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Nathan L, Daniel S. Single Virion Tracking Microscopy for the Study of Virus Entry Processes in Live Cells and Biomimetic Platforms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1215:13-43. [PMID: 31317494 PMCID: PMC7122913 DOI: 10.1007/978-3-030-14741-9_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The most widely-used assays for studying viral entry, including infectivity, cofloatation, and cell-cell fusion assays, yield functional information but provide low resolution of individual entry steps. Structural characterization provides high-resolution conformational information, but on its own is unable to address the functional significance of these conformations. Single virion tracking microscopy techniques provide more detail on the intermediate entry steps than infection assays and more functional information than structural methods, bridging the gap between these methods. In addition, single virion approaches also provide dynamic information about the kinetics of entry processes. This chapter reviews single virion tracking techniques and describes how they can be applied to study specific virus entry steps. These techniques provide information complementary to traditional ensemble approaches. Single virion techniques may either probe virion behavior in live cells or in biomimetic platforms. Synthesizing information from ensemble, structural, and single virion techniques ultimately yields a more complete understanding of the viral entry process than can be achieved by any single method alone.
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Affiliation(s)
- Lakshmi Nathan
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
| | - Susan Daniel
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
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Stefaniu C, Ries A, Gutowski O, Ruett U, Seeberger PH, Werz DB, Brezesinski G. Impact of Structural Differences in Galactocerebrosides on the Behavior of 2D Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:2436-2444. [PMID: 26907993 DOI: 10.1021/acs.langmuir.5b03830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The molecular interactions of three biologically important galactocerebrosides have been studied in monolayers formed at the soft air/water interface as 2D model membranes. Highly surface-sensitive techniques as GIXD (grazing incidence X-ray diffraction), IRRAS (infrared reflection-absorption spectroscopy), and BAM (Brewster angle microscopy) have been used. The study reveals that small differences in the chemical structure have a relevant impact on the physical-chemical properties and intermolecular interactions. The presence of a 2-d-hydroxyl group in the fatty acid favored for GalCer C24:0 (2-OH) monolayers a higher hydration state of the headgroup at low lateral pressures (<25 mN/m) and a higher condensation effect above 30 mN/m. An opposite behavior was recorded for GalCer C24:0 and GalCer C24:1, for which the intermolecular interactions are defined by the weakly hydrated but strong H-bonded interconnected head groups. Additionally, the 15-cis-double bond in the fatty acid chain (nervonic acid) of GalCer C24:1 stabilized the LE phase but did not disturb the packing parameters of the LC phase as compared with the saturated compound GalCer C24:0.
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Affiliation(s)
- Cristina Stefaniu
- Max Planck Institute of Colloids and Interfaces , Science Park Potsdam-Golm, 14476 Potsdam, Germany
| | - Annika Ries
- Georg-August-Universität Göttingen , Institute of Organic and Biomolecular Chemistry, Tammannstr. 2, 37077 Göttingen, Germany
| | - Olof Gutowski
- DESY , Forschungsbereich FS, Notkestr. 85, 22603 Hamburg, Germany
| | - Uta Ruett
- DESY , Forschungsbereich FS, Notkestr. 85, 22603 Hamburg, Germany
| | - Peter H Seeberger
- Max Planck Institute of Colloids and Interfaces , Science Park Potsdam-Golm, 14476 Potsdam, Germany
- Freie Universität Berlin , Institute of Chemistry and Biochemistry, Arnimallee 22, 14195 Berlin, Germany
| | - Daniel B Werz
- Technische Universität Braunschweig , Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany
| | - Gerald Brezesinski
- Max Planck Institute of Colloids and Interfaces , Science Park Potsdam-Golm, 14476 Potsdam, Germany
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Vaccine-induced HIV-1 envelope gp120 constant region 1-specific antibodies expose a CD4-inducible epitope and block the interaction of HIV-1 gp140 with galactosylceramide. J Virol 2014; 88:9406-17. [PMID: 24920809 DOI: 10.1128/jvi.01031-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Mucosal epithelial cell surface galactosylceramide (Galcer) has been postulated to be a receptor for HIV-1 envelope (Env) interactions with mucosal epithelial cells. Disruption of the HIV-1 Env interaction with such alternate receptors could be one strategy to prevent HIV-1 entry through the mucosal barrier. To study antibody modulation of HIV-1 Env-Galcer interactions, we used Galcer-containing liposomes to assess whether natural- and vaccine-induced monoclonal antibodies can block HIV-1 Env binding to Galcer. HIV-1 Env gp140 proteins bound to Galcer liposomes with Kds (dissociation constants) in the nanomolar range. Several HIV-1 ALVAC/AIDSVAX vaccinee-derived monoclonal antibodies (MAbs) specific for the gp120 first constant (C1) region blocked Galcer binding of a transmitted/founder HIV-1 Env gp140. Among the C1-specific MAbs that showed Galcer blocking, the antibody-dependent cellular cytotoxicity-mediating CH38 IgG and its natural IgA isotype were the most potent blocking antibodies. C1-specific IgG monoclonal antibodies that blocked Env binding to Galcer induced upregulation of the gp120 CD4-inducible (CD4i) epitope bound by MAb 17B, demonstrating that a conformational change in gp120 may be required for Galcer blocking. However, the MAb 17B itself did not block Env-Galcer binding, suggesting that the C1 antibody-induced gp120 conformational changes resulted in alteration in a Galcer binding site distant from the CD4i 17B MAb binding site. IMPORTANCE Galactosyl ceramide, a glycosphingolipid, has been postulated to be a receptor for the HIV-1 envelope glycoprotein (Env) interaction with mucosal epithelial cells. Here, we have mimicked this interaction by using an artificial membrane containing synthetic Galcer and recombinant HIV-1 Env proteins to identify antibodies that would block the HIV-1 Env-Galcer interaction. Our study revealed that a class of vaccine-induced human antibodies potently blocks HIV-1 Env-Galcer binding by perturbing the HIV-1 Env conformation.
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Gutman J, Kaufman Y, Kawahara K, Walker SL, Freger V, Herzberg M. Interactions of glycosphingolipids and lipopolysaccharides with silica and polyamide surfaces: adsorption and viscoelastic properties. Biomacromolecules 2014; 15:2128-37. [PMID: 24835578 DOI: 10.1021/bm500245z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Bacterial outer membrane components play a critical role in bacteria-surface interactions (adhesion and repulsion). Sphingomonas species (spp.) differ from other Gram-negative bacteria in that they lack lipopolysaccharides (LPSs) in their outer membrane. Instead, Sphingomonas spp. outer membrane consists of glycosphingolipids (GSLs). To delineate the properties of the outer membrane of Sphingomonas spp. and to explain the adhesion of these cells to surfaces, we employed a single-component-based approach of comparing GSL vesicles to LPS vesicles. This is the first study to report the formation of vesicles containing 100% GSL. Significant physicochemical differences between GSL and LPS vesicles are reported. Composition-dependent vesicle adherence to different surfaces using quartz crystal microbalance with dissipation monitoring (QCM-D) technology was observed, where higher GSL content resulted in higher mass accumulation on the sensor. Additionally, the presence of 10% GSL and above was found to promote the relative rigidity of the vesicle obtaining viscoelastic ratio of 30-70% higher than that of pure LPS vesicles.
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Affiliation(s)
- Jenia Gutman
- Department of Desalination and Water Treatment, Zuckerberg Institute for Water Research, Albert Katz International School for Desert Studies, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev , Sede-Boqer Campus, Midreshet Ben Gurion 84990, Israel
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Thota VN, Brahmaiah M, Kulkarni SS. Synthesis of a C-Glycoside Analogue of β-Galactosyl Ceramide, a Potential HIV-1 Entry Inhibitor. J Org Chem 2013; 78:12082-9. [DOI: 10.1021/jo402115w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- V. Narasimharao Thota
- Department
of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Mula Brahmaiah
- Department
of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Suvarn S. Kulkarni
- Department
of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
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Bally M, Rydell GE, Zahn R, Nasir W, Eggeling C, Breimer ME, Svensson L, Höök F, Larson G. Norovirus GII.4 Virus-like Particles Recognize Galactosylceramides in Domains of Planar Supported Lipid Bilayers. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bally M, Rydell GE, Zahn R, Nasir W, Eggeling C, Breimer ME, Svensson L, Höök F, Larson G. Norovirus GII.4 virus-like particles recognize galactosylceramides in domains of planar supported lipid bilayers. Angew Chem Int Ed Engl 2012; 51:12020-4. [PMID: 23097253 PMCID: PMC3546384 DOI: 10.1002/anie.201205972] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Indexed: 01/13/2023]
Affiliation(s)
- Marta Bally
- Department of Applied Physics, Chalmers University of TechnologySE-41133 Göteborg (Sweden)
| | - Gustaf E Rydell
- Traffic, Signaling, and Delivery Laboratory, Centre de Recherche, Institut CurieCNRS UMR144 (France)
| | - Raphael Zahn
- Laboratory of Biosensors and Bioelectronics, Institute of Biomedical Engineering, Universität Zürich und ETH Zürich(Switzerland)
| | - Waqas Nasir
- Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy, University of Gothenburg(Sweden)
| | - Christian Eggeling
- Department of Applied Physics, Chalmers University of TechnologySE-41133 Göteborg (Sweden)
| | - Michael E Breimer
- Department of Surgery, Sahlgrenska Academy, University of Gothenburg(Sweden)
| | | | - Fredrik Höök
- Department of Applied Physics, Chalmers University of TechnologySE-41133 Göteborg (Sweden)
| | - Göran Larson
- Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy, University of Gothenburg(Sweden)
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Bachan S, Fantini J, Joshi A, Garg H, Mootoo DR. Synthesis, gp120 binding and anti-HIV activity of fatty acid esters of 1,1-linked disaccharides. Bioorg Med Chem 2011; 19:4803-11. [PMID: 21783371 DOI: 10.1016/j.bmc.2011.06.078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 06/22/2011] [Accepted: 06/27/2011] [Indexed: 11/19/2022]
Abstract
Inspired by the anti-human immunodeficiency virus (HIV) activity of analogues of β-galactosylceramide (GalCer), a set of mono- and di-saccharide fatty acid esters were designed as GalCer mimetics and their binding to the V3 loop peptide of HIV-1 and anti-HIV activity evaluated. 1,1-linked Gal-Man and Glu-Man disaccharides with an ester on the Man subunit bound the V3 loop peptide and inhibited HIV infectivity in single round infection assays with the TZM-bl cell line. IC(50)'s were in the 50 μM range with no toxicity to the cells at concentrations up to 200 μM. These compounds appear to inhibit virus entry at early steps in viral infection since they were inactive if added post viral entry. Although these compounds were found to bind to the V3 loop peptide of gp120, it is not clear that this interaction is responsible for their anti-HIV activity because the relative binding affinity of closely related analogues did not correlate with their antiviral behavior. The low cytotoxicity of these 1,1-linked disaccharide fatty acid esters, combined with the easy accessibility to structurally diverse analogues make these molecules attractive leads for new topical anti-viral agents.
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Affiliation(s)
- Stewart Bachan
- Department of Chemistry, Hunter College, 695 Park Avenue, New York, NY 10021, USA
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9
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Dynamic Nanoplatforms in Biosensor and Membrane Constitutional Systems. CONSTITUTIONAL DYNAMIC CHEMISTRY 2011; 322:139-63. [DOI: 10.1007/128_2011_199] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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10
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Nanoscale Techniques for Biomarker Quantification. Biomarkers 2010. [DOI: 10.1002/9780470918562.ch18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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Urbano J, Korthals B, Díaz-Requejo MM, Pérez PJ, Mecking S. Catalytic cyclopropanation of polybutadienes. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/pola.24231] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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12
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Morales-Serna JA, Boutureira O, Serra A, Matheu MI, Díaz Y, Castillón S. Synthesis of Hyperbranched β-Galceramide-Containing Dendritic Polymers that Bind HIV-1 rgp120. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000132] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Sui Z, Hanan NJ, Phimphivong S, Wysocki RJ, Saavedra SS. Synthesis, characterization and sol-gel entrapment of a crown ether-styryl fluoroionophore. LUMINESCENCE 2009; 24:236-42. [PMID: 19253273 DOI: 10.1002/bio.1106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The synthesis and initial evaluation of a new dye-functionalized crown-ether, 2-[2-(2,3,5,6,8,9,11,12,14,15-decahydro-1,4,7,10,13,16-benzohexaoxacyclooctadecin)ethenyl]-3-methyl benzothiazolium iodide (denoted BSD), are reported. This molecule contains a benzyl 18-crown-6 moiety as the ionophore and a benzothiazolium to spectrally transduce ion binding. Binding of K(+) to BSD in methanol causes shifts in the both absorbance and fluorescence emission maxima, as well as changes in the molar absorptivity and the emission intensity. Apparent dissociation constants (K(d)) in the range 30-65 microm were measured. In water and neutral buffer, K(d) values were approximately 1 mm. BSD was entrapped in sol-gel films composed of methyltriethoxysilane (MTES) and tetraethylorthosilicate (TEOS) with retention of its spectral properties and minimal leaching. K(+) binding to BSD in sol-gel films immersed in pH 7.4 buffer causes significant fluorescence quenching, with an apparent response time of approximately 2 min and an apparent K(d) of 1.5 mm.
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Affiliation(s)
- Zhijie Sui
- Department of Chemistry, The University of Arizona, Tucson, AZ 85721, USA
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15
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Subramaniam V, D'Ambruoso GD, Hall HK, Wysocki RJ, Brown MF, Saavedra SS. Reconstitution of rhodopsin into polymerizable planar supported lipid bilayers: influence of dienoyl monomer structure on photoactivation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:11067-75. [PMID: 18759470 PMCID: PMC2726791 DOI: 10.1021/la801835g] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
G-protein-coupled receptors (GPCRs) play key roles in cellular signal transduction and many are pharmacologically important targets for drug discovery. GPCRs can be reconstituted in planar supported lipid bilayers (PSLBs) with retention of activity, which has led to development of GPCR-based biosensors and biochips. However, PSLBs composed of natural lipids lack the high stability desired for many technological applications. One strategy is to use synthetic lipid monomers that can be polymerized to form robust bilayers. A key question is how lipid polymerization affects GPCR structure and activity. Here we have investigated the photochemical activity of bovine rhodopsin (Rho), a model GPCR, reconstituted into PSLBs composed of lipids having one or two polymerizable dienoyl moieties located in different regions of the acyl chains. Plasmon waveguide resonance spectroscopy was used to compare the degree of Rho photoactivation in fluid and poly(lipid) PSLBs. The position of the dienoyl moiety was found to have a significant effect: polymerization near the glycerol backbone significantly attenuates Rho activity whereas polymerization near the acyl chain termini does not. Differences in cross-link density near the acyl chain termini also do not affect Rho activity. In unpolymerized PSLBs, an equimolar mixture of phosphatidylethanolamine and phosphatidylcholine (PC) lipids enhances activity relative to pure PC; however after polymerization, the enhancement is eliminated which is attributed to stabilization of the membrane lamellar phase. These results should provide guidance for the design of robust lipid bilayers functionalized with transmembrane proteins for use in membrane-based biochips and biosensors.
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Affiliation(s)
- Varuni Subramaniam
- Department of Chemistry, University of Arizona, Tucson, Arizona, 85721-0041
| | | | - H. K. Hall
- Department of Chemistry, University of Arizona, Tucson, Arizona, 85721-0041
| | - Ronald J. Wysocki
- Department of Chemistry, University of Arizona, Tucson, Arizona, 85721-0041
| | - Michael F. Brown
- Department of Chemistry, University of Arizona, Tucson, Arizona, 85721-0041
| | - S. Scott Saavedra
- Department of Chemistry, University of Arizona, Tucson, Arizona, 85721-0041
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Anglin TC, Conboy JC. Lateral pressure dependence of the phospholipid transmembrane diffusion rate in planar-supported lipid bilayers. Biophys J 2008; 95:186-93. [PMID: 18339755 PMCID: PMC2426632 DOI: 10.1529/biophysj.107.118976] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 12/31/2007] [Indexed: 11/18/2022] Open
Abstract
The dependence of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) flip-flop kinetics on the lateral membrane pressure in a phospholipid bilayer was investigated by sum-frequency vibrational spectroscopy. Planar-supported lipid bilayers were prepared on fused silica supports using the Langmuir-Blodgett/Langmuir-Schaeffer technique, which allows precise control over the lateral surface pressure and packing density of the membrane. The lipid bilayer deposition pressure was varied from 28 to 42 mN/m. The kinetics of lipid flip-flop in these membranes was measured by sum-frequency vibrational spectroscopy at 37 degrees C. An order-of-magnitude difference in the rate constant for lipid translocation (10.9 x 10(-4) s(-1) to 1.03 x 10(-4) s(-1)) was measured for membranes prepared at 28 mN/m and 42 mN/m, respectively. This change in rate results from only a 7.4% change in the packing density of the lipids in the bilayer. From the observed kinetics, the area of activation for native phospholipid flip-flop in a protein-free DPPC planar-supported lipid bilayer was determined to be 73 +/- 12 A(2)/molecule at 37 degrees C. Significance of the observed activation area and potential future applications of the technique to the study of phospholipid flip-flop are discussed.
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Affiliation(s)
- Timothy C Anglin
- Department of Chemistry, University of Utah, Salt Lake City, Utah, USA
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Velarde TRC, Wirth MJ. Silica colloidal crystals as porous substrates for total internal reflection fluorescence microscopy of live cells. APPLIED SPECTROSCOPY 2008; 62:611-616. [PMID: 18559147 DOI: 10.1366/000370208784657986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Total internal reflection fluorescence (TIRF) microscopy is a powerful means of probing biological cells because it reduces autofluorescence, but the need for direct contact between the cell surface and the microscope slide hinders chemical access to the cell surface. In this work, a submicrometer crystalline layer of colloidal silica on the microscope coverslip is shown to allow TIRF microscopy while also allowing chemical access to the cell surface. A 750 nm layer of 165 nm silica colloidal crystals was sintered onto a fused silica coverslip, and Chinese hamster ovary cells were successfully grown on this surface. This cell line over-expresses the human delta-opioid receptor, which enabled probing of the binding of a labeled ligand to the receptors on the cell surface. Total internal reflection and chemical access to the cell surface are demonstrated. The range of angles for total internal reflection is reduced only by 1/3 due to the lower index of refraction of the colloidal multilayer relative to fused silica.
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Affiliation(s)
- Tomika R C Velarde
- Department of Chemistry, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721, USA
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18
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Imura T, Masuda Y, Ito S, Worakitkanchanakul W, Morita T, Fukuoka T, Sakai H, Abe M, Kitamoto D. Packing Density of Glycolipid Biosurfactant Monolayers Give a Significant Effect on Their Binding Affinity Toward Immunoglobulin G. J Oleo Sci 2008; 57:415-22. [DOI: 10.5650/jos.57.415] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Domain nucleation rates and interfacial line tensions in supported bilayers of ternary mixtures containing galactosylceramide. Biophys J 2007; 94:2691-7. [PMID: 18065459 DOI: 10.1529/biophysj.107.122572] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Domains within the plane of the plasma membrane, referred to as membrane rafts, have been a topic of considerable interest in the field of membrane biophysics. Although model membrane systems have been used extensively to study lipid phase behavior as it relates to the existence of rafts, very little work has focused on either the initial stage of lipid domain nucleation, or the relevant physical parameters such as temperature and interfacial line tension which control nucleation. In this work, we utilize a method in which the kinetic process of lipid domain nucleation is imaged by atomic force microscopy and modeled using classical theory of nucleation to map interfacial line tension in ternary lipid mixtures. These mixtures consist of a fluid phase lipid component (1,2-dilauroyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, or 1,2-dioleoyl-sn-glycero-3-phosphocholine), a solid phase component (galactosylceramide), and cholesterol. Interfacial line tension measurements of galactosylceramide-rich domains track with our previously measured area/perimeter ratios and height mismatches measured here. Line tension also follows known trends in cholesterol interactions and partitioning, as we observed previously with area/perimeter ratios. Our line tension measurements are discussed in combination with recent line tension measurements to address line tension regulation by cholesterol and the dynamic nature of membrane rafts.
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20
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Longo GS, Thompson DH, Szleifer I. Stability and phase separation in mixed monopolar lipid/bolalipid layers. Biophys J 2007; 93:2609-21. [PMID: 17573422 PMCID: PMC1989698 DOI: 10.1529/biophysj.106.102764] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Accepted: 06/04/2007] [Indexed: 11/18/2022] Open
Abstract
The phase stability of a fluid lipid layer that is a mixture of conventional monopolar lipids and C20 bipolar bolalipids was studied using a mean field theory that explicitly includes molecular details and configurational properties of the lipid molecules. The effect of changing the fraction of bolalipids, as well as the length of the hydrocarbon chain of the monopolar lipids, was probed. A phase separation between two liquid lipid phases was found when a mismatch exists in the optimal hydrophobic thicknesses of the pure bolalipid and monopolar lipid layers. The lipid mixture phase separates into a thin bolalipid-rich layer and a thicker monopolar-rich layer. The thin membrane phase is mainly composed of transmembrane bolalipid molecules whose polar heads are positioned at opposite membrane-water interfaces. In the monopolar lipid-rich phase, bolalipids are the minor component and most of them assume a looping configuration where both headgroups are present at the same membrane-water interface. For mixed layers that form a single lipid phase across all bolalipid concentrations, the hairpin-transmembrane ratio strongly depends on the hydrocarbon chain length of the monopolar lipid and the bolalipid concentration. The C-D bond order parameters of the different species have been calculated. Our findings suggest that the concentration-dependent phase transition should be experimentally observable by measuring of the order parameters through quadrupolar splitting experiments. The driving force for the phase separation in the monopolar lipid/bolalipid mixture is the packing mismatch between hydrophobic regions of the monopolar lipid hydrocarbon chains and the membrane-spanning bolalipid chains. The results from the molecular theory may be useful in the design of stable lipid layers for integral membrane protein sensing.
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Affiliation(s)
- Gabriel S Longo
- Department of Chemistry, Purdue University, West Lafayette, Indiana, USA
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McReynolds KD, Gervay-Hague J. Chemotherapeutic Interventions Targeting HIV Interactions with Host-Associated Carbohydrates. Chem Rev 2007; 107:1533-52. [PMID: 17439183 DOI: 10.1021/cr0502652] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Katherine D McReynolds
- Department of Chemistry, California State University, Sacramento, Sacramento, California 95819, USA.
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Johnson HR, Hooker JM, Francis MB, Clark DS. Solubilization and stabilization of bacteriophage MS2 in organic solvents. Biotechnol Bioeng 2007; 97:224-34. [PMID: 17099911 DOI: 10.1002/bit.21245] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Several techniques were examined for the solubilization of bacteriophage MS2 in organic solvents. Direct extraction of the MS2 from an aqueous phase into isooctane containing 2 mM AOT, a proven approach for the organic solubilization of many proteins, was not successful. However, predried samples of MS2 were solubilized through the direct addition of organic solvents containing 500 mM AOT. As an alternative procedure, reverse micelles containing aqueous solutions of MS2 were prepared in isooctane using AOT, dehydrated through solvent evaporation and azeotropic drying, and resolubilized in a solvent of choice. The structure and microenvironment of organic-solubilized MS2 were investigated by UV absorbance, the fluorescence emission of an attached solvatochromatic dye, tryptophan fluorescence, and atomic force microscopy, all of which contributed evidence for a fully assembled capsid in the organic solvent. The solubilized MS2 was derivatized with stearic acid in chloroform, illustrating that bioconjugation reactions can be performed on organic-solubilized capsids using reagents that are completely insoluble in water. Furthermore, the organic-solubilized phage remained infectious after heating at 90 degrees C for 20 min, whereas phage in aqueous buffer or dried with nitrogen were nonviable following the heat treatment protocol. The extended range of available chemical modifications and the enhanced thermal stability of the organic-solubilized capsids bodes well for the formulation of storage-stable vaccines predicated on reactions in or exposure to organic media.
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Affiliation(s)
- Harvey R Johnson
- Department of Chemical Engineering, University of California, Berkeley, California 94720, USA
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23
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Masaoka S, Tanaka D, Kitahata H, Araki S, Matsuda R, Yoshikawa K, Kato K, Takata M, Kitagawa S. Chemical Reaction-Inspired Crystal Growth of a Coordination Polymer toward Morphology Design and Control. J Am Chem Soc 2006; 128:15799-808. [PMID: 17147390 DOI: 10.1021/ja065254k] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper reports a novel crystal growth system of a coordination framework {[Cu3(CN)3{hat-(CN)3(OEt)3}]}n (1) (hat-(CN)3(OEt)3 = 2,6,10-tricyano-3,7,11-triethoxy-1,4,5,8,9,12-hexaazatriphenylene). The coordination polymer is crystallized through the reaction of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (hat-(CN)6), ethanol, and copper(I) complex, involving the breaking and forming of covalent bonds. The crystal morphologies obtained in the present system contain dumbbells, cogwheels, and superlattices. Moreover, in the growth perpendicular to the c-axis, periodic ramification at regular interval is observed, affording superlattice morphologies. Observation of the growth of dumbbell crystals shows that the growth rates parallel and perpendicular to the crystallographic c-axis are quite different: the former shows a drastic change with the reaction duration, while the latter is almost constant. These results are reproduced as a simple reaction-diffusion system, indicating that chemical reactions on crystal surfaces play an important role in determining the macroscopic crystal morphologies.
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Affiliation(s)
- Shigeyuki Masaoka
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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24
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Lim KI, Yin J. Dynamic tradeoffs in the raft-mediated entry of human immunodeficiency virus type 1 into cells. Biotechnol Bioeng 2006; 93:246-57. [PMID: 16136590 DOI: 10.1002/bit.20680] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
To initiate an infection human immunodeficiency virus type 1 (HIV-1) particles must first bind to receptors on the surface of their host cells, a process that eventually leads to fusion of viral and cellular membranes and release of the viral genome into the cytoplasm. Understanding the molecular mechanisms of these processes may enable the development of new anti-HIV strategies. Disagreement currently prevails on the role in virus entry of microdomains within the cellular plasma membrane known as lipid rafts. Experiments have suggested that lipid rafts, in their interactions with cellular receptors and viral particles, either promote or have minimal effect on viral entry. Here we develop a dynamic model for HIV-1 entry that enables us to identify and quantitatively assess tradeoffs that can arise from the clustering of receptors in rafts. Specifically, receptor clustering can be detrimental to the initiation of viral infection by reducing the probability that a virus particle finds its primary receptor, CD4. However, receptor clustering can also enable a virus particle, once bound, to rapidly form multivalent interactions with receptors and co-receptors that are required for virus-cell membrane fusion. We show how the resolution of such tradeoffs hinges on the level and spatial distribution of receptors and co-receptors on the cell surface, and we discuss implications of these effects for the design of therapeutics that inhibit HIV-1 entry.
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Affiliation(s)
- Kwang-il Lim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1607, USA
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25
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Abstract
As a result of heterogeneous spreading of distinct lipids within the same microspots of air-stable lipid microarrays, ganglioside GM1 tends to segregate and thus enrich within the center area of microspots where being predetermined by the quill pin used for array fabrication, as indicated by the binding pattern of fluorescein-cholera toxin subunit B.
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Affiliation(s)
- Ye Fang
- Biochemical Technologies, Science and Technology Division, Corning Inc., Sullivan Park, New York 14831, USA
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26
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Lam SN, Gervay-Hague J. Efficient synthesis of Man2, Man3, and Man5 oligosaccharides, using mannosyl iodide donors. J Org Chem 2005; 70:8772-9. [PMID: 16238308 PMCID: PMC2519013 DOI: 10.1021/jo051360d] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] A highly efficient protocol for making Man(3) and Man(5) oligosaccharides with use of orthogonally protected glycosyl iodide donors has been developed. Glycosylation of a C-2-O-acetyl mannosyl iodide donor in the presence of silver triflate at -40 degrees C initially gave a mixture of the desired alpha-linked mannoside and an orthoacetate resulting from attack at the C-2 acetate. However, upon warming to room temperature the orthoacetate quantitatively rearranged to the desired oligosaccharide. Employing a 3,6-dihydroxy acceptor and subjecting it to double glycosidation quickly afforded high mannose sugars in nearly quantitative yields. Glycosyl iodide donors offer advantages over previously reported chloride donors as the reactions are faster, proceed in higher yields, and are not diminished in higher order constructs. These studies continue to dispel the notion that glycosyl iodides are too reactive to be of synthetic utility.
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Affiliation(s)
| | - Jacquelyn Gervay-Hague
- University of California, Davis, Department of Chemistry, One Shields Ave., Davis, CA 95616
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27
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Viard M, Parolini I, Rawat SS, Fecchi K, Sargiacomo M, Puri A, Blumenthal R. The role of glycosphingolipids in HIV signaling, entry and pathogenesis. Glycoconj J 2005; 20:213-22. [PMID: 15090735 DOI: 10.1023/b:glyc.0000024253.48791.d9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Although HIV uses CD4 and coreceptors (CCR5 and CXCR4) for productive infection of T cells, glycosphingolipids (GSL) may play ancillary roles in lymphoid and non-lymphoid cells. Interactions of the HIV Envelope Glycoprotein (Env) with GSL may help HIV in various steps of its pathogenesis. Physical-chemical aspects of the interactions between HIV Env and GSL leading to CD4-dependent entry into lymphocytes, the role of GSL in HIV transcytosis, and CD4-independent entry into non-lymphoid cells are reviewed. An overview of signaling properties of HIV receptors is provided with some speculation on how GSL may play a role in these events by virtue of being in membrane rafts. Finally, we summarize how interactions between HIV and coreceptors leading to signaling and/or fusion can be analyzed by the use of various tyrosine kinase and cytoskeletal inhibitors.
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Affiliation(s)
- Mathias Viard
- Laboratory of Experimental and Computational Biology, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, MD, USA
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28
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Augustin LA, Fantini J, Mootoo DR. C-Glycoside analogues of beta-galactosylceramide with a simple ceramide substitute: synthesis and binding to HIV-1 gp120. Bioorg Med Chem 2005; 14:1182-8. [PMID: 16216516 DOI: 10.1016/j.bmc.2005.09.044] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Revised: 09/15/2005] [Accepted: 09/15/2005] [Indexed: 11/28/2022]
Abstract
The synthesis and HIV-1 gp120 binding of C- and aza-C-glycoside analogues of beta-galactosylceramide (GalCer) that contain a simple C-17 hydrocarbon chain as a ceramide substitute are described. Both compounds originate from stearic acid, and a carbohydrate-derived thioacetal-alcohol, and their syntheses are potentially general for beta-C-galactosides and their aza-C-partners. They showed potent and specific affinity for gp120 in an assay based on the change of surface pressure when the glycolipid monolayers were exposed to solutions of gp120. Interestingly, the aza-C-glycoside exhibited a significantly higher affinity than GalCer, whereas the C-glycoside was as active as GalCer.
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Affiliation(s)
- Line A Augustin
- Department of Chemistry, Hunter College, New York, NY 10021, USA
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29
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Liu J, Conboy JC. 1,2-diacyl-phosphatidylcholine flip-flop measured directly by sum-frequency vibrational spectroscopy. Biophys J 2005; 89:2522-32. [PMID: 16085770 PMCID: PMC1366751 DOI: 10.1529/biophysj.105.065672] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Accepted: 07/19/2005] [Indexed: 11/18/2022] Open
Abstract
Sum-frequency vibrational spectroscopy (SFVS) is used to measure the intrinsic rate of lipid flip-flop for 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) in planar-supported lipid bilayers (PSs). Asymmetric PSLBs were prepared using the Langmuir-Blodgett/Langmuir-Schaefer method by placing a perdeuterated lipid analog in one leaflet of the PSLB. SFVS was used to directly measure the asymmetric distribution of the native lipid within the membrane by measuring the decay in the CH3 v(s) intensity at 2875 cm(-1) with time and as a function of temperature. An average activation energy of 220 kJ/mol for the translocation of DMPC, DPPC, and DSPC was determined. A decrease in alkyl chain length resulted in a substantial increase in the rate of flip-flop manifested as an increase in the Arrhenius preexponential factor. The effect of lipid labeling was investigated by measuring the exchange of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-n,n-Dimethyl-n-(2',2',6',6'-tetramethyl-4'-piperidyl) (TEMPO-DPPC). The rate of TEMPO-DPPC flip-flop was an order-of-magnitude slower compared to DPPC. An activation energy of 79 kJ/mol was measured which is comparable to that previously measured by electron spin resonance. The results of this study illustrate how SFVS can be used to directly measure lipid flip-flop without the need for a fluorescent or spin-labeled lipid probe, which can significantly alter the rate of lipid translocation.
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Affiliation(s)
- Jin Liu
- Department of Chemistry, University of Utah, Salt Lake City, UT, USA
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30
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Liu J, Conboy JC. Structure of a gel phase lipid bilayer prepared by the Langmuir-Blodgett/Langmuir-Schaefer method characterized by sum-frequency vibrational spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:9091-7. [PMID: 16171337 DOI: 10.1021/la051500e] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The structure of a planar supported lipid bilayer (PSLB) prepared by the Langmuir-Blodgett (LB)/Langmuir-Schaefer (LS) method was investigated by sum-frequency vibrational spectroscopy (SFVS). By using asymmetric lipid bilayers composed of selectively deuterated 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) lipids, the orientation of the fatty acid chains and phosphocholine headgroups has been determined independently for both leaflets of the bilayer. The alkyl chains of the lipids were found to be orientated approximately 13 degrees +/- 4 degrees from the surface normal for both leaflets. The lipid chains in both leaflets also contain some gauche content, which is consistent with previous NMR and FTIR studies of similar lipid systems. More importantly, the relative number of gauche defects does not seem to be influenced by the deposition method, LB versus LS. The headgroup orientation for the lipid film in contact with the silica support was determined to be 69 degrees +/- 3 degrees , whereas that in contact with the aqueous phase was 66 degrees +/- 4 degrees from the surface normal. The SFVS results indicate that the structure of the DSPC lipid film in contact with the solid support and the film adjacent to the aqueous phase are nearly identical in structure. These results suggesting the LB/LS deposition method do indeed produce symmetric lipid bilayers. These studies further add to the growing information on the efficacy of PSLBs as suitable models for biological membrane studies.
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Affiliation(s)
- Jin Liu
- Department of Chemistry, University of Utah, 315 S. 1400 E. RM 2020, Salt Lake City, UT 84112, USA
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31
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Brake JM, Daschner MK, Abbott NL. Formation and characterization of phospholipid monolayers spontaneously assembled at interfaces between aqueous phases and thermotropic liquid crystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:2218-2228. [PMID: 15752009 DOI: 10.1021/la0482397] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper reports an experimental investigation of the self-assembly of phospholipids (l-alpha-phosphatidylcholine-beta-oleoyl-gamma-palmitoyl (l-POPC), dipalmitoyl phosphatidylcholine (DPPC), and l-alpha-dilauroyl phosphatidylcholine (l-DLPC)) at interfaces between aqueous phases and the nematic liquid crystal (LC) 4'-pentyl-4-cyanobiphenyl. Stable planar interfaces between the aqueous phases and LCs were created by hosting the LCs within gold grids (square pores with widths of 283 microm and depths of 20 microm). At these interfaces, the presence and lateral organization of the phospholipids leads to interface-driven orientational transitions within the LC. By doping the phospholipids with a fluorescently labeled lipid (Texas Red-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (TR-DPPE)), quantitative epifluorescence microscopy revealed the saturation coverage of phospholipid at the interface to be that of a monolayer with an areal density of approximately 49 +/- 8% relative to hydrated lipid bilayers. By adsorbing phospholipids to the aqueous-LC interface from either vesicles or mixed micelles of dodecyltrimethylammonium and phospholipid, control of the areal density of phospholipid from 42 +/- 10 to 102 +/-18% of saturation monolayer coverage was demonstrated. Fluorescence recovery after photobleaching (FRAP) experiments performed by using laser scanning confocal microscopy (LSCM) revealed the lateral mobility of fluorescently labeled DPPE in l-DLPC assembled at the interface with the liquid crystal to be (6 +/- 1) x 10(-12) m(2)/s for densely packed monolayers. Variation of the surface coverage and composition of phospholipid led to changes in lateral diffusivity between (0.2 +/- 0.1) x 10(-12) and (15 +/- 2) x 10(-12) m(2)/s. We also observed the phospholipid-laden interface to be compartmentalized by the gold grid, thus allowing for the creation of patterned arrays of phospholipids at the LC-aqueous interface.
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Affiliation(s)
- Jeffrey M Brake
- Department of Chemical Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706, USA
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32
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Daoudi JM, Greiner J, Aubertin AM, Vierling P. New bicyclam-GalCer analogue conjugates: synthesis and in vitro anti-HIV activity. Bioorg Med Chem Lett 2004; 14:495-8. [PMID: 14698189 DOI: 10.1016/j.bmcl.2003.10.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The synthesis of bipharmacophore anti-HIV compounds which, in a single molecule, combine two ligands, that is, the bicyclam AMD3100 and a GalCer analogue, that might inhibit several steps of the complex virus/cell cascade interactions has been performed. The 'double-drug' Gal-AMD3100 conjugates elicited inhibitory effects on T (or X4)-tropic HIV-1 replication in all CXCR4 expressing cell lines with EC(50) values ranging from 0.25 to 6.0 microM which were however approximately 40- to 125-fold lower than that of AMD3100. Concerning the mechanism of inhibition of the Gal-AMD3100 conjugates, experiments performed with X4 or R5HIV-1 strains and GHOST cells genetically modified to express CD4 and CXCR4 or CCR5 indicated clearly that the conjugates interact with CXCR4 and not with CCR5.
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Affiliation(s)
- Jean-Michel Daoudi
- Laboratoire de Chimie Bioorganique UMR-CNRS 6001, Université de Nice-Sophia Antipolis, Parc Valrose, 06108 Cédex 2, Nice, France
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33
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Kensinger RD, Yowler BC, Benesi AJ, Schengrund CL. Synthesis of Novel, Multivalent Glycodendrimers as Ligands for HIV-1 gp120. Bioconjug Chem 2004; 15:349-58. [PMID: 15025531 DOI: 10.1021/bc034156a] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Multivalent neoglycoconjugates are valuable tools for studying carbohydrate-protein interactions. To study the interaction of HIV-1 gp120 with its reported alternate glycolipid receptors, galactosyl ceramide (GalCer) and sulfatide, galactose- and sulfated galactose-derivatized dendrimers were synthesized, analyzed as ligands for rgp120 by surface plasmon resonance, and tested for their ability to inhibit HIV-1 infection of CXCR4- and CCR5-expressing indicator cells. Four different series of glycodendrimers were made by amine coupling spacer-arm derivatized galactose residues, either sulfated or nonsulfated, to poly(propylenimine) dendrimers, generations 1-5. One series of glycodendrimers was prepared from the ceramide saccharide derivative of purified natural GalCer, and another was from chemically synthesized 3-(beta-D-galactopyranosylthio)propionic acid. Synthesis of 3-sulfogalactopyranosyl-derivatized dendrimers was accomplished using the novel compound, 3-(beta-D-3-sulfogalactopyranosylthio)propionic acid. The fourth series was made by random sulfation of the 3-(beta-D-galactopyranosylthio)propionic acid functionalized dendrimers. Structures of the carbohydrate moieties were confirmed by NMR, and the average molecular weights and polydispersities of the different glycodendrimers were determined using MALDI-TOF MS. Surface plasmon resonance studies found that rgp120 IIIB bound to the derivatized dendrimers tested with nanomolar affinity, and to dextran sulfate with picomolar affinity. In vitro studies of the effectiveness of these compounds at inhibiting infection of U373-MAGI-CCR5 cells by HIV-1 Ba-L indicated that the sulfated glycodendrimers were better inhibitors than the nonsulfated glycodendrimers, but not as effective as dextran sulfate.
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Affiliation(s)
- Richard D Kensinger
- Department of Biochemistry and Molecular Biology H171, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, Pennsylvania 17033, USA
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34
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Conboy JC, Liu S, O'Brien DF, Saavedra SS. Planar supported bilayer polymers formed from bis-diene lipids by Langmuir-Blodgett deposition and UV irradiation. Biomacromolecules 2003; 4:841-9. [PMID: 12741807 DOI: 10.1021/bm0256193] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Substrate-supported lipid bilayers have been prepared from bis-diene functionalized phosphorylcholine (PC) lipids and polymerized by UV irradiation. The overall bilayer structure is largely preserved upon removal from water, although significant loss of material occurs from the upper leaflet of the bilayer, likely due to desorption at the air/water interface. The morphology and surface structure of the bilayer, as observed by AFM, indicate a substantially different arrangement of the lipids in the hydrated and dehydrated states, presumably due to the loss of water from the near surface region. These changes have been correlated with infrared spectral shifts sensitive to the conformation of the hydrocarbon chains. Protein adsorption studies show that rehydrated, polymerized bilayers retain a degree of resistance to BSA adsorption intermediate between model hydrophobic and fluid PC lipid bilayer surfaces. The degree of protein adsorption is correlated with desorption of material from the upper leaflet of the bilayer upon drying, which produces voids at which hydrophobically driven protein adsorption occurs.
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Affiliation(s)
- John C Conboy
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA
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35
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Azefu Y, Tamiaki H, Sato R, Toma K. Facile synthesis of stable lipid analogues possessing a range of alkyl groups: application to artificial glycolipids. Bioorg Med Chem 2002; 10:4013-22. [PMID: 12413853 DOI: 10.1016/s0968-0896(02)00266-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Efficient preparation of lipid analogues is described in which various long alkoxy chains and 2-hydroxyethyl group were covalently linked with benzoic acid derivatives. An alpha-mannopyranosyl group was stereoselectively introduced by the conventional imidate method into the terminal hydroxy group without any alternation of other moieties in a molecule. The resulting new glycoconjugates acted as models of natural glycolipids for protein-carbohydrate interactions.
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Affiliation(s)
- Yasuo Azefu
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga, Japan
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