse, UPS, BP 64182, 205 route de Narbonne, 31077 Toulouse Cedex04 (France)
| | - Valérie Réat
- Institut de Pharmacologie et de Biologie Structurale, UMR 5089 CNRS - Université de Toulouse, UPS, BP 64182, 205 route de Narbonne, 31077 Toulouse Cedex04 (France)
| | - Georges Czaplicki
- Institut de Pharmacologie et de Biologie Structurale, UMR 5089 CNRS - Université de Toulouse, UPS, BP 64182, 205 route de Narbonne, 31077 Toulouse Cedex04 (France)
| | - Olivier Saurel
- Institut de Pharmacologie et de Biologie Structurale, UMR 5089 CNRS - Université de Toulouse, UPS, BP 64182, 205 route de Narbonne, 31077 Toulouse Cedex04 (France)
| | - Franck Jolibois
- Laboratoire de Physique et Chimie des Nano Objets, UMR 5215, IRSAMC -Université de Toulouse, UPS, 135 Avenue de Rangueil, 31077 Toulouse Cedex04 (France)
| | - Vadim Cherezov
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla CA 92037 (USA)
| | - Alain Milon
- Institut de Pharmacologie et de Biologie Structurale, UMR 5089 CNRS - Université de Toulouse, UPS, BP 64182, 205 route de Narbonne, 31077 Toulouse Cedex04 (France)
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Recent Developments in the Production, Analysis, and Applications of Cubic Phases Formed by Lipids. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-12-411515-6.00006-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Warschawski DE, Arnold AA, Beaugrand M, Gravel A, Chartrand É, Marcotte I. Choosing membrane mimetics for NMR structural studies of transmembrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1957-74. [DOI: 10.1016/j.bbamem.2011.03.016] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 03/28/2011] [Accepted: 03/29/2011] [Indexed: 12/11/2022]
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Kulkarni CV, Wachter W, Iglesias-Salto G, Engelskirchen S, Ahualli S. Monoolein: a magic lipid? Phys Chem Chem Phys 2011; 13:3004-21. [DOI: 10.1039/c0cp01539c] [Citation(s) in RCA: 295] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Momot KI, Takegoshi K, Kuchel PW, Larkin TJ. Inhomogeneous NMR line shape as a probe of microscopic organization of bicontinuous cubic phases. J Phys Chem B 2008; 112:6636-45. [PMID: 18457445 DOI: 10.1021/jp8006415] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NMR line shapes of the lipid and aqueous species in bicontinuous cubic phase (BCP) samples prepared by centrifugation are inhomogeneously broadened. The broadening of the lipid peaks is removed by magic-angle spinning (MAS). In this work, we studied the mechanism of this broadening using (1)H and (13)C NMR spectroscopy of a myverol/water BCP. It is demonstrated that the inhomogeneity possesses an intrinsic contribution that is independent of instrumental or setup factors and can be attributed to the microscopic organization of the BCP bilayer. A mechanism of the inhomogeneous broadening is proposed, which involves a spatially nonuniform diamagnetically induced magnetic field determined by the mesoscopic structure and the diamagnetic susceptibilities of the two BCP domains. The proposed mechanism does not require that molecular reorientation of the lipid be slow for the inhomogeneous broadening to survive. We discuss how this inhomogeneous broadening can be employed as a probe of compositional uniformity and microscopic organization of BCP samples.
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Affiliation(s)
- Konstantin I Momot
- School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Qld 4001, Australia.
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