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Sample records for aba-type structured lipids

  1. Lipid Structure in Triolein Lipid Droplets

    DEFF Research Database (Denmark)

    Chaban, Vitaly V; Khandelia, Himanshu

    2014-01-01

    Lipid droplets (LDs) are primary repositories of esterified fatty acids and sterols in animal cells. These organelles originate on the lumenal or cytoplasmic side of endoplasmic reticulum (ER) membrane and are released to the cytosol. In contrast to other intracellular organelles, LDs are composed...... of a mass of hydrophobic lipid esters coved by phospholipid monolayer. The small size and unique architecture of LDs makes it complicated to study LD structure by modern experimental methods. We discuss coarse-grained molecular dynamics (MD) simulations of LD formation in systems containing 1-palmitoyl-2...... to coarse-grained simulations, the presence of PE lipids at the interface has a little impact on distribution of components and on the overall LD structure. (4) The thickness of the lipid monolayer at the surface of the droplet is similar to the thickness of one leaflet of a bilayer. Computer simulations...

  2. Phase structure of liposome in lipid mixtures.

    Science.gov (United States)

    Zhang, Tianxi; Li, Yuzhuo; Mueller, Anja

    2011-11-01

    Gas microbubbles present in ultrasound imaging contrast agents are stabilized by lipid aggregates that typically contain a mixture of lipids. In this study, the phase structure of the lipid mixtures that contained two or three lipids was investigated using three different methods: dynamic light scattering, (1)H NMR, and microfluidity measurements with fluorescence probes. Three lipids that are commonly present in imaging agents (DPPC, DPPE-PEG, and DPPA) were used. Two types of systems, two-lipid model systems and simulated imaging systems were investigated. The results show that liposomes were the dominant aggregates in all the samples studied. The polar PEG side chains from the PEGylated lipid lead to the formation of micelles and micellar aggregates in small sizes. In the ternary lipid systems, almost all the lipids were present in bilayers with micelles absent and free lipids at very low concentration. These results suggest that liposomes, not micelles, contribute to the stabilization of microbubbles in an ultrasound imaging contrast agent.

  3. The Structure of Cholesterol in Lipid Rafts

    CERN Document Server

    Toppozini, Laura; Armstrong, Clare L; Yamani, Zahra; Kucerka, Norbert; Schmid, Friederike; Rheinstaedter, Maikel C

    2014-01-01

    Rafts, or functional domains, are transient nano- or mesoscopic structures in the plasma membrane and are thought to be essential for many cellular processes such as signal transduction, adhesion, trafficking and lipid/protein sorting. Observations of these membrane heterogeneities have proven challenging, as they are thought to be both small and short-lived. With a combination of coarse-grained molecular dynamics simulations and neutron diffraction using deuterium labeled cholesterol molecules we observe raft-like structures and determine the ordering of the cholesterol molecules in binary cholesterol-containing lipid membranes. From coarse-grained computer simulations, heterogenous membranes structures were observed and characterized as small, ordered domains. Neutron diffraction was used to study the lateral structure of the cholesterol molecules. We find pairs of strongly bound cholesterol molecules in the liquid-disordered phase, in accordance with the umbrella model. Bragg peaks corresponding to orderin...

  4. 2011 Plant Lipids: Structure, Metabolism, & Function Gordon Research Conference

    Energy Technology Data Exchange (ETDEWEB)

    Christopher Benning

    2011-02-04

    This is the second Gordon Research Conference on 'Plant Lipids: Structure, Metabolism & Function'. It covers current topics in lipid structure, metabolism and function in eukaryotic photosynthetic organisms including seed plants, algae, mosses and ferns. Work in photosynthetic bacteria is considered as well as it serves the understanding of specific aspects of lipid metabolism in plants. Breakthroughs are discussed in research on plant lipids as diverse as glycerolipids, sphingolipids, lipids of the cell surface, isoprenoids, fatty acids and their derivatives. The program covers nine concepts at the forefront of research under which afore mentioned plant lipid classes are discussed. The goal is to integrate areas such as lipid signaling, basic lipid metabolism, membrane function, lipid analysis, and lipid engineering to achieve a high level of stimulating interaction among diverse researchers with interests in plant lipids. One Emphasis is on the dynamics and regulation of lipid metabolism during plant cell development and in response to environmental factors.

  5. Structure of Cholesterol in Lipid Rafts

    Science.gov (United States)

    Toppozini, Laura; Meinhardt, Sebastian; Armstrong, Clare L.; Yamani, Zahra; Kučerka, Norbert; Schmid, Friederike; Rheinstädter, Maikel C.

    2014-11-01

    Rafts, or functional domains, are transient nano-or mesoscopic structures in the plasma membrane and are thought to be essential for many cellular processes such as signal transduction, adhesion, trafficking, and lipid or protein sorting. Observations of these membrane heterogeneities have proven challenging, as they are thought to be both small and short lived. With a combination of coarse-grained molecular dynamics simulations and neutron diffraction using deuterium labeled cholesterol molecules, we observe raftlike structures and determine the ordering of the cholesterol molecules in binary cholesterol-containing lipid membranes. From coarse-grained computer simulations, heterogenous membranes structures were observed and characterized as small, ordered domains. Neutron diffraction was used to study the lateral structure of the cholesterol molecules. We find pairs of strongly bound cholesterol molecules in the liquid-disordered phase, in accordance with the umbrella model. Bragg peaks corresponding to ordering of the cholesterol molecules in the raftlike structures were observed and indexed by two different structures: a monoclinic structure of ordered cholesterol pairs of alternating direction in equilibrium with cholesterol plaques, i.e., triclinic cholesterol bilayers.

  6. Sphingolipid symmetry governs membrane lipid raft structure.

    Science.gov (United States)

    Quinn, Peter J

    2014-07-01

    Lipid domain formation in membranes underlies the concept of rafts but their structure is controversial because the key role of cholesterol has been challenged. The configuration of glycosphingolipid receptors for agonists, bacterial toxins and enveloped viruses in plasma membrane rafts appears to be an important factor governing ligand binding and infectivity but the details are as yet unresolved. I have used X-ray diffraction methods to examine how cholesterol affects the distribution of glycosphingolipid in aqueous dispersions of an equimolar mixture of cholesterol and egg-sphingomyelin containing different proportions of glucosylceramide from human extracts. Three coexisting liquid-ordered bilayer structures are observed at 37°C in mixtures containing up to 20mol% glycosphingolipid. All the cholesterol was sequestered in one bilayer with the minimum amount of sphingomyelin (33mol%) to prevent formation of cholesterol crystals. The other two bilayers consisted of sphingomyelin and glucosylceramide. Asymmetric molecular species of glucosylceramide with N-acyl chains longer than 20 carbons form an equimolar complex with sphingomyelin in which the glycosidic residues are arranged in hexagonal array. Symmetric molecular species mix with sphingomyelin in proportions less than equimolar to form quasicrystalline bilayers. When the glycosphingolipid exceeds equimolar proportions with sphingomyelin cholesterol is incorporated into the structure and formation of a gel phase of glucosylceramide is prevented. The demonstration of particular structural features of ceramide molecular species combined with the diversity of sugar residues of glycosphingolipid classes paves the way for a rational approach to understanding the functional specificity of lipid rafts and how they are coupled across cell membranes.

  7. Specific-structured lipids: nutritional perspectives and production potentials

    DEFF Research Database (Denmark)

    Xu, Xuebing; Høy, Carl-Erik; Balchen, Steen

    1997-01-01

    Structured lipids are referring to any triacylglycerols containing both long chain fatty acids (mostly essential fatty acids) and medium or short chain fatty acids. In case of specific-structured lipids (SSLs), each group of fatty acids locates specifically at sn-2 or -1.3 positions of the glycerol...

  8. Performance of structured lipids incorporating selected phenolic and ascorbic acids.

    Science.gov (United States)

    Gruczynska, Eliza; Przybylski, Roman; Aladedunye, Felix

    2015-04-15

    Conditions applied during frying require antioxidant which is stable at these conditions and provides protection for frying oil and fried food. Novel structured lipids containing nutraceuticals and antioxidants were formed by enzymatic transesterification, exploring canola oil and naturally occurring antioxidants such as ascorbic and selected phenolic acids as substrates. Lipozyme RM IM lipase from Rhizomucor miehei was used as biocatalyst. Frying performance and oxidative stability of the final transesterification products were evaluated. The novel lipids showed significantly improved frying performance compared to canola oil. Oxidative stability assessment of the structured lipids showed significant improvement in resistance to oxidative deterioration compared to original canola oil. Interestingly, the presence of ascorbic acid in an acylglycerol structure protected α-tocopherol against thermal degradation, which was not observed for the phenolic acids. Developed structured lipids containing nutraceuticals and antioxidants may directly affect nutritional properties of lipids also offering nutraceutical ingredients for food formulation.

  9. Multiscale structures of lipids in foods as parameters affecting fatty acid bioavailability and lipid metabolism.

    Science.gov (United States)

    Michalski, M C; Genot, C; Gayet, C; Lopez, C; Fine, F; Joffre, F; Vendeuvre, J L; Bouvier, J; Chardigny, J M; Raynal-Ljutovac, K

    2013-10-01

    On a nutritional standpoint, lipids are now being studied beyond their energy content and fatty acid (FA) profiles. Dietary FA are building blocks of a huge diversity of more complex molecules such as triacylglycerols (TAG) and phospholipids (PL), themselves organised in supramolecular structures presenting different thermal behaviours. They are generally embedded in complex food matrixes. Recent reports have revealed that molecular and supramolecular structures of lipids and their liquid or solid state at the body temperature influence both the digestibility and metabolism of dietary FA. The aim of the present review is to highlight recent knowledge on the impact on FA digestion, absorption and metabolism of: (i) the intramolecular structure of TAG; (ii) the nature of the lipid molecules carrying FA; (iii) the supramolecular organization and physical state of lipids in native and formulated food products and (iv) the food matrix. Further work should be accomplished now to obtain a more reliable body of evidence and integrate these data in future dietary recommendations. Additionally, innovative lipid formulations in which the health beneficial effects of either native or recomposed structures of lipids will be taken into account can be foreseen.

  10. Structural characterization and lipid composition of acquired cholesteatoma

    DEFF Research Database (Denmark)

    Bloksgaard, Maria; Svane-Knudsen, Viggo; Sørensen, Jens A

    2012-01-01

    along a depth of more than 200 μm and resembles the stratum corneum of hyperorthokeratotic skin. Lipid compositional analyses of the cholesteatoma show the presence of all major lipid classes found in normal skin stratum corneum (ceramides, long chain fatty acids, and cholesterol). Consistent with this......HYPOTHESIS: The goal of this work is to characterize the morphology and lipid composition of acquired cholesteatoma. We hypothesize that constitutive lipid membranes are present in the cholesteatoma and resemble those found in human skin stratum corneum. METHODS: We performed a comparative...... noninvasive structural and lipid compositional study of acquired cholesteatoma and control human skin using multiphoton excitation fluorescence microscopy-related techniques and high-performance thin-layer chromatography. RESULTS: The structural arrangement of the cholesteatoma is morphologically invariant...

  11. Lipids: From Chemical Structures, Biosynthesis, and Analyses to Industrial Applications.

    Science.gov (United States)

    Li-Beisson, Yonghua; Nakamura, Yuki; Harwood, John

    2016-01-01

    Lipids are one of the major subcellular components, and play numerous essential functions. As well as their physiological roles, oils stored in biomass are useful commodities for a variety of biotechnological applications including food, chemical feedstocks, and fuel. Due to their agronomic as well as economic and societal importance, lipids have historically been subjected to intensive studies. Major current efforts are to increase the energy density of cell biomass, and/or create designer oils suitable for specific applications. This chapter covers some basic aspects of what one needs to know about lipids: definition, structure, function, metabolism and focus is also given on the development of modern lipid analytical tools and major current engineering approaches for biotechnological applications. This introductory chapter is intended to serve as a primer for all subsequent chapters in this book outlining current development in specific areas of lipids and their metabolism.

  12. Effect of training on muscle triacylglycerol and structural lipids

    DEFF Research Database (Denmark)

    Helge, Jørn W; Dela, Flemming

    2003-01-01

    We studied whether endurance training impacts insulin sensitivity by affecting the structural and storage lipids in humans. Eight male subjects participated (age 25 +/- 1 years, height 178 +/- 3 cm, weight 76 +/- 4 kg [mean +/- SE]). Single-leg training was performed for 30 min/day for 4 weeks...... polyunsaturates, which may indicate that membrane lipids may have a role in the training-induced increase in insulin sensitivity....

  13. Lipid nanotechnologies for structural studies of membrane-associated proteins.

    Science.gov (United States)

    Stoilova-McPhie, Svetla; Grushin, Kirill; Dalm, Daniela; Miller, Jaimy

    2014-11-01

    We present a methodology of lipid nanotubes (LNT) and nanodisks technologies optimized in our laboratory for structural studies of membrane-associated proteins at close to physiological conditions. The application of these lipid nanotechnologies for structure determination by cryo-electron microscopy (cryo-EM) is fundamental for understanding and modulating their function. The LNTs in our studies are single bilayer galactosylceramide based nanotubes of ∼20 nm inner diameter and a few microns in length, that self-assemble in aqueous solutions. The lipid nanodisks (NDs) are self-assembled discoid lipid bilayers of ∼10 nm diameter, which are stabilized in aqueous solutions by a belt of amphipathic helical scaffold proteins. By combining LNT and ND technologies, we can examine structurally how the membrane curvature and lipid composition modulates the function of the membrane-associated proteins. As proof of principle, we have engineered these lipid nanotechnologies to mimic the activated platelet's phosphtaidylserine rich membrane and have successfully assembled functional membrane-bound coagulation factor VIII in vitro for structure determination by cryo-EM. The macromolecular organization of the proteins bound to ND and LNT are further defined by fitting the known atomic structures within the calculated three-dimensional maps. The combination of LNT and ND technologies offers a means to control the design and assembly of a wide range of functional membrane-associated proteins and complexes for structural studies by cryo-EM. The presented results confirm the suitability of the developed methodology for studying the functional structure of membrane-associated proteins, such as the coagulation factors, at a close to physiological environment. © 2014 Wiley Periodicals, Inc.

  14. Skin lipid structure controls water permeability in snake molts.

    Science.gov (United States)

    Torri, Cristian; Mangoni, Alfonso; Teta, Roberta; Fattorusso, Ernesto; Alibardi, Lorenzo; Fermani, Simona; Bonacini, Irene; Gazzano, Massimo; Burghammer, Manfred; Fabbri, Daniele; Falini, Giuseppe

    2014-01-01

    The role of lipids in controlling water exchange is fundamentally a matter of molecular organization. In the present study we have observed that in snake molt the water permeability drastically varies among species living in different climates and habitats. The analysis of molts from four snake species: tiger snake, Notechis scutatus, gabon viper, Bitis gabonica, rattle snake, Crotalus atrox, and grass snake, Natrix natrix, revealed correlations between the molecular composition and the structural organization of the lipid-rich mesos layer with control in water exchange as a function of temperature. It was discovered, merging data from micro-diffraction and micro-spectroscopy with those from thermal, NMR and chromatographic analyses, that this control is generated from a sophisticated structural organization that changes size and phase distribution of crystalline domains of specific lipid molecules as a function of temperature. Thus, the results of this research on four snake species suggest that in snake skins different structured lipid layers have evolved and adapted to different climates. Moreover, these lipid structures can protect, "safety", the snakes from water lost even at temperatures higher than those of their usual habitat.

  15. Comparative structural analysis of lipid binding START domains.

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    Ann-Gerd Thorsell

    Full Text Available BACKGROUND: Steroidogenic acute regulatory (StAR protein related lipid transfer (START domains are small globular modules that form a cavity where lipids and lipid hormones bind. These domains can transport ligands to facilitate lipid exchange between biological membranes, and they have been postulated to modulate the activity of other domains of the protein in response to ligand binding. More than a dozen human genes encode START domains, and several of them are implicated in a disease. PRINCIPAL FINDINGS: We report crystal structures of the human STARD1, STARD5, STARD13 and STARD14 lipid transfer domains. These represent four of the six functional classes of START domains. SIGNIFICANCE: Sequence alignments based on these and previously reported crystal structures define the structural determinants of human START domains, both those related to structural framework and those involved in ligand specificity. ENHANCED VERSION: This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available in Text S1.

  16. Non-lamellar lipid liquid crystalline structures at interfaces.

    Science.gov (United States)

    Chang, Debby P; Barauskas, Justas; Dabkowska, Aleksandra P; Wadsäter, Maria; Tiberg, Fredrik; Nylander, Tommy

    2015-08-01

    The self-assembly of lipids leads to the formation of a rich variety of nano-structures, not only restricted to lipid bilayers, but also encompassing non-lamellar liquid crystalline structures, such as cubic, hexagonal, and sponge phases. These non-lamellar phases have been increasingly recognized as important for living systems, both in terms of providing compartmentalization and as regulators of biological activity. Consequently, they are of great interest for their potential as delivery systems in pharmaceutical, food and cosmetic applications. The compartmentalizing nature of these phases features mono- or bicontinuous networks of both hydrophilic and hydrophobic domains. To utilize these non-lamellar liquid crystalline structures in biomedical devices for analyses and drug delivery, it is crucial to understand how they interact with and respond to different types of interfaces. Such non-lamellar interfacial layers can be used to entrap functional biomolecules that respond to lipid curvature as well as the confinement. It is also important to understand the structural changes of deposited lipid in relation to the corresponding bulk dispersions. They can be controlled by changing the lipid composition or by introducing components that can alter the curvature or by deposition on nano-structured surface, e.g. vertical nano-wire arrays. Progress in the area of liquid crystalline lipid based nanoparticles opens up new possibilities for the preparation of well-defined surface films with well-defined nano-structures. This review will focus on recent progress in the formation of non-lamellar dispersions and their interfacial properties at the solid/liquid and biologically relevant interfaces.

  17. Purification and deodorization of structured lipids by short path distillation

    DEFF Research Database (Denmark)

    Xu, Xuebing; Jacobsen, Charlotte; Nielsen, Nina Skall;

    2002-01-01

    Purification of structured lipids (SL), produced from lipase- catalyzed acidolysis of rapeseed oil and capric acid, and deodorization of randomized SL, produced from chemical randomization of fish oil and tricaprin, were studied in a bench-scale short path distillation (SPD). SL obtained from...

  18. Purification and deodorization of structured lipids by short path distillation

    DEFF Research Database (Denmark)

    Xu, Xuebing; Jacobsen, Charlotte; Nielsen, Nina Skall

    2002-01-01

    Purification of structured lipids (SL), produced from lipase- catalyzed acidolysis of rapeseed oil and capric acid, and deodorization of randomized SL, produced from chemical randomization of fish oil and tricaprin, were studied in a bench-scale short path distillation (SPD). SL obtained from...

  19. Oxidative stability during storage of structured lipids produced from fish oil and caprylic acid

    DEFF Research Database (Denmark)

    Nielsen, Nina Skall; Xu, Xuebing; Timm Heinrich, Maike;

    2004-01-01

    Structured lipids produced by enzymatic or chemical methods for different applications have been receiving considerable attention. The oxidative stability of a randomized structured lipid (RFO), produced by chemical interesterification from fish oil (FO) and tricaprylin, and a specific structured...

  20. Data supporting beta-amyloid dimer structural transitions and protein–lipid interactions on asymmetric lipid bilayer surfaces using MD simulations on experimentally derived NMR protein structures

    Directory of Open Access Journals (Sweden)

    Sara Y. Cheng

    2016-06-01

    Full Text Available This data article supports the research article entitled “Maximally Asymmetric Transbilayer Distribution of Anionic Lipids Alters the Structure and interaction with Lipids of an Amyloidogenic Protein Dimer Bound to the Membrane Surface” [1]. We describe supporting data on the binding kinetics, time evolution of secondary structure, and residue-contact maps of a surface-absorbed beta-amyloid dimer protein on different membrane surfaces. We further demonstrate the sorting of annular and non-annular regions of the protein/lipid bilayer simulation systems, and the correlation of lipid-number mismatch and surface area per lipid mismatch of asymmetric lipid membranes.

  1. Tethered and Polymer Supported Bilayer Lipid Membranes: Structure and Function

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    Jakob Andersson

    2016-05-01

    Full Text Available Solid supported bilayer lipid membranes are model systems to mimic natural cell membranes in order to understand structural and functional properties of such systems. The use of a model system allows for the use of a wide variety of analytical tools including atomic force microscopy, impedance spectroscopy, neutron reflectometry, and surface plasmon resonance spectroscopy. Among the large number of different types of model membranes polymer-supported and tethered lipid bilayers have been shown to be versatile and useful systems. Both systems consist of a lipid bilayer, which is de-coupled from an underlying support by a spacer cushion. Both systems will be reviewed, with an emphasis on the effect that the spacer moiety has on the bilayer properties.

  2. DNA-Tile Structures Induce Ionic Currents through Lipid Membranes.

    Science.gov (United States)

    Göpfrich, Kerstin; Zettl, Thomas; Meijering, Anna E C; Hernández-Ainsa, Silvia; Kocabey, Samet; Liedl, Tim; Keyser, Ulrich F

    2015-05-13

    Self-assembled DNA nanostructures have been used to create man-made transmembrane channels in lipid bilayers. Here, we present a DNA-tile structure with a nominal subnanometer channel and cholesterol-tags for membrane anchoring. With an outer diameter of 5 nm and a molecular weight of 45 kDa, the dimensions of our synthetic nanostructure are comparable to biological ion channels. Because of its simple design, the structure self-assembles within a minute, making its creation scalable for applications in biology. Ionic current recordings demonstrate that the tile structures enable ion conduction through lipid bilayers and show gating and voltage-switching behavior. By demonstrating the design of DNA-based membrane channels with openings much smaller than that of the archetypical six-helix bundle, our work showcases their versatility inspired by the rich diversity of natural membrane components.

  3. Structural investigations on lipid nanoparticles containing high amounts of lecithin.

    Science.gov (United States)

    Schubert, Martin Alexander; Harms, Meike; Müller-Goymann, Christel Charlotte

    2006-02-01

    Solid lipid nanoparticles (SLN), an alternative colloidal drug delivery system to polymer nanoparticles, emulsions and liposomes, possess inherent low incorporation rates resulting from the crystalline structure of the solid lipid. To increase the drug loading capacity of SLN, matrix modification by incorporation of the amphiphilic lipid lecithin within the lipid matrices has been proposed as a promising alternative. The objective of this work is to investigate the effects of the lecithin on the microstructure of matrix modified SLN. In addition, these systems were checked for the existence of aggregates like mixed micelles, liposomes, etc., which could possibly be formed by lecithin leakage into the aqueous phase during the preparation process. For this purpose, laser diffraction, photon correlation spectroscopy (PCS), small angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM) were performed to investigate the structure, mobility, and molecular environment of the compounds. Lecithin incorporation within the lipid matrices resulted in a concentration dependent decrease in particle size up to a critical concentration of 30%. Lecithin incorporation up to 50% was investigated but caused no further particle size decrease. TEM revealed anisometrical and crystalline platelets of ellipsoidal to disc-like shape. Furthermore, SAXS and TEM showed no signs of lecithin and nonionic emulsifier derived aggregates in the aqueous phase. This points in agreement with NMR measurements to a strong attachment of both substances to the SLN surfaces. The proposed structure of the particles after melt emulsification consists of two different layers: a crystalline triglyceride-rich core is covered in dependence of the lecithin content either by a monomolecular or multimolecular lecithin/Solutol HS15 (SOL) layer.

  4. Structure and Biosynthesis of Cuticular Lipids

    Science.gov (United States)

    Kolattukudy, P. E.; Croteau, Rodney; Brown, Linda

    1974-01-01

    The structure and composition of the cutin monomers from the flower petals of Vicia faba were determined by hydrogenolysis (LiAlH4) or deuterolysis (LiAlD4) followed by thin layer chromatography and combined gas-liquid chromatography and mass spectrometry. The major components were 10, 16-dihydroxyhexadecanoic acid (79.8%), 9, 16-dihydroxyhexadecanoic acid (4.2%), 16-hydroxyhexadecanoic acid (4.2%), 18-hydroxyoctadecanoic acid (1.6%), and hexadecanoic acid (2.4%). These results show that flower petal cutin is very similar to leaf cutin of V. faba. Developing petals readily incorporated exogenous [1-14C]palmitic acid into cutin. Direct conversion of the exogeneous acid into 16-hydroxyhexadecanoic acid, 10, 16-dihydroxy-, and 9, 16-dihydroxyhexadecanoic acid was demonstrated by radio gas-liquid chromatography of their chemical degradation products. About 1% of the exogenous [1-14C]palmitic acid was incorporated into C27, C29, and C31n-alkanes, which were identified by combined gas-liquid chromatography and mass spectrometry as the major components of the hydrocarbons of V. faba flowers. The radioactivity distribution among these three alkanes (C27, 15%; C29, 48%; C31, 38%) was similar to the per cent composition of the alkanes (C27, 12%; C29, 43%; C31, 44%). [1-14C]Stearic acid was also incorporated into C27, C29, and C31n-alkanes in good yield (3%). Trichloroacetate, which has been postulated to be an inhibitor of fatty acid elongation, inhibited the conversion of [1-14C]stearic acid to alkanes, and the inhibition was greatest for the longer alkanes. Developing flower petals also incorporated exogenous C28, C30, and C32 acids into alkanes in 0.5% to 5% yields. [G-3H]n-octacosanoic acid (C28) was incorporated into C27, C29, and C31n-alkanes. [G-3H]n-triacontanoic acid (C30) was incorporated mainly into C29 and C31 alkanes, whereas [9, 10, 11-3H]n-dotriacontanoic acid (C32) was converted mainly to C31 alkane. Trichloroacetate inhibited the conversion of the exogenous

  5. Production of specific-structured lipids by enzymatic interesterification in a pilot continuous enzyme bed reactor

    DEFF Research Database (Denmark)

    Xu, Xuebing; Balchen, Steen; Høy, Carl-Erik;

    1998-01-01

    Production of specific-structured lipids (interesterified lipids with a specific structure) by enzymatic interesterification was carried out in a continuous enzyme bed pilot scale reactor. Commercial immobilized lipase (Lipozyme IM) was used and investigations of acyl migration, pressure drop...

  6. A Molecular Dynamics Study of the Structural and Dynamical Properties of Putative Arsenic Substituted Lipid Bilayers

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    Ratna Juwita

    2013-04-01

    Full Text Available Cell membranes are composed mainly of phospholipids which are in turn, composed of five major chemical elements: carbon, hydrogen, nitrogen, oxygen, and phosphorus. Recent studies have suggested the possibility of sustaining life if the phosphorus is substituted by arsenic. Although this issue is still controversial, it is of interest to investigate the properties of arsenated-lipid bilayers to evaluate this possibility. In this study, we simulated arsenated-lipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-arsenocholine (POAC, lipid bilayers using all-atom molecular dynamics to understand basic structural and dynamical properties, in particular, the differences from analogous 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, (POPC lipid bilayers. Our simulations showed that POAC lipid bilayers have distinct structural and dynamical properties from those of native POPC lipid bilayers. Relative to POPC lipid bilayers, POAC lipid bilayers have a more compact structure with smaller lateral areas and greater order. The compact structure of POAC lipid bilayers is due to the fact that more inter-lipid salt bridges are formed with arsenate-choline compared to the phosphate-choline of POPC lipid bilayers. These inter-lipid salt bridges bind POAC lipids together and also slow down the head group rotation and lateral diffusion of POAC lipids. Thus, it would be anticipated that POAC and POPC lipid bilayers would have different biological implications.

  7. Synthesis of resorcinolic lipids bearing structural similarities to cytosporone A

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    Edson dos Anjos dos Santos

    2009-01-01

    Full Text Available Inspired by the structure and biological activities of resorcinolic lipids and, particularly cytosporone A- a potent inhibitor of plantule germination and growth, we have performed the synthesis of the analogs 3-heptyl-3-hydroxy-5,7-dimethoxy-2-benzofuran-1(3H-one (1 and 3-heptyl-3-hydroxy-4,6-dimethoxy-2-benzofuran-1(3H-one (2. The intermediates and products were submitted to allelopathic test using Lactuca sativa L. seeds. Target compound 1 showed an inhibitory effect on germination and growth of hypocotyl and radicle in milimolar range.

  8. Synthesis of resorcinolic lipids bearing structural similarities to cytosporone A

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Edson dos Anjos dos; Beatriz, Adilson; Lima, Denis Pires de [Universidade Federal Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil). Centro de Ciencias Exatas e Tecnologia. Dept. de Quimica], e-mail: dlima@nin.ufms.br; Marques, Maria Rita; Leite, Carla Braga [Universidade Federal Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil). Centro de Ciencias Biologicas. Dept. de Morfofisiologia

    2009-07-01

    Inspired by the structure and biological activities of resorcinolic lipids and, particularly cytosporone A- a potent inhibitor of plantule germination and growth, we have performed the synthesis of the analogs 3-heptyl-3-hydroxy-5,7-dimethoxy-2-benzofuran-1(3H)-one (1) and 3-heptyl-3-hydroxy-4,6-dimethoxy-2-benzofuran-1(3H)-one (2). The intermediates and products were submitted to allelopathic test using Lactuca sativa L. seeds. Target compound 1 showed an inhibitory effect on germination and growth of hypocotyl and radicle in millimolar range. (author)

  9. Protein-lipid interactions: correlation of a predictive algorithm for lipid-binding sites with three-dimensional structural data

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    Goldmann Wolfgang H

    2006-03-01

    Full Text Available Abstract Background Over the past decade our laboratory has focused on understanding how soluble cytoskeleton-associated proteins interact with membranes and other lipid aggregates. Many protein domains mediating specific cell membrane interactions appear by fluorescence microscopy and other precision techniques to be partially inserted into the lipid bilayer. It is unclear whether these protein-lipid-interactions are dependent on shared protein motifs or unique regional physiochemistry, or are due to more global characteristics of the protein. Results We have developed a novel computational program that predicts a protein's lipid-binding site(s from primary sequence data. Hydrophobic labeling, Fourier transform infrared spectroscopy (FTIR, film balance, T-jump, CD spectroscopy and calorimetry experiments confirm that the interfaces predicted for several key cytoskeletal proteins (alpha-actinin, Arp2, CapZ, talin and vinculin partially insert into lipid aggregates. The validity of these predictions is supported by an analysis of the available three-dimensional structural data. The lipid interfaces predicted by our algorithm generally contain energetically favorable secondary structures (e.g., an amphipathic alpha-helix flanked by a flexible hinge or loop region, are solvent-exposed in the intact protein, and possess favorable local or global electrostatic properties. Conclusion At present, there are few reliable methods to determine the region of a protein that mediates biologically important interactions with lipids or lipid aggregates. Our matrix-based algorithm predicts lipid interaction sites that are consistent with the available biochemical and structural data. To determine whether these sites are indeed correctly identified, and whether use of the algorithm can be safely extended to other classes of proteins, will require further mapping of these sites, including genetic manipulation and/or targeted crystallography.

  10. Dynamical and structural properties of lipid membranes in relation to liposomal drug delivery systems

    DEFF Research Database (Denmark)

    Jørgensen, Kent; Høyrup, Lise Pernille Kristine; Pedersen, Tina B.

    2001-01-01

    The structural and dynamical properties of DPPC liposomes containing lipopolymers (PEG-lipids) and charged DPPS lipids have been,studied in relation to the lipid membrane interaction of enzymes and peptides. The results suggest that both the lipid membrane structure and dynamics and in particular...... the appearance of small-scale lipid structures might be of importance for the activity of membrane associated and liposome degrading enzymes as well as for the membrane interaction of acylated peptides. The combined experimental and simulation results are of relevance for a rational development of peptide loaded...

  11. Influence of encapsulated functional lipids on crystal structure and chemical stability in solid lipid nanoparticles: Towards bioactive-based design of delivery systems.

    Science.gov (United States)

    Salminen, Hanna; Gömmel, Christina; Leuenberger, Bruno H; Weiss, Jochen

    2016-01-01

    We investigated the influence of physicochemical properties of encapsulated functional lipids--vitamin A, β-carotene and ω-3 fish oil--on the structural arrangement of solid lipid nanoparticles (SLN). The relationship between the crystal structure and chemical stability of the incorporated bioactive lipids was evaluated with different emulsifier compositions of a saponin-rich, food-grade Quillaja extract alone or combined with high-melting or low-melting lecithins. The major factors influencing the structural arrangement and chemical stability of functional lipids in solid lipid dispersions were their solubility in the aqueous phase and their crystallization temperature in relation to that of the carrier lipid. The results showed that the stabilization of the α-subcell crystals in the lattice of the carrier lipid is a key parameter for forming stable solid lipid dispersions. This study contributes to a better understanding of SLN as a function of the bioactive lipid. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Non-lamellar lipid assembly at interfaces: controlling layer structure by responsive nanogel particles.

    Science.gov (United States)

    Dabkowska, Aleksandra P; Valldeperas, Maria; Hirst, Christopher; Montis, Costanza; Pálsson, Gunnar K; Wang, Meina; Nöjd, Sofi; Gentile, Luigi; Barauskas, Justas; Steinke, Nina-Juliane; Schroeder-Turk, Gerd E; George, Sebastian; Skoda, Maximilian W A; Nylander, Tommy

    2017-08-06

    Biological membranes do not only occur as planar bilayer structures, but depending on the lipid composition, can also curve into intriguing three-dimensional structures. In order to fully understand the biological implications as well as to reveal the full potential for applications, e.g. for drug delivery and other biomedical devices, of such structures, well-defined model systems are required. Here, we discuss the formation of lipid non-lamellar liquid crystalline (LC) surface layers spin-coated from the constituting lipids followed by hydration of the lipid layer. We demonstrate that hybrid lipid polymer films can be formed with different properties compared with the neat lipid LC layers. The nanostructure and morphologies of the lipid films formed reflect those in the bulk. Most notably, mixed lipid layers, which are composed of glycerol monooleate and diglycerol monooleate with poly(N-isopropylacrylamide) nanogels, can form films of reverse cubic phases that are capable of responding to temperature stimulus. Owing to the presence of the nanogel particles, changing the temperature not only regulates the hydration of the cubic phase lipid films, but also the lateral organization of the lipid domains within the lipid self-assembled film. This opens up the possibility for new nanostructured materials based on lipid-polymer responsive layers.

  13. Structure and fluctuations of a single floating lipid bilayer.

    Science.gov (United States)

    Daillant, J; Bellet-Amalric, E; Braslau, A; Charitat, T; Fragneto, G; Graner, F; Mora, S; Rieutord, F; Stidder, B

    2005-08-16

    A single lipid molecular bilayer of 17 or 18 carbon chain phosphocholines, floating in water near a flat wall, is prepared in the bilayer gel phase and then heated to the fluid phase. Its structure (electron density profile) and height fluctuations are determined by using x-ray reflectivity and non-specular scattering. By fitting the off-specular signal to that calculated for a two-dimensional membrane using a Helfrich Hamiltonian, we determine the three main physical quantities that govern the bilayer height fluctuations: The wall attraction potential is unexpectedly low; the surface tension, roughly independent on chain length and temperature, is moderate (approximately 5 x 10(-4) J.m(-2)) but large enough to dominate the intermediate range of the fluctuation spectrum; and the bending modulus abruptly decreases by an order-of-magnitude from 10(-18) J to 10(-19) J at the bilayer gel-to-fluid transition.

  14. Structural characterization of suppressor lipids by high-resolution mass spectrometry

    DEFF Research Database (Denmark)

    Rovillos, Mary Joy; Pauling, Josch Konstantin; Hannibal-Bach, Hans Kristian

    2016-01-01

    RATIONALE: Suppressor lipids were originally identified in 1993 and reported to encompass six lipid classes that enable Saccharomyces cerevisiae to live without sphingolipids. Structural characterization, using non-mass spectrometric approaches, revealed that these suppressor lipids are very long...... chain fatty acid (VLCFA)-containing glycerophospholipids with polar head groups that are typically incorporated into sphingolipids. Here we report, for the first time, the structural characterization of the yeast suppressor lipids using high-resolution mass spectrometry. METHODS: Suppressor lipids were...... isolated by preparative chromatography and subjected to structural characterization using hybrid quadrupole time-of-flight and ion trap-orbitrap mass spectrometry. RESULTS: Our investigation recapitulates the overall structural features of the suppressor lipids and provides an in-depth characterization...

  15. Structural properties of lipid reconstructs and lipid composition of normotensive and hypertensive rat vascular smooth muscle cell membranes

    Directory of Open Access Journals (Sweden)

    T.R. Oliveira

    2009-09-01

    Full Text Available Multiple cell membrane alterations have been reported to be the cause of various forms of hypertension. The present study focuses on the lipid portion of the membranes, characterizing the microviscosity of membranes reconstituted with lipids extracted from the aorta and mesenteric arteries of spontaneously hypertensive (SHR and normotensive control rat strains (WKY and NWR. Membrane-incorporated phospholipid spin labels were used to monitor the bilayer structure at different depths. The packing of lipids extracted from both aorta and mesenteric arteries of normotensive and hypertensive rats was similar. Lipid extract analysis showed similar phospholipid composition for all membranes. However, cholesterol content was lower in SHR arteries than in normotensive animal arteries. These findings contrast with the fact that the SHR aorta is hyporeactive while the SHR mesenteric artery is hyperreactive to vasopressor agents when compared to the vessels of normotensive animal strains. Hence, factors other than microviscosity of bulk lipids contribute to the vascular smooth muscle reactivity and hypertension of SHR. The excess cholesterol in the arteries of normotensive animal strains apparently is not dissolved in bulk lipids and is not directly related to vascular reactivity since it is present in both the aorta and mesenteric arteries. The lower cholesterol concentrations in SHR arteries may in fact result from metabolic differences due to the hypertensive state or to genes that co-segregate with those that determine hypertension during the process of strain selection.

  16. 2009 Plant Lipids: Structure, Metabolism & Function Gordon Research Conference - February 1- 6 ,2009

    Energy Technology Data Exchange (ETDEWEB)

    Kent D. Chapman

    2009-02-06

    The Gordon Research Conference on 'Plant Lipids: Structure, Metabolism and Function' has been instituted to accelerate research productivity in the field of plant lipids. This conference will facilitate wide dissemination of research breakthroughs, support recruitment of young scientists to the field of plant lipid metabolism and encourage broad participation of the plant lipid community in guiding future directions for research in plant lipids. This conference will build upon the strengths of the successful, previous biannual meetings of the National Plant Lipid Cooperative (www.plantlipids.org) that began in 1993, but will reflect a broader scope of topics to include the biochemistry, cell biology, metabolic regulation, and signaling functions of plant acyl lipids. Most importantly, this conference also will serve as a physical focal point for the interaction of the plant lipid research community. Applications to attend this conference will be open to all researchers interested in plant lipids and will provide a venue for the presentation of the latest research results, networking opportunities for young scientists, and a forum for the development and exchange of useful lipid resources and new ideas. By bringing together senior- and junior-level scientists involved in plant lipid metabolism, a broad range of insights will be shared and the community of plant lipid researchers will function more as a network of vested partners. This is important for the vitality of the research community and for the perceived value that will encourage conference attendance into the future.

  17. Investigation of lipid membrane macro- and micro-structure using calorimetry and computer simulation: structural and functional relationships

    DEFF Research Database (Denmark)

    Jørgensen, Kent; Mouritsen, Ole G.

    1999-01-01

    The lipid bilayer part of biological membranes is a complex lipid mixture displaying cooperative phenomena. By means of differential scanning calorimetry and computer simulation techniques, the equilibrium and non-equilibrium properties of the large assembly of mutually interacting amphiphilic...... lipid molecules constituting the lipid bilayer have been investigated. The cooperative many-particle lipid bilayer behavior is manifested in terms of phase transitions and large-scale macroscopic phase equilibria. On a smaller nanometer length-scale, equilibrium structural and compositional fluctuations...... and proteins. (C) 1999 Published by Elsevier Science B.V. All rights reserved....

  18. Supercritical fluid precipitation of ketoprofen in novel structured lipid carriers for enhanced mucosal delivery--a comparison with solid lipid particles.

    Science.gov (United States)

    Gonçalves, V S S; Matias, A A; Rodríguez-Rojo, S; Nogueira, I D; Duarte, C M M

    2015-11-10

    Structured lipid carriers based on mixture of solid lipids with liquid lipids are the second generation of solid lipid particles, offering the advantage of improved drug loading capacity and higher storage stability. In this study, structured lipid carriers were successfully prepared for the first time by precipitation from gas saturated solutions. Glyceryl monooleate (GMO), a liquid glycerolipid, was selected in this work to be incorporated into three solid glycerolipids with hydrophilic-lipophilic balance (HLB) ranging from 1 to 13, namely Gelucire 43/01™, Geleol™ and Gelucire 50/13™. In general, microparticles with a irregular porous morphology and a wide particle size distribution were obtained. The HLB of the individual glycerolipids might be a relevant parameter to take into account during the processing of solid:liquid lipid blends. As expected, the addition of a liquid lipid into a solid lipid matrix led to increased stability of the lipid carriers, with no significant modifications in their melting enthalpy after 6 months of storage. Additionally, Gelucire 43/01™:GMO particles were produced with different mass ratios and loaded with ketoprofen. The drug loading capacity of the structured lipid carriers increased as the GMO content in the particles increased, achieving a maximum encapsulation efficiency of 97% for the 3:1 mass ratio. Moreover, structured lipid carriers presented an immediate release of ketoprofen from its matrix with higher permeation through a mucous-membrane model, while solid lipid particles present a controlled release of the drug with less permeation capacity.

  19. Structural characterization and lipid composition of acquired cholesteatoma

    DEFF Research Database (Denmark)

    Bloksgaard, Maria; Svane-Knudsen, Viggo; Sørensen, Jens A

    2012-01-01

    HYPOTHESIS: The goal of this work is to characterize the morphology and lipid composition of acquired cholesteatoma. We hypothesize that constitutive lipid membranes are present in the cholesteatoma and resemble those found in human skin stratum corneum. METHODS: We performed a comparative...... along a depth of more than 200 μm and resembles the stratum corneum of hyperorthokeratotic skin. Lipid compositional analyses of the cholesteatoma show the presence of all major lipid classes found in normal skin stratum corneum (ceramides, long chain fatty acids, and cholesterol). Consistent with this......, evaluation of Nile red and LAURDAN generalized polarization function images of the cholesteatoma show intercellular regions similar to normal skin stratum corneum in terms of lipid membrane packing and local water content. CONCLUSION: The investigations show the presence of an extremely thickened stratum...

  20. On ripples and rafts: Curvature induced nanoscale structures in lipid membranes

    Science.gov (United States)

    Schmid, Friederike; Dolezel, Stefan; Lenz, Olaf; Meinhardt, Sebastian

    2014-03-01

    We develop an elastic theory that predicts the spontaneous formation of nanoscale structures in lipid bilayers which locally phase separate between two phases with different spontaneous monolayer curvature. The theory rationalizes in a unified manner the observation of a variety of nanoscale structures in lipid membranes: Rippled states in one-component membranes, lipid rafts in multicomponent membranes. Furthermore, we report on recent observations of rippled states and rafts in simulations of a simple coarse-grained model for lipid bilayers, which are compatible with experimental observations and with our elastic model.

  1. Membrane Protein Crystallization in Lipidic Mesophases. Hosting lipid affects on the crystallization and structure of a transmembrane peptide.

    Science.gov (United States)

    Höfer, Nicole; Aragão, David; Lyons, Joseph A; Caffrey, Martin

    2011-04-06

    Gramicidin is an apolar pentadecapeptide antibiotic consisting of alternating D-and L-amino acids. It functions, in part, by creating pores in membranes of susceptible cells rendering them leaky to monovalent cations. The peptide should be able to traverse the host membrane either as a double stranded, intertwined double helix (DSDH) or as a head-to-head single stranded helix (HHSH). Current structure models are based on macromolecular X-ray crystallography (MX) and nuclear magnetic resonance (NMR). However, the HHSH form has only been observed by NMR. The shape and size of the different gramicidin conformations differ. We speculated therefore that reconstituting it into a lipidic mesophase with bilayers of different microstructures would preferentially stabilize one form over the other. By using such mesophases for in meso crystallogenesis the expectation was that at least one would generate crystals of gramicidin in the HHSH form for structure determination by MX. This was tested using commercial and in-house synthesised lipids that support in meso crystallogenesis. Lipid acyl chain lengths were varied from 14 to 18 carbons to provide mesophases with a range of bilayer thicknesses. Unexpectedly, all lipids produced high quality, structure-grade crystals with gramicidin only in the DSDH conformation.

  2. Lipid Microdomains: Structural Correlations, Fluctuations, and Formation Mechanisms

    Science.gov (United States)

    Fan, Jun; Sammalkorpi, Maria; Haataja, Mikko

    2010-03-01

    Compositional lipid microdomains (“lipid rafts”) in mammalian plasma membranes are believed to facilitate many important cellular processes. While several physically distinct scenarios predicting the presence of finite-sized microdomains in vivo have been proposed in the past, direct experimental verification or falsification of model predictions has remained elusive. Herein, we demonstrate that the combination of the spatial correlation and temporal fluctuation spectra of the lipid domains can be employed to unambiguously differentiate between the existing theoretical scenarios. Furthermore, the differentiation of the raft formation mechanisms using this methodology can be achieved by collecting data at physiologically relevant conditions without the need to tune control parameters.

  3. Dynamical clustering and a mechanism for raft-like structures in a model lipid membrane.

    Science.gov (United States)

    Starr, Francis W; Hartmann, Benedikt; Douglas, Jack F

    2014-05-01

    We use molecular dynamics simulations to examine the dynamical heterogeneity of a model single-component lipid membrane using a coarse-grained representation of lipid molecules. This model qualitatively reproduces the known phase transitions between disordered, ordered, and gel membrane phases, and the phase transitions are accompanied by significant changes in the nature of the lipid dynamics. In particular, lipid diffusion in the liquid-ordered phase is hindered by the transient trapping of molecules by their neighbors, similar to the dynamics of a liquid approaching its glass transition. This transient molecular caging gives rise to two distinct mobility groups within a single-component membrane: lipids that are transiently trapped, and lipids with displacements on the scale of the intermolecular spacing. Most significantly, lipids within these distinct mobility states spatially segregate, creating transient "islands" of enhanced mobility having a size and time scale compatible with lipid "rafts," dynamical structures thought to be important for cell membrane function. Although the dynamic lipid clusters that we observe do not themselves correspond to rafts (which are more complex, multicomponent structures), we hypothesize that such rafts may develop from the same universal mechanism, explaining why raft-like regions should arise, regardless of lipid structural or compositional details. These clusters are strikingly similar to the dynamical clusters found in glass-forming fluids, and distinct from phase-separation clusters. We also show that mobile lipid clusters can be dissected into smaller clusters of cooperatively rearranging molecules. The geometry of these clusters can be understood in the context of branched equilibrium polymers, related to percolation theory. We discuss how these dynamical structures relate to a range observations on the dynamics of lipid membranes.

  4. Influence of plasma-treatments on the structure, superstructure, and function of membrane lipids

    Science.gov (United States)

    Hammer, Malte U.; Forbrig, Enrico; Weltmann, Klaus-Dieter; Reuter, Stephan

    2012-10-01

    Every cell, eu- or prokaryotic, has a membrane as an interface to the environment. Every substance that is applied from outside the cell has to interact with it. This includes plasma-generated reactive species in the liquid cell environment created by plasma-treatment. By the Singer and Nicolson model, proteins are embedded in a lipid bilayer. Proteins are the functional elements, lipids are the structural elements. Due to the amphiphilic nature of the lipids, they form (super-) structures in an aqueous environment. The exact superstructure is determined by a structural parameter of the lipid, its shape. Here, we show experiments on lipids by fluorophore-based liposome assays and raman spectroscopy. The results show a membrane-activity of plasma-born reactive species against lipids and lipid structures. Based on this results and literature, we propose a model for a lesion-forming mechanism in membranes of some reactive species created by plasma-treatment. It is based on a hydrophobic-hydrophilic mismatch due to lipid peroxidization induced by reactive species generated in liquids by plasma-treatment.

  5. The tardigrade cuticle. I. Fine structure and the distribution of lipids.

    Science.gov (United States)

    Wright, J C

    1988-01-01

    Fine structure and lipid distribution are studied in cuticles of five tardigrade species using TEM and SEM. Double osmication using partitioning methods reveals a substantial lipid component in the intracuticle and in irregular granular regions within the procuticle. These results are substantiated by the loss of osmiophily following lipid extraction with chloroform and methanol. Other lipid components are revealed by osmication following unmasking of lipo-protein complexes with thymol. These occur in the outer epicuticle and in the trilaminar layer lying between the epi- and intracuticles. Anhydrous fixation of dehydrated tardigrades (tuns) reveals dense, superficial masses of osmiophilic material, apparently concentrated lumps of the surface mucopolysaccharide ('flocculent coat'). However, cryo-SEMs of tuns reveal similar dense aggregations which apparently exude from pores (not visible) and are removed by chloroform. These results suggest extruded lipids since the flocculent coat is unaffected by chloroform; likely functions of such lipids are discussed.

  6. Effect of gold nanoparticle on structure and fluidity of lipid membrane.

    Directory of Open Access Journals (Sweden)

    Anil R Mhashal

    Full Text Available This paper deals with the effect of different size gold nanoparticles on the fluidity of lipid membrane at different regions of the bilayer. To investigate this, we have considered significantly large bilayer leaflets and incorporated only one nanoparticle each time, which was subjected to all atomistic molecular dynamics simulations. We have observed that, lipid molecules located near to the gold nanoparticle interact directly with it, which results in deformation of lipid structure and slower dynamics of lipid molecules. However, lipid molecules far away from the interaction site of the nanoparticle get perturbed, which gives rise to increase in local ordering of the lipid domains and decrease in fluidity. The bilayer thickness and area per head group in this region also get altered. Similar trend, but with different magnitude is also observed when different size nanoparticle interact with the bilayer.

  7. Effect of Gold Nanoparticle on Structure and Fluidity of Lipid Membrane

    Science.gov (United States)

    Mhashal, Anil R.; Roy, Sudip

    2014-01-01

    This paper deals with the effect of different size gold nanoparticles on the fluidity of lipid membrane at different regions of the bilayer. To investigate this, we have considered significantly large bilayer leaflets and incorporated only one nanoparticle each time, which was subjected to all atomistic molecular dynamics simulations. We have observed that, lipid molecules located near to the gold nanoparticle interact directly with it, which results in deformation of lipid structure and slower dynamics of lipid molecules. However, lipid molecules far away from the interaction site of the nanoparticle get perturbed, which gives rise to increase in local ordering of the lipid domains and decrease in fluidity. The bilayer thickness and area per head group in this region also get altered. Similar trend, but with different magnitude is also observed when different size nanoparticle interact with the bilayer. PMID:25469786

  8. A plural role for lipids in motor neuron diseases: energy, signaling and structure.

    Directory of Open Access Journals (Sweden)

    Florent eSCHMITT

    2014-02-01

    Full Text Available Motor neuron diseases (MNDs are characterized by selective death of motor neurons and include mainly adult-onset amyotrophic lateral sclerosis (ALS and spinal muscular atrophy (SMA. Neurodegeneration is not the single pathogenic event occurring during disease progression. There are multiple lines of evidence for the existence of defects in lipid metabolism at peripheral level. For instance, hypermetabolism is well characterized in ALS, and dyslipidemia correlates with better prognosis in patients. Lipid metabolism plays also a role in other MNDs. In SMA, misuse of lipids as energetic nutrients is described in patients and in related animal models. The composition of structural lipids in the central nervous system is modified, with repercussion on membrane fluidity and on cell signaling mediated by bioactive lipids. Here, we review the main epidemiologic and mechanistic findings that link alterations of lipid metabolism and motor neuron degeneration, and we discuss the rationale of targeting these modifications for therapeutic management of MNDs.

  9. The Structure of the Mouse Serotonin 5-HT3 Receptor in Lipid Vesicles.

    Science.gov (United States)

    Kudryashev, Mikhail; Castaño-Díez, Daniel; Deluz, Cédric; Hassaine, Gherici; Grasso, Luigino; Graf-Meyer, Alexandra; Vogel, Horst; Stahlberg, Henning

    2016-01-01

    The function of membrane proteins is best understood if their structure in the lipid membrane is known. Here, we determined the structure of the mouse serotonin 5-HT3 receptor inserted in lipid bilayers to a resolution of 12 Å without stabilizing antibodies by cryo electron tomography and subtomogram averaging. The reconstruction reveals protein secondary structure elements in the transmembrane region, the extracellular pore, and the transmembrane channel pathway, showing an overall similarity to the available X-ray model of the truncated 5-HT3 receptor determined in the presence of a stabilizing nanobody. Structural analysis of the 5-HT3 receptor embedded in a lipid bilayer allowed the position of the membrane to be determined. Interactions between the densely packed receptors in lipids were visualized, revealing that the interactions were maintained by the short horizontal helices. In combination with methodological improvements, our approach enables the structural analysis of membrane proteins in response to voltage and ligand gating.

  10. Structural interactions between lipids, water and S1-S4 voltage-sensing domains.

    Science.gov (United States)

    Krepkiy, Dmitriy; Gawrisch, Klaus; Swartz, Kenton J

    2012-11-01

    Membrane proteins serve crucial signaling and transport functions, yet relatively little is known about their structures in membrane environments or how lipids interact with these proteins. For voltage-activated ion channels, X-ray structures suggest that the mobile voltage-sensing S4 helix would be exposed to the membrane, and functional studies reveal that lipid modification can profoundly alter channel activity. Here, we use solid-state NMR to investigate structural interactions of lipids and water with S1-S4 voltage-sensing domains and to explore whether lipids influence the structure of the protein. Our results demonstrate that S1-S4 domains exhibit extensive interactions with lipids and that these domains are heavily hydrated when embedded in a membrane. We also find evidence for preferential interactions of anionic lipids with S1-S4 domains and that these interactions have lifetimes on the timescale of ≤ 10(-3)s. Arg residues within S1-S4 domains are well hydrated and are positioned in close proximity to lipids, exhibiting local interactions with both lipid headgroups and acyl chains. Comparative studies with a positively charged lipid lacking a phosphodiester group reveal that this lipid modification has only modest effects on the structure and hydration of S1-S4 domains. Taken together, our results demonstrate that Arg residues in S1-S4 voltage-sensing domains reside in close proximity to the hydrophobic interior of the membrane yet are well hydrated, a requirement for carrying charge and driving protein motions in response to changes in membrane voltage.

  11. Structure characterization of phospholipids and lipid A of Pseudomonas putida KT2442.

    Science.gov (United States)

    Wang, Yuqian; Wang, Jianli; Li, Ye; Wang, Biwen; Tao, Guanjun; Wang, Xiaoyuan

    2015-01-01

    Pseudomonas putida KT2442 is an important bacterium for producing various types of polyhydroxyalkanoate polymers. Phospholipids and lipid A in membranes of P. putida play important roles in stress responses, but detailed structural information of these lipids is not known. In this study, phospholipids and lipid A were isolated from P. putida KT2442, and their structures were analyzed using thin layer chromatography, high performance liquid chromatography, and electrospray ionization/mass spectrometry. Major phospholipids in P. putida KT2442 were phosphatidylethanolamine (79.9%), phosphatidylglycero1 (12.7%), and cardiolipin (7.4%), with C16:1 and/or C18:1 acyl chains. Four lipid A species were found in P. putida KT2442: two are hexa-acylated, and the other two are penta-acylated. Compared with lipid A of P. aeruginosa, P. putida lipid A has less hydroxylation on the secondary acyl chains and less modification. Therefore, P. putida lipid A could be used as a base structure to investigate lipid A modification of P. aeruginosa for understanding its pathogenesis.

  12. Antitumor Lipids--Structure, Functions, and Medical Applications.

    Science.gov (United States)

    Kostadinova, Aneliya; Topouzova-Hristova, Tanya; Momchilova, Albena; Tzoneva, Rumiana; Berger, Martin R

    2015-01-01

    Cell proliferation and metastasis are considered hallmarks of tumor progression. Therefore, efforts have been made to develop novel anticancer drugs that inhibit both the proliferation and the motility of tumor cells. Synthetic antitumor lipids (ATLs), which are chemically divided into two main classes, comprise (i) alkylphospholipids (APLs) and (ii) alkylphosphocholines (APCs). They represent a new entity of drugs with distinct antiproliferative properties in tumor cells. These compounds do not interfere with the DNA or mitotic spindle apparatus of the cell, instead, they incorporate into cell membranes, where they accumulate and interfere with lipid metabolism and lipid-dependent signaling pathways. Recently, it has been shown that the most commonly studied APLs inhibit proliferation by inducing apoptosis in malignant cells while leaving normal cells unaffected and are potent sensitizers of conventional chemo- and radiotherapy, as well as of electrical field therapy. APLs resist catabolic degradation to a large extent, therefore accumulate in the cell and interfere with lipid-dependent survival signaling pathways, notably PI3K-Akt and Raf-Erk1/2, and de novo phospholipid biosynthesis. They are internalized in the cell membrane via raft domains and cause downstream reactions as inhibition of cell growth and migration, cell cycle arrest, actin stress fibers collapse, and apoptosis. This review summarizes the in vitro, in vivo, and clinical trials of most common ATLs and their mode of action at molecular and biochemical levels.

  13. Structuring food emulsions in the gastrointestinal tract to modify lipid digestion.

    Science.gov (United States)

    Singh, Harjinder; Ye, Aiqian; Horne, David

    2009-03-01

    The importance of nutrient lipids in the human diet has led to major advances in understanding the mechanisms of lipid digestion and absorption. With these advances has come new recognition that the matrix in which lipids are presented (i.e. food structure) in the diet could influence the rate of lipid digestion and hence the bioavailability of fatty acids. As a consequence, there is growing interest in understanding how food material properties can be manipulated under physiological conditions to control the uptake of lipids and lipid-soluble components. The lipids in many, if not most, processed foods are normally present as emulsions, which can be end products in themselves or part of a more complex food system. In this review, we discuss the formation and properties of oil-in-water (O/W) emulsions, especially how these emulsions are modified as they traverse through the gastrointestinal tract. Among other factors, the changes in the nature of the droplet adsorbed layer and the droplet size play a major role in controlling the action of lipases and lipid digestion. Greater knowledge and understanding of how the digestive system treats, transports and utilizes lipids will allow the microstructural design of foods to achieve a specific, controlled physiological response.

  14. Molecular and structural organization of lipids in foods: their fate during digestion and impact in nutrition

    Directory of Open Access Journals (Sweden)

    Meynier Anne

    2017-03-01

    Full Text Available Lipids are basic constituents of our diet. They play an active part in the acceptability, flavour and perception of our foods. At the same time, they are also regarded as beneficial for health or as sources to various pathologies. Until now, the nutritional impact of the various dietary lipid structures beyond the amounts of ingested lipids and selected fatty acids has been marginally taken into account in nutritional studies and thus in food application. This review gathers first our current knowledge on the diversity of molecular and supramolecular structures of dietary lipids, and then based on the scientific studies carried out on the human model, tempts to sum up the current knowledge and the latest hypotheses concerning the metabolic and nutritional effects of these multiscale structures. It is shown that the perception of lipids in the mouth during oral processing modulates the production of digestive fluids and food intake. Then, during the stomach and intestine phases of lipid digestion, the kinetics of release of the fatty acids are modulated by the multiscale structures of lipids influencing the fatty acid bioaccessibility and rate of absorption. In turn this may impair the post-absorption metabolism and nutritional effects. Future trends of research are evoked as concluding remarks.

  15. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    DEFF Research Database (Denmark)

    Rønnest, A. K.; Peters, Günther H.J.; Hansen, Flemming Yssing;

    2016-01-01

    the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic...... compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have...... potential within phospholipid membranes imply an enormous electric field of 108-109 V m-1, which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential...

  16. Biophysical investigations of the structure and function of the tear fluid lipid layers and the effect of ectoine. Part B: artificial lipid films.

    Science.gov (United States)

    Dwivedi, Mridula; Brinkkötter, Marc; Harishchandra, Rakesh Kumar; Galla, Hans-Joachim

    2014-10-01

    The tear fluid lipid layer is present at the outermost part of the tear film which lines the ocular surface and functions to maintain the corneal surface moist by retarding evaporation. Instability in the structure of the tear fluid lipid layer can cause an increased rate of evaporation and thus dry eye syndrome. Ectoine has been previously shown to fluidize lipid monolayers and alter the phase behavior. In the current study we have investigated the effect of ectoine on the artificial tear fluid lipid layer composed of binary and ternary lipid mixtures of dipalmitoyl phosphatidylcholine (DPPC), cholesteryl esters and tri-acyl-glycerols. The focus of our study was mainly the structural and the biophysical aspects of the artificial tear fluid lipid layer using surface activity studies and topology analysis. The presence of ectoine consistently causes an expansion of the pressure-area isotherm indicating increased intermolecular spacing. The topology studies showed the formation of droplet-like structures due to the addition of ectoine only when tri-acyl-glycerol is present in the mixture of DPPC and chol-palmitate, similar to the natural meibomian lipids. Consequently, the hypothesis of an exclusion of tri/di-acyl-glycerol from the meibomian lipid film in the presence of ectoine in the subphase is confirmed. A model describing the effect of ectoine on meibomian lipid films is further presented which may have an application for the use of ectoines in eye drops as a treatment for the dry eye syndrome.

  17. Structural diversity of archaeal ether lipid and phylogenetic relationship; Ko saikin eteru shishitsu no tayosei to keito kankei

    Energy Technology Data Exchange (ETDEWEB)

    Koga, Y. [Univ. of Occupational and Environmental Health, Kitakyushu (Japan)

    1997-05-20

    Existence of ether lipids is not limited in archaea, however, ether lipids are characteristic market of archaea. Archaeal ether lipids have diverse structures and unusual features not found in other organisms. Archaeal lipids have saturated isoprenoid hydrocarbon chain ether-linked to glycerol. Tetraether type lipids with two polar groups on two sides of hydrocarbon chains are found in archaea widely. Core lipids of non-methanogenic thermophilic archaea are mainly tetraether type lipids containing inositol as a phosphate-containing polar head group. Lipids of extreme halophilic archaea are composed of diether type and glycerophosphate as polar head groups. The feature of methanogenic archaeral lipids is nitrogen-containing polar head groups. Distribution of lipid constituents is used as a chemotaxonomic marker of extreme halophiles and methanogens. The most fundamental phenotypic difference between archaea and Eubacteria is enantiomeric difference at C-2 position of glycerophosphate backbone, that is archaea have G-1-P configuration. 31 refs., 7 figs., 3 tabs.

  18. Dynamical Clustering and the Origin of Raft-like Structures in a Model Lipid Membrane

    Science.gov (United States)

    Starr, Francis

    2014-03-01

    We investigate the dynamical heterogeneity of a model single-component lipid membrane using simulations of a coarse-grained representation of lipid molecules. In the liquid-ordered (LO) phase, lipid diffusion is hindered by the transient trapping of molecules by their neighbors, giving rise to two distinct mobility groups: low-mobility lipids which are temporarily ``caged'', and lipids with displacements on the scale of the intermolecular spacing. The lipid molecules within these distinct mobility states cluster, giving rise to transient ``islands'' of enhanced mobility having the size and time scale expected for lipid ``rafts''. These clusters are strikingly similar to the dynamical clusters found in glass-forming fluids, and distinct from phase-separation clusters. Such dynamic heterogeneity is ubiquitous in disordered condensed-phase systems. Thus, we hypothesize that rafts may originate from this universal mechanism, explaining why raft-like regions should arise, regardless of lipid structural or compositional details. This perspective provides a new approach to understand membrane transport.

  19. Reconstitution of rhodopsin into polymerizable planar supported lipid bilayers: influence of dienoyl monomer structure on photoactivation.

    Science.gov (United States)

    Subramaniam, Varuni; D'Ambruoso, Gemma D; Hall, H K; Wysocki, Ronald J; Brown, Michael F; Saavedra, S Scott

    2008-10-07

    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.

  20. Carbohydrate conformation and lipid condensation in monolayers containing glycosphingolipid Gb3: influence of acyl chain structure.

    Science.gov (United States)

    Watkins, Erik B; Gao, Haifei; Dennison, Andrew J C; Chopin, Nathalie; Struth, Bernd; Arnold, Thomas; Florent, Jean-Claude; Johannes, Ludger

    2014-09-01

    Globotriaosylceramide (Gb3), a glycosphingolipid found in the plasma membrane of animal cells, is the endocytic receptor of the bacterial Shiga toxin. Using x-ray reflectivity (XR) and grazing incidence x-ray diffraction (GIXD), lipid monolayers containing Gb3 were investigated at the air-water interface. XR probed Gb3 carbohydrate conformation normal to the interface, whereas GIXD precisely characterized Gb3's influence on acyl chain in-plane packing and area per molecule (APM). Two phospholipids, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), were used to study Gb3 packing in different lipid environments. Furthermore, the impact on monolayer structure of a naturally extracted Gb3 mixture was compared to synthetic Gb3 species with uniquely defined acyl chain structures. XR results showed that lipid environment and Gb3 acyl chain structure impact carbohydrate conformation with greater solvent accessibility observed for smaller phospholipid headgroups and long Gb3 acyl chains. In general, GIXD showed that Gb3 condensed phospholipid packing resulting in smaller APM than predicted by ideal mixing. Gb3's capacity to condense APM was larger for DSPC monolayers and exhibited different dependencies on acyl chain structure depending on the lipid environment. The interplay between Gb3-induced changes in lipid packing and the lipid environment's impact on carbohydrate conformation has broad implications for glycosphingolipid macromolecule recognition and ligand binding.

  1. Role of charged lipids in membrane structures — Insight given by simulations

    DEFF Research Database (Denmark)

    Pöyry, Sanja; Vattulainen, Ilpo

    2016-01-01

    such as phosphatidylinositols and phosphatidylserines are involved in several examples of such effects. Molecular dynamics simulations have proved an invaluable tool in exploring these aspects. This so-called computational microscope can provide both complementing explanations for the experimental results and guide experiments...... to fruitful directions. In this paper, we review studies that have utilized molecular dynamics simulations to unravel the roles of charged lipids in membrane structures. We focus on lipids as active constituents of the membranes, affecting both general membrane properties as well as non-lipid membrane...

  2. Oxidative stability of milk drinks containing structured lipids produced from sunflower oil and caprylic acid

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall;

    2003-01-01

    of adding potential antioxidants EDTA or gallic acid to the milk drink based on SL was investigated. The lipid type significantly affected the oxidative stability of the milk drinks: Milk drink based on SL oxidized faster than milk drink based on RL or SO. The reduced oxidative stability in the SL milk...... drink could not be ascribed was most likely influenced by the structure of the lipid and to a single factor, differences in the process applied to produce and purify the lipids. EDTA was a strong antioxidant, while gallic acid did not exert a distinct antioxidative effect in the milk drink based on SL....

  3. A new look at lipid-membrane structure in relation to drug research

    DEFF Research Database (Denmark)

    Mouritsen, Ole G.; Jørgensen, Kent

    1998-01-01

    Lipid-bilayer membranes are key objects in drug research in relation to (i) interaction of drugs with membrane-bound receptors, (ii) drug targeting, penetration, and permeation of cell membranes, and (iii) use of liposomes in micro-encapsulation technologies for drug delivery. Rational design...... of new drugs and drug-delivery systems therefore requries insight into the physical properties of lipid-bilayer membranes. This mini-review provides a perspective on the current view of lipid-bilayer structure and dynamics based on information obtained from a variety of recent experimental...

  4. Specific-structured lipids: nutritional perspectives and production potentials

    DEFF Research Database (Denmark)

    Xu, Xuebing; Høy, Carl-Erik; Balchen, Steen

    1997-01-01

    backbone. Recently the nutritional perspectives of this kind of lipids attract many interests. This causes an increasing interest in the production of them by lipase-catalyzed interesterification. One of the advantages of lipase method over chemical ones is that SSLs can be produced with particular fatty...... acids in specific position(s) to target specific diseases, metabolic conditions and for optimal nutrition for particular population groups. In this article, the nutritional perspectives of SSLs are reviewed and the production process by lipase-catalyzed interesterification is evaluated....

  5. Production of vegetable oil blends and structured lipids and their effect on wound healing

    Directory of Open Access Journals (Sweden)

    Juliana Neves Rodrigues Ract

    2015-06-01

    Full Text Available Two oil blends (sunflower/canola oils 85/15 (BL1 and canola/linseed oils 70/30 (BL2, were prepared and enzymatically interesterified to be applied to surgically-induced wounds in rats. Following surgery, the animals were submitted to the Treatment with Physiological Saline (TPS (control group, Blends (TBL, and Structured Lipids (TSL. The control group (TPS received physiological saline solution for 15 days. In TBL, BL1 was administered during the inflammation phase (days 0-3 and BL2 in the tissue formation and remodeling phase (days 4-15. In TSL, Structured Lipid 1 (SL1 and Structured Lipid 2 (SL2 were used instead of BL1 and BL2, respectively. The aim of this study was to compare wound closure evolution among rats treated with the blends or structured lipids versus control rats treated with physiological saline. The wound healing process was evaluated by measuring the wound areas along the treatments and the concentrations of cytokines. An increase in the areas of wounds treated with the blends and structured lipids in the inflammatory phase was observed, followed by a steeper closure curve compared to wounds treated with physiological saline. The changes observed during the inflammatory phase suggest a potential therapeutic application in cutaneous wound healing which should be further investigated.

  6. Structural determinants of protein partitioning into ordered membrane domains and lipid rafts.

    Science.gov (United States)

    Lorent, Joseph Helmuth; Levental, Ilya

    2015-11-01

    Increasing evidence supports the existence of lateral nanoscopic lipid domains in plasma membranes, known as lipid rafts. These domains preferentially recruit membrane proteins and lipids to facilitate their interactions and thereby regulate transmembrane signaling and cellular homeostasis. The functionality of raft domains is intrinsically dependent on their selectivity for specific membrane components; however, while the physicochemical determinants of raft association for lipids are known, very few systematic studies have focused on the structural aspects that guide raft partitioning of proteins. In this review, we describe biophysical and thermodynamic aspects of raft-mimetic liquid ordered phases, focusing on those most relevant for protein partitioning. Further, we detail the variety of experimental models used to study protein-raft interactions. Finally, we review the existing literature on mechanisms for raft targeting, including lipid post-translational modifications, lipid binding, and transmembrane domain features. We conclude that while protein palmitoylation is a clear raft-targeting signal, few other general structural determinants for raft partitioning have been revealed, suggesting that many discoveries lie ahead in this burgeoning field.

  7. Structure of lipid multilayers via drop casting of aqueous liposome dispersions.

    Science.gov (United States)

    Sironi, Beatrice; Snow, Tim; Redeker, Christian; Slastanova, Anna; Bikondoa, Oier; Arnold, Thomas; Klein, Jacob; Briscoe, Wuge H

    2016-05-07

    Understanding the structure of solid supported lipid multilayers is crucial to their application as a platform for novel materials. Conventionally, they are prepared from drop casting or spin coating of lipids dissolved in organic solvents, and lipid multilayers prepared from aqueous media and their structural characterisation have not been reported previously, due to their extremely low lipid solubility (i.e.∼10(-9) M) in water. Herein, using X-ray reflectivity (XRR) facilitated by a "bending mica" method, we have studied the structural characteristics of dioleoylphosphatidylcholine (DOPC) multilayers prepared via drop casting aqueous small unilamellar and multilamellar vesicle or liposome (i.e. SUV and MLV) dispersions on different surfaces, including mica, positively charged polyethylenimine (PEI) coated mica, and stearic trimethylammonium iodide (STAI) coated mica which exposes a monolayer of hydrocarbon tails. We suggest that DOPC liposomes served both as a delivery matrix where an appreciable lipid concentration in water (∼25 mg mL(-1) or 14 mM) was feasible, and as a structural precursor where the lamellar structure was readily retained on the rupture of the vesicles at the solid surface upon solvent evaporation to facilitate rapid multilayer formation. We find that multilayers on mica from MLVs exhibited polymorphism, whereas the SUV multilayers were well ordered and showed stronger stability against water. The influence of substrate chemistry (i.e. polymer coating, charge and hydrophobicity) on the multilayer structure is discussed in terms of lipid-substrate molecular interactions determining the bilayer packing proximal to the solid-liquid interface, which then had a templating effect on the structure of the bilayers distal from the interface, resulting in the overall different multilayer structural characteristics on different substrates. Such a fundamental understanding of the correlation between the physical parameters that characterise liposomes

  8. Structure of a lipid A phosphoethanolamine transferase suggests how conformational changes govern substrate binding.

    Science.gov (United States)

    Anandan, Anandhi; Evans, Genevieve L; Condic-Jurkic, Karmen; O'Mara, Megan L; John, Constance M; Phillips, Nancy J; Jarvis, Gary A; Wills, Siobhan S; Stubbs, Keith A; Moraes, Isabel; Kahler, Charlene M; Vrielink, Alice

    2017-02-28

    Multidrug-resistant (MDR) gram-negative bacteria have increased the prevalence of fatal sepsis in modern times. Colistin is a cationic antimicrobial peptide (CAMP) antibiotic that permeabilizes the bacterial outer membrane (OM) and has been used to treat these infections. The OM outer leaflet is comprised of endotoxin containing lipid A, which can be modified to increase resistance to CAMPs and prevent clearance by the innate immune response. One type of lipid A modification involves the addition of phosphoethanolamine to the 1 and 4' headgroup positions by phosphoethanolamine transferases. Previous structural work on a truncated form of this enzyme suggested that the full-length protein was required for correct lipid substrate binding and catalysis. We now report the crystal structure of a full-length lipid A phosphoethanolamine transferase from Neisseria meningitidis, determined to 2.75-Å resolution. The structure reveals a previously uncharacterized helical membrane domain and a periplasmic facing soluble domain. The domains are linked by a helix that runs along the membrane surface interacting with the phospholipid head groups. Two helices located in a periplasmic loop between two transmembrane helices contain conserved charged residues and are implicated in substrate binding. Intrinsic fluorescence, limited proteolysis, and molecular dynamics studies suggest the protein may sample different conformational states to enable the binding of two very different- sized lipid substrates. These results provide insights into the mechanism of endotoxin modification and will aid a structure-guided rational drug design approach to treating multidrug-resistant bacterial infections.

  9. Structure and distribution of the Bacillus thuringiensis Cry4Ba toxin in lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Puntheeranurak, Theeraporn [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria); Laboratory of Molecular Biophysics, Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170 (Thailand); Stroh, Cordula [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria); Zhu Rong [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria); Angsuthanasombat, Chanan [Laboratory of Molecular Biophysics, Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170 (Thailand); Hinterdorfer, Peter [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria)]. E-mail: peter.hinterdorfer@jku.at

    2005-11-15

    Bacillus thuringiensis Cry {delta}-endotoxins cause death of susceptible insect larvae by forming lytic pores in the midgut epithelial cell membranes. The 65 kDa trypsin activated Cry4Ba toxin was previously shown to be capable of permeabilizing liposomes and forming ionic channels in receptor-free planar lipid bilayers. Here, magnetic ACmode (MACmode) atomic force microscopy (AFM) was used to characterize the lateral distribution and the native molecular structure of the Cry4Ba toxin in the membrane. Liposome fusion and the Langmuir-Blodgett technique were employed for supported lipid bilayer preparations. The toxin preferentially inserted in a self-assembled structure, rather than as a single monomeric molecule. In addition, the spontaneous insertion into receptor-free lipid bilayers lead to formation of characteristic pore-like structures with four-fold symmetry, suggesting that tetramers are the preferred oligomerization state of this toxin.

  10. Low density lipoprotein: structure, dynamics, and interactions of apoB-100 with lipids

    DEFF Research Database (Denmark)

    Murtola, T.; Vuorela, T. A.; Hyvonen, M. T.;

    2011-01-01

    Low-density lipoprotein (LDL) transports cholesterol in the bloodstream and plays an important role in the development of cardiovascular diseases, in particular atherosclerosis. Despite its importance to health, the structure of LDL is not known in detail. This is worrying since the lack of LDL......'s structural information makes it more difficult to understand its function. In this work, we have combined experimental and theoretical data to construct LDL models comprised of the apoB-100 protein wrapped around a lipid droplet of about 20 nm in size. The models are considered by near-atomistic multi......-microsecond simulations to unravel structural as well as dynamical properties of LDL, with particular attention paid to lipids and their interactions with the protein. We find that the distribution and the ordering of the lipids in the LDL particle are rather complex. The previously proposed 2- and 3- layer models turn...

  11. Evidence Suggesting That Francisella tularensis O-Antigen Capsule Contains a Lipid A-Like Molecule That Is Structurally Distinct from the More Abundant Free Lipid A.

    Directory of Open Access Journals (Sweden)

    Jason H Barker

    Full Text Available Francisella tularensis, the Gram-negative bacterium that causes tularemia, produces a high molecular weight capsule that is immunologically distinct from Francisella lipopolysaccharide but contains the same O-antigen tetrasaccharide. To pursue the possibility that the capsule of Francisella live vaccine strain (LVS has a structurally unique lipid anchor, we have metabolically labeled Francisella with [14C]acetate to facilitate highly sensitive compositional analysis of capsule-associated lipids. Capsule was purified by two independent methods and yielded similar results. Autoradiographic and immunologic analysis confirmed that this purified material was largely devoid of low molecular weight LPS and of the copious amounts of free lipid A that the Francisellae accumulate. Chemical hydrolysis yielded [14C]-labeled free fatty acids characteristic of Francisella lipid A but with a different molar ratio of 3-OH C18:0 to 3-OH C16:0 and different composition of non-hydroxylated fatty acids (mainly C14:0 rather than C16:0 than that of free Francisella lipid A. Mild acid hydrolysis to induce selective cleavage of KDO-lipid A linkage yielded a [14C]-labeled product that partitioned during Bligh/Dyer extraction and migrated during thin-layer chromatography like lipid A. These findings suggest that the O-antigen capsule of Francisella contains a covalently linked and structurally distinct lipid A species. The presence of a discrete lipid A-like molecule associated with capsule raises the possibility that Francisella selectively exploits lipid A structural heterogeneity to regulate synthesis, transport, and stable bacterial surface association of the O-antigen capsular layer.

  12. Linking lipid architecture to bilayer structure and mechanics using self-consistent field modelling

    Energy Technology Data Exchange (ETDEWEB)

    Pera, H.; Kleijn, J. M.; Leermakers, F. A. M., E-mail: Frans.leermakers@wur.nl [Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6307 HB Wageningen (Netherlands)

    2014-02-14

    To understand how lipid architecture determines the lipid bilayer structure and its mechanics, we implement a molecularly detailed model that uses the self-consistent field theory. This numerical model accurately predicts parameters such as Helfrichs mean and Gaussian bending modulus k{sub c} and k{sup ¯} and the preferred monolayer curvature J{sub 0}{sup m}, and also delivers structural membrane properties like the core thickness, and head group position and orientation. We studied how these mechanical parameters vary with system variations, such as lipid tail length, membrane composition, and those parameters that control the lipid tail and head group solvent quality. For the membrane composition, negatively charged phosphatidylglycerol (PG) or zwitterionic, phosphatidylcholine (PC), and -ethanolamine (PE) lipids were used. In line with experimental findings, we find that the values of k{sub c} and the area compression modulus k{sub A} are always positive. They respond similarly to parameters that affect the core thickness, but differently to parameters that affect the head group properties. We found that the trends for k{sup ¯} and J{sub 0}{sup m} can be rationalised by the concept of Israelachivili's surfactant packing parameter, and that both k{sup ¯} and J{sub 0}{sup m} change sign with relevant parameter changes. Although typically k{sup ¯}<0, membranes can form stable cubic phases when the Gaussian bending modulus becomes positive, which occurs with membranes composed of PC lipids with long tails. Similarly, negative monolayer curvatures appear when a small head group such as PE is combined with long lipid tails, which hints towards the stability of inverse hexagonal phases at the cost of the bilayer topology. To prevent the destabilisation of bilayers, PG lipids can be mixed into these PC or PE lipid membranes. Progressive loading of bilayers with PG lipids lead to highly charged membranes, resulting in J{sub 0}{sup m}≫0, especially at low ionic

  13. Structure and Dynamics of Glycosphingolipids in Lipid Bilayers: Insights from Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Ronak Y. Patel

    2011-01-01

    Full Text Available Glycolipids are important constituents of biological membranes, and understanding their structure and dynamics in lipid bilayers provides insights into their physiological and pathological roles. Experimental techniques have provided details into their behavior at model and biological membranes; however, computer simulations are needed to gain atomic level insights. This paper summarizes the insights obtained from MD simulations into the conformational and orientational dynamics of glycosphingolipids and their exposure, hydration, and hydrogen-bonding interactions in membrane environment. The organization of glycosphingolipids in raft-like membranes and their modulation of lipid membrane structure are also reviewed.

  14. Purification of specific structured lipids by distillation: Effects on acyl migration

    DEFF Research Database (Denmark)

    Xu, Xuebing; Skands, A.; Adler-Nissen, Jens

    2001-01-01

    The cause and effects of acyl migration during the purification of specific structured lipids by distillation were studied in a conventional batch deodorizer with stripping steam. The mixture of specific structured lipids produced by lipase-catalyzed acidolysis between rapeseed oil and capric acid...... contained a large amount of free fatty acids and a small amount of partial acylglycerols besides triacylglycerols. Therefore, the effect of steam, free fatty acids, diacylglycerols, and monoacylglycerols on acyl migration was studied in a palm oil midfraction model. The results showed that all these factors...

  15. Lipid-free Apolipoprotein A-I Structure: Insights into HDL Formation and Atherosclerosis Development

    Science.gov (United States)

    Mei, Xiaohu; Atkinson, David

    2015-01-01

    Apolipoprotein A-I is the major protein in high-density lipoprotein (HDL) and plays an important role during the process of reverse cholesterol transport (RCT). Knowledge of the high-resolution structure of full-length apoA-I is vital for a molecular understanding of the function of HDL at the various steps of the RCT pathway. Due to the flexible nature of apoA-I and aggregation properties, the structure of full-length lipid-free apoA-I has evaded description for over three decades. Sequence analysis of apoA-I suggested that the amphipathic α-helix is the structural motif of exchangeable apolipoprotein, and NMR, X-ray and MD simulation studies have confirmed this. Different laboratories have used different methods to probe the secondary structure distribution and organization of both the lipid-free and lipid-bound apoA-I structure. Mutation analysis, synthetic peptide models, surface chemistry and crystal structures have converged on the lipid-free apoA-I domain structure and function: the N-terminal domain [1–184] forms a helix bundle while the C-terminal domain [185–243] mostly lacks defined structure and is responsible for initiating lipid-binding, aggregation and is also involved in cholesterol efflux. The first 43 residues of apoA-I are essential to stabilize the lipid-free structure. In addition, the crystal structure of C-terminally truncated apoA-I suggests a monomer-dimer conversation mechanism mediated through helix 5 reorganization and dimerization during the formation of HDL. Based on previous research, we have proposed a structural model for full-length monomeric apoA-I in solution and updated the HDL formation mechanism through three intermediate states. Mapping the known natural mutations on the full-length monomeric apoA-I model provides insight into atherosclerosis development through disruption of the N-terminal helix bundle or deletion of the C-terminal lipid-binding domain. PMID:26048453

  16. Biophysical investigations of the structure and function of the tear fluid lipid layer and the effect of ectoine. Part A: natural meibomian lipid films.

    Science.gov (United States)

    Dwivedi, Mridula; Backers, Hannes; Harishchandra, Rakesh Kumar; Galla, Hans-Joachim

    2014-10-01

    The tear fluid lipid layer is the outermost part of the tear film on the ocular surface which protects the eye from inflammations and injuries. We investigated the influence of ectoine on the structural organization of natural meibomian lipid films using surface activity analysis and topographical studies. These films exhibit a continuous pressure-area isotherm without any phase transition. With the addition of ectoine, the isotherm is expanded towards higher area per molecule values suggesting an increased area occupied by the interfacial lipid molecules. The AFM topology scans of natural meibomian lipid films reveal a presence of fiber-like structures. The addition of ectoine causes an appearance of droplet-like structures which are hypothesized to be tri-acyl-glycerols and other hydrophobic components excluded from the lipid film. Further the material properties of the droplet-like structure with respect to the surrounding were determined by using the quantitative imaging mode of the AFM technique. The droplet-like structures were found to be comparatively softer than the surrounding. Based on the observations a preliminary hypothesis is proposed explaining the mechanism of action of ectoine leading to the fluidization of meibomian lipid films. This suggests the possibility of ectoine as a treatment for the dry eye syndrome.

  17. Effect of emulsifier on oxidation properties of fish oil-based structured lipid emulsions.

    Science.gov (United States)

    Fomuso, Lydia B; Corredig, Milena; Akoh, Casimir C

    2002-05-08

    The effects of the emulsifiers lecithin, Tween 20, whey protein isolate, mono-/diacylglycerols, and sucrose fatty acid ester on oxidation stability of a model oil-in-water emulsion prepared with enzymatically synthesized menhaden oil-caprylic acid structured lipid were evaluated. Oxidation was monitored by measuring lipid hydroperoxides, thiobarbituric acid reactive substances, and the ratio of combined docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contents to palmitic acid in the emulsion. After high-pressure homogenization, all emulsions, except those prepared with lecithin, had similar droplet size distributions. All structured lipid emulsions, except for the lecithin-stabilized emulsions, were stable to creaming over the 48-day period studied. Emulsifier type and concentration affected oxidation rate, with 0.25% emulsifier concentration generally having a higher oxidation rate than 1% emulsifier concentration. Overall, oxidation did not progress significantly enough in 48 days of storage to affect DHA and EPA levels in the emulsion.

  18. Ether lipid generating enzyme AGPS alters the balance of structural and signaling lipids to fuel cancer pathogenicity.

    Science.gov (United States)

    Benjamin, Daniel I; Cozzo, Alyssa; Ji, Xiaodan; Roberts, Lindsay S; Louie, Sharon M; Mulvihill, Melinda M; Luo, Kunxin; Nomura, Daniel K

    2013-09-10

    Aberrant lipid metabolism is an established hallmark of cancer cells. In particular, ether lipid levels have been shown to be elevated in tumors, but their specific function in cancer remains elusive. We show here that the metabolic enzyme alkylglyceronephosphate synthase (AGPS), a critical step in the synthesis of ether lipids, is up-regulated across multiple types of aggressive human cancer cells and primary tumors. We demonstrate that ablation of AGPS in cancer cells results in reduced cell survival, cancer aggressiveness, and tumor growth through altering the balance of ether lipid, fatty acid, eicosanoid, and fatty acid-derived glycerophospholipid metabolism, resulting in an overall reduction in the levels of several oncogenic signaling lipids. Taken together, our results reveal that AGPS, in addition to maintaining ether lipids, also controls cellular utilization of fatty acids, favoring the generation of signaling lipids necessary for promoting the aggressive features of cancer.

  19. Molecular simulations of lipid systems: Edge stability and structure in pure and mixed bilayers

    Science.gov (United States)

    Jiang, Yong

    2007-12-01

    Understanding the structural, mechanical and dynamical properties of lipid self-assembled systems is fundamental to understand the behavior of the cell membrane. This thesis has investigated the equilibrium properties of lipid systems with edge defects through various molecular simulation techniques. The overall goal of this study is to understand the free energy terms of the edges and to develop efficient methods to sample equilibrium distributions of mixed-lipid systems. In the first main part of my thesis, an atomistic molecular model is used to study lipid ribbon which has two edges on both sides. Details of the edge structures, such as area per lipid and tail torsional statistics are presented. Line tension, calculated from pressure tensor in MD simulation has good agreement with result from other sources. To further investigate edge properties on a longer timescale and larger length scale, we have applied a coarse-grained forcefield on mixed lipid systems and try to interpret the edge fluctuations in terms of free energy parameters such as line tension and bending modulus. We have identified two regimes with quite different edge behavior: a high line tension regime and a low line tension regime. The last part of this thesis focuses on a hybrid Molecular dynamics and Configurational-bias Monte Carlo (MCMD) simulation method in which molecules can change their type by growing and shrinking the terminal acyl united carbon atoms. A two-step extension of the MCMD method has been developed to allow for a larger difference in the components' tail lengths. Results agreed well with previous one-step mutation results for a mixture with a length difference of four carbons. The current method can efficiently sample mixtures with a length difference of eight carbons, with a small portion of lipids of intermediate tail length. Preliminary results are obtained for "bicelle"-type (DMPC/DHPC) ribbons.

  20. Apolipoprotein E: structure and function in lipid metabolism, neurobiology, and Alzheimer's diseases.

    Science.gov (United States)

    Huang, Yadong; Mahley, Robert W

    2014-12-01

    Apolipoprotein (apo) E is a multifunctional protein with central roles in lipid metabolism, neurobiology, and neurodegenerative diseases. It has three major isoforms (apoE2, apoE3, and apoE4) with different effects on lipid and neuronal homeostasis. A major function of apoE is to mediate the binding of lipoproteins or lipid complexes in the plasma or interstitial fluids to specific cell-surface receptors. These receptors internalize apoE-containing lipoprotein particles; thus, apoE participates in the distribution/redistribution of lipids among various tissues and cells of the body. In addition, intracellular apoE may modulate various cellular processes physiologically or pathophysiologically, including cytoskeletal assembly and stability, mitochondrial integrity and function, and dendritic morphology and function. Elucidation of the functional domains within this protein and of the three-dimensional structure of the major isoforms of apoE has contributed significantly to our understanding of its physiological and pathophysiological roles at a molecular level. It is likely that apoE, with its multiple cellular origins and multiple structural and biophysical properties, is involved widely in processes of lipid metabolism and neurobiology, possibly encompassing a variety of disorders of neuronal repair, remodeling, and degeneration by interacting with different factors through various pathways.

  1. Structural insights into nonvesicular lipid transport by the oxysterol binding protein homologue family.

    Science.gov (United States)

    Tong, Junsen; Manik, Mohammad Kawsar; Yang, Huiseon; Im, Young Jun

    2016-08-01

    Sterols such as cholesterol in mammals and ergosterol in fungi are essential membrane components and play a key role in membrane function and in cell signaling. The intracellular distribution and processing of sterols and other phospholipids are in part carried out by oxysterol binding protein-related proteins (ORPs) in eukaryotes. Seven ORPs (Osh1-Osh7 proteins) in yeast have distinct functions in maintaining distribution, metabolism and signaling of intracellular lipids but they share at least one essential function. Significant progress has been made in understanding the ligand specificity and mechanism of non-vesicular lipid transport by ORPs. The unique structural features of Osh proteins explain the diversity and specificity of functions in PI(4)P-coupled lipid transport optimized in membrane contact sites. This review discusses the current advances in structural biology regarding this protein family and its potential functions, introducing them as the key players in the novel pathways of phosphoinositide-coupled directional transport of various lipids. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

  2. Structural elucidation of the interaction between neurodegenerative disease-related tau protein with model lipid membranes

    Science.gov (United States)

    Jones, Emmalee M.

    A protein's sequence of amino acids determines how it folds. That folded structure is linked to protein function, and misfolding to dysfunction. Protein misfolding and aggregation into beta-sheet rich fibrillar aggregates is connected with over 20 neurodegenerative diseases, including Alzheimer's disease (AD). AD is characterized in part by misfolding, aggregation and deposition of the microtubule associated tau protein into neurofibrillary tangles (NFTs). However, two questions remain: What is tau's fibrillization mechanism, and what is tau's cytotoxicity mechanism? Tau is prone to heterogeneous interactions, including with lipid membranes. Lipids have been found in NFTs, anionic lipid vesicles induced aggregation of the microtubule binding domain of tau, and other protein aggregates induced ion permeability in cells. This evidence prompted our investigation of tau's interaction with model lipid membranes to elucidate the structural perturbations those interactions induced in tau protein and in the membrane. We show that although tau is highly charged and soluble, it is highly surface active and preferentially interacts with anionic membranes. To resolve molecular-scale structural details of tau and model membranes, we utilized X-ray and neutron scattering techniques. X-ray reflectivity indicated tau aggregated at air/water and anionic lipid membrane interfaces and penetrated into membranes. More significantly, membrane interfaces induced tau protein to partially adopt a more compact conformation with density similar to folded protein and ordered structure characteristic of beta-sheet formation. This suggests possible membrane-based mechanisms of tau aggregation. Membrane morphological changes were seen using fluorescence microscopy, and X-ray scattering techniques showed tau completely disrupts anionic membranes, suggesting an aggregate-based cytotoxicity mechanism. Further investigation of protein constructs and a "hyperphosphorylation" disease mimic helped

  3. Lipids in the Structure of Photosystem I, Photosystem II and the Cytochrome b6f Complex

    NARCIS (Netherlands)

    Kern, Jan; Zouni, Athina; Guskov, Albert; Krauss, Norbert; Wada, Hajime; Murata, Norio

    2009-01-01

    This chapter describes the data accumulated in the last decade regarding the specific function of lipids in oxygenic photosynthesis, based on crystal structures of at least 3.0 Å resolution of the main photosynthetic membrane protein—pigment complexes, photosystem I, photosystem II and cytochrome b6

  4. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    Directory of Open Access Journals (Sweden)

    Norbert Kučerka

    2015-09-01

    Full Text Available We review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach produces robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition. From model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc..

  5. Lipids in the Structure of Photosystem I, Photosystem II and the Cytochrome b6f Complex

    NARCIS (Netherlands)

    Kern, Jan; Zouni, Athina; Guskov, Albert; Krauss, Norbert; Wada, Hajime; Murata, Norio

    2009-01-01

    This chapter describes the data accumulated in the last decade regarding the specific function of lipids in oxygenic photosynthesis, based on crystal structures of at least 3.0 Å resolution of the main photosynthetic membrane protein—pigment complexes, photosystem I, photosystem II and cytochrome

  6. Phagocytosis and killing of Candida albicans by human neutrophils after exposure to structurally different lipid emulsions.

    NARCIS (Netherlands)

    Wanten, G.J.A.; Curfs, J.H.A.J.; Meis, J.F.G.M.; Naber, A.H.J.

    2001-01-01

    BACKGROUND: To test the hypothesis that structurally different lipid emulsions have distinct immune-modulating properties, we analyzed the elimination of Candida albicans by neutrophils after exposure to various emulsions. METHODS: Neutrophils from 8 volunteers were incubated in physiologic 5 mmol/L

  7. Production of specific structured lipids by enzymatic interesterification: optimization of the reaction by response surface design

    DEFF Research Database (Denmark)

    Xu, Xuebing; Skands, Anja Rebecca Havegaard; Adler-Nissen, Jens;

    1998-01-01

    Rapeseed oil and capric acid were interesterified in solvent-free media catalyzed by Lipozyme IM (Rhizomucor miehei) to produce specific-structured lipids (SSLs). The process was optimized by response surface design concerning the effects of acyl migration and the by-products of diacylglycerols...

  8. A method for analysis of lipid vesicle domain structure from confocal image data

    DEFF Research Database (Denmark)

    Husen, Peter Rasmussen; Fidorra, Matthias; Hartel, Steffen

    2012-01-01

    Quantitative characterization of the lateral structure of curved membranes based on fluorescence microscopy requires knowledge of the fluorophore distribution on the surface. We present an image analysis approach for extraction of the fluorophore distribution on a spherical lipid vesicle from....... The analysis allows for investigation of the morphology and size distribution of domains on the surface....

  9. Structural elucidation of olive pomace fed sea bass (Dicentrarchus labrax) polar lipids with cardioprotective activities.

    Science.gov (United States)

    Nasopoulou, Constantina; Smith, Terry; Detopoulou, Maria; Tsikrika, Constantina; Papaharisis, Leonidas; Barkas, Dimitris; Zabetakis, Ioannis

    2014-02-15

    The purpose of this study was to structurally characterise the polar lipids of sea bass (Dicentrarchus labrax), fed with an experimental diet containing olive pomace (OP), that exhibit cardioprotective activities. OP has been added to conventional fish oil (FO) feed at 4% and this was the OP diet, having been supplemented as finishing diet to fish. Sea bass was aquacultured using either FO or OP diet. At the end of the dietary experiment, lipids in both samples of fish muscle were quantified and HPLC fractionated. The in vitro cardioprotective properties of the polar lipid fractions, using washed rabbit's platelets, have been assessed and the two most biologically active fractions were further analysed by mass spectrometry. The gas-chromatrograpy-mass spectrometric data shows that these two fractions contain low levels of myristic (14:0), oleic (18:1 cis ω-9) and linoleic acids (18:2 ω-6), but high levels of palmitic (16:0) and stearic acids (18:0) as well as eicosadienoic acid (20:2 ω-6). The first fraction (MS1) also contained significant levels of arachidonic acid (20:4 ω-6) and the omega-3 fatty acids: eicosapentaenoic acid (22:5) and docosahexaenoic acid (22:6). Electrospray-mass spectrometry elucidated that the lipid composition of the two fractions contained various diacyl-glycerophospholipids species, where the majority of them have either 18:0 or 18:1 fatty acids in the sn-1 position and either 22:6 or 20:2 fatty acids in the sn-2 position for MS1 and MS2, respectively. Our research focuses on the structure/function relationship of fish muscle polar lipids and cardiovascular diseases and structural data are given for polar lipid HPLC fractions with strong cardioprotective properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. The structural role of cholesterol in cell membranes: from condensed bilayers to lipid rafts.

    Science.gov (United States)

    Krause, Martin R; Regen, Steven L

    2014-12-16

    CONSPECTUS: Defining the two-dimensional structure of cell membranes represents one of the most daunting challenges currently facing chemists, biochemists, and biophysicists. In particular, the time-averaged lateral organization of the lipids and proteins that make up these natural enclosures has yet to be established. As the classic Singer-Nicolson model of cell membranes has evolved over the past 40 years, special attention has focused on the structural role played by cholesterol, a key component that represents ca. 30% of the total lipids that are present. Despite extensive studies with model membranes, two fundamental issues have remained a mystery: (i) the mechanism by which cholesterol condenses low-melting lipids by uncoiling their acyl chains and (ii) the thermodynamics of the interaction between cholesterol and high- and low-melting lipids. The latter bears directly on one of the most popular notions in modern cell biology, that is, the lipid raft hypothesis, whereby cholesterol is thought to combine with high-melting lipids to form "lipid rafts" that float in a "sea" of low-melting lipids. In this Account, we first describe a chemical approach that we have developed in our laboratories that has allowed us to quantify the interactions between exchangeable mimics of cholesterol and low- and high-melting lipids in model membranes. In essence, this "nearest-neighbor recognition" (NNR) method involves the synthesis of dimeric forms of these lipids that contain a disulfide moiety as a linker. By means of thiolate-disulfide interchange reactions, equilibrium mixtures of dimers are then formed. These exchange reactions are initiated either by adding dithiothreitol to a liposomal dispersion to generate a small amount of thiol monomer or by including a small amount of thiol monomer in the liposomes at pH 5.0 and then raising the pH to 7.4. We then show how such NNR measurements have allowed us to distinguish between two very different mechanisms that have been

  11. Oxidative stability of mayonnaise containing structured lipids produced from sunflower oil and caprylic acid

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte; Xu, Xuebing; Nielsen, Nina Skall;

    2003-01-01

    . Furthermore, the potential antioxidative effect of adding lactoferrin, propyl gallate or EDTA to the mayonnaise with SL was also investigated. Mayonnaise based on SL oxidized faster than mayonnaise based on RL or SO. The reduced oxidative stability in the SL mayonnaise could not be ascribed to a single factor......, but was most likely influenced by the structure of the lipid, the lower tocopherol content and the higher initial levels of lipid hydroperoxides and secondary volatile oxidation compounds in the SL itself compared with the RL and traditional sunflower oil employed. EDTA was a strong antioxidant, while propyl...

  12. Oxidative stability of structured lipids produced from sunflower oil and caprylic acid

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall

    2003-01-01

    and differences in production/purification, which caused lower tocopherol content and higher initial levels of primary and secondary oxidation products in SL compared with RL and SO. Grindox 117 and gallic acid did not exert a distinct antioxidative effect in the SL oil samples during storage......Traditional sunflower oil (SO), randomized lipid (RL) and specific structured lipid (SL), both produced from SO and tricaprylin/caprylic acid, respectively, were stored for up to 12 wk to compare their oxidative stabilities by chemical and sensory analyses. Furthermore, the effect of adding...

  13. Oxidative stability of mayonnaise containing structured lipids produced from sunflower oil and caprylic acid

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte; Xu, Xuebing; Nielsen, Nina Skall

    2003-01-01

    Mayonnaise based on enzymatically produced specific structured lipid (SL) from sunflower oil and caprylic acid was compared with mayonnaise based on traditional sunflower oil (SO) or chemically randomized lipid (RL) with respect to their oxidative stability, sensory and rheological properties....... Furthermore, the potential antioxidative effect of adding lactoferrin, propyl gallate or EDTA to the mayonnaise with SL was also investigated. Mayonnaise based on SL oxidized faster than mayonnaise based on RL or SO. The reduced oxidative stability in the SL mayonnaise could not be ascribed to a single factor...... gallate and lactoferrin did not exert any antioxidative effect in the SL mayonnaise...

  14. Structural characterization of lipidic systems under nonequilibrium conditions

    DEFF Research Database (Denmark)

    Yaghmur, Anan; Rappolt, Michael

    2012-01-01

    manipulation techniques including, for instance, stop-flow mixing or rapid temperature-jump perturbation is given. Second, our recent synchrotron SAXS findings on the dynamic structural response of gold nanoparticle-loaded vesicles upon exposure to an ultraviolet light source, the impact of rapidly mixing...... and the possible formation of intermediate states in the millisecond to second range. The need for investigating self-assembled systems, mainly stimuli-responsive drug nanocarriers, under nonequilibrium conditions is discussed. For pharmaceutically relevant applications, it is essential to combine...

  15. Chemically defined structured lipids: current status and future directions in gastrointestinal diseases.

    Science.gov (United States)

    Stein, J

    1999-04-01

    Over the past two decades various concepts for the supply of lipids in parenteral and enteral nutrition have been developed. Traditionally, the nutritional dietary management typically includes physical mixtures of medium chain and long-chain triglycerides. Recently, chemically defined structured lipids have been developed that combine the advantages of conventional fats with those of special purposes. The first structured lipids were produced by mixing pure medium-chain triglycerides and long-chain triglycerides, allowing hydrolysis to free fatty acids, followed by random transesterification of the fatty acids into mixed triglyceride molecules. This results in a triglyceride containing combinations of short-, medium-, and long-chain fatty acids on a single glycerol backbone. These have unique chemical, physical, and/or physiological properties which differ from simply blending mixtures from the starting fats. By use of 1,3-specific or 2-specific lipases it is now possible to synthesize 1,3-specific or 2-specific triglycerides containing short- and/or medium-chain acids. For instance, incorporation of linoleic, arachidonic, or eicosapentaenoic acid at the sn-2 position is being evaluated for the specific objective of modulating membrane fatty acid composition and essential fatty acid absorption in models of cancer, burns, and immune dysfunction. This contribution reviews the current status of experimental and clinical studies of chemically defined structured lipid-based fat emulsions, with emphasis on their therapeutic potential for nutritional support in hospitalized patients.

  16. Structural basis for self-assembly of a cytolytic pore lined by protein and lipid

    Science.gov (United States)

    Tanaka, Koji; Caaveiro, Jose M. M.; Morante, Koldo; González-Mañas, Juan Manuel; Tsumoto, Kouhei

    2015-02-01

    Pore-forming toxins (PFT) are water-soluble proteins that possess the remarkable ability to self-assemble on the membrane of target cells, where they form pores causing cell damage. Here, we elucidate the mechanism of action of the haemolytic protein fragaceatoxin C (FraC), a α-barrel PFT, by determining the crystal structures of FraC at four different stages of the lytic mechanism, namely the water-soluble state, the monomeric lipid-bound form, an assembly intermediate and the fully assembled transmembrane pore. The structure of the transmembrane pore exhibits a unique architecture composed of both protein and lipids, with some of the lipids lining the pore wall, acting as assembly cofactors. The pore also exhibits lateral fenestrations that expose the hydrophobic core of the membrane to the aqueous environment. The incorporation of lipids from the target membrane within the structure of the pore provides a membrane-specific trigger for the activation of a haemolytic toxin.

  17. Lipid Transfer Proteins As Components of the Plant Innate Immune System: Structure, Functions, and Applications.

    Science.gov (United States)

    Finkina, E I; Melnikova, D N; Bogdanov, I V; Ovchinnikova, T V

    2016-01-01

    Among a variety of molecular factors of the plant innate immune system, small proteins that transfer lipids and exhibit a broad spectrum of biological activities are of particular interest. These are lipid transfer proteins (LTPs). LTPs are interesting to researchers for three main features. The first feature is the ability of plant LTPs to bind and transfer lipids, whereby these proteins got their name and were combined into one class. The second feature is that LTPs are defense proteins that are components of plant innate immunity. The third feature is that LTPs constitute one of the most clinically important classes of plant allergens. In this review, we summarize the available data on the plant LTP structure, biological properties, diversity of functions, mechanisms of action, and practical applications, emphasizing their role in plant physiology and their significance in human life.

  18. Structural Analysis Uncovers Lipid-Binding Properties of Notch Ligands

    Directory of Open Access Journals (Sweden)

    Chandramouli R. Chillakuri

    2013-11-01

    Full Text Available The Notch pathway is a core cell-cell signaling system in metazoan organisms with key roles in cell-fate determination, stem cell maintenance, immune system activation, and angiogenesis. Signals are initiated by extracellular interactions of the Notch receptor with Delta/Serrate/Lag-2 (DSL ligands, whose structure is highly conserved throughout evolution. To date, no structure or activity has been associated with the extreme N termini of the ligands, even though numerous mutations in this region of Jagged-1 ligand lead to human disease. Here, we demonstrate that the N terminus of human Jagged-1 is a C2 phospholipid recognition domain that binds phospholipid bilayers in a calcium-dependent fashion. Furthermore, we show that this activity is shared by a member of the other class of Notch ligands, human Delta-like-1, and the evolutionary distant Drosophila Serrate. Targeted mutagenesis of Jagged-1 C2 domain residues implicated in calcium-dependent phospholipid binding leaves Notch interactions intact but can reduce Notch activation. These results reveal an important and previously unsuspected role for phospholipid recognition in control of this key signaling system.

  19. Solution synchrotron x-ray diffraction reveals structural details of lipid domains in ternary mixtures

    Science.gov (United States)

    Yuan, Jing; Kiss, Alexander; Pramudya, Yohanes H.; Nguyen, Lam T.; Hirst, Linda S.

    2009-03-01

    The influence of cholesterol on lipid bilayer structure is significant and the effect of cholesterol on lipid sorting and phase separation in lipid-raft-forming model membrane systems has been well investigated by microscopy methods on giant vesicles. An important consideration however is the influence of fluorescence illumination on the phase state of these lipids and this effect must be carefully minimized. In this paper, we show that synchrotron x-ray scattering on solution lipid mixtures is an effective alternative technique for the identification and characterization of the lo (liquid ordered) and ld (liquid disordered) phases. The high intensity of synchrotron x rays allows the observation of up to 5 orders of diffraction from the lo phase, whereas only two are clearly visible when the ld phase alone is present. This data can be collected in ˜1min/sample , allowing rapid generation of phase data. In this paper, we measure the lamellar spacing in both the liquid-ordered and liquid-disordered phases simultaneously, as a function of cholesterol concentration in two different ternary mixtures. We also observe evidence of a third gel-phaselike population at 10-12mol% cholesterol and determine the thickness of the bilayer for this phase. Importantly we are able to look at phase coexistence in the membrane independent of photoeffects.

  20. Solution Synchrotron X-ray Diffraction Reveals Structural Details of Lipid Domains in Ternary Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, J.; Kiss, A; Pramudya, Y; Nguyen, L; Hirst, L

    2009-01-01

    The influence of cholesterol on lipid bilayer structure is significant and the effect of cholesterol on lipid sorting and phase separation in lipid-raft-forming model membrane systems has been well investigated by microscopy methods on giant vesicles. An important consideration however is the influence of fluorescence illumination on the phase state of these lipids and this effect must be carefully minimized. In this paper, we show that synchrotron x-ray scattering on solution lipid mixtures is an effective alternative technique for the identification and characterization of the l o (liquid ordered) and l d (liquid disordered) phases. The high intensity of synchrotron x rays allows the observation of up to 5 orders of diffraction from the l o phase, whereas only two are clearly visible when the l d phase alone is present. This data can be collected in approximately 1 min/sample, allowing rapid generation of phase data. In this paper, we measure the lamellar spacing in both the liquid-ordered and liquid-disordered phases simultaneously, as a function of cholesterol concentration in two different ternary mixtures. We also observe evidence of a third gel-phaselike population at 10-12 mol % cholesterol and determine the thickness of the bilayer for this phase. Importantly we are able to look at phase coexistence in the membrane independent of photoeffects.

  1. Hypoxia reduces the efficiency of elisidepsin by inhibiting hydroxylation and altering the structure of lipid rafts.

    Science.gov (United States)

    Király, Anna; Váradi, Tímea; Hajdu, Tímea; Rühl, Ralph; Galmarini, Carlos M; Szöllősi, János; Nagy, Peter

    2013-12-02

    The mechanism of action of elisidepsin (PM02734, Irvalec®) is assumed to involve membrane permeabilization via attacking lipid rafts and hydroxylated lipids. Here we investigate the role of hypoxia in the mechanism of action of elisidepsin. Culturing under hypoxic conditions increased the half-maximal inhibitory concentration and decreased the drug's binding to almost all cell lines which was reversed by incubation of cells with 2-hydroxy palmitic acid. The expression of fatty acid 2-hydroxylase was strongly correlated with the efficiency of the drug and inversely correlated with the effect of hypoxia. Number and brightness analysis and fluorescence anisotropy experiments showed that hypoxia decreased the clustering of lipid rafts and altered the structure of the plasma membrane. Although the binding of elisidepsin to the membrane is non-cooperative, its membrane permeabilizing effect is characterized by a Hill coefficient of ~3.3. The latter finding is in agreement with elisidepsin-induced clusters of lipid raft-anchored GFP visualized by confocal microscopy. We propose that the concentration of elisidepsin needs to reach a critical level in the membrane above which elisidepsin induces the disruption of the cell membrane. Testing for tumor hypoxia or the density of hydroxylated lipids could be an interesting strategy to increase the efficiency of elisidepsin.

  2. Lipid memberane:inelastic deformation of surface structure by an atomic force microscope

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The stability of the 1,2-Dioleoyl-sn-Glycero-3-[phospho-rac-1-Glycerol-Na] liposome in the liquid crystalline state have been investigated using an atomic force microscope(AFM),We have observed the inelastic deformation of the sample surface,The AFM tip causes persistent deformation of the surface of the lipid membrane,in which some of the lipid molecules are eventually pushed or dragged by the AFM tip.The experiment shows how the surface structure of the lipid membrane can be created by the interaction between the AFM tip and lipid membrane.When the operating force exceeds 10-8N,it leads to large deformations of the surface.A squareregion of about 1×1um2 is created by the scanning probe on the surface,When the operating force is between 10-11N and 10-8N,it can image the topography of the surface of the lipid membrane.The stability of the sample is related to the concentration of the medium in which the sample is prepared.

  3. Plasma lipid pattern and red cell membrane structure in β-thalassemia patients in Jakarta

    Directory of Open Access Journals (Sweden)

    Seruni K.U. Freisleben

    2011-08-01

    Full Text Available Background: Over the last 10 years, we have investigated thalassemia patients in Jakarta to obtain a comprehensive picture of iron overload, oxidative stress, and cell damage.Methods: In blood samples from 15 transfusion-dependent patients (group T, 5 non-transfused patients (group N and 10 controls (group C, plasma lipids and lipoproteins, lipid-soluble vitamin E, malondialdehyde (MDA and thiol status were measured. Isolated eryhtrocyte membranes were investigated with electron paramagnetic resonance (EPR spectroscopy using doxyl-stearic acid and maleimido-proxyl spin lables. Data were analyzed statistically with ANOVA.Results: Plasma triglycerides were higher and cholesterol levels were lower in thalassemic patients compared to controls. Vitamin E, group C: 21.8 vs T: 6.2 μmol/L and reactive thiols (C: 144 vs. T: 61 μmol/L were considerably lower in transfused patients, who exert clear signs of oxidative stress (MDA, C: 1.96 vs T: 9.2 μmol/L and of tissue cell damage, i.e., high transaminases plasma levels. Non-transfused thalassemia patients have slight signs of oxidative stress, but no significant indication of cell damage. Erythrocyte membrane parameters from EPR spectroscopy differ considerably between all groups. In transfusion-dependent patients the structure of the erythrocyte membrane and the gradients of polarity and fluidity are destroyed in lipid domains; binding capacity of protein thiols in the membrane is lower and immobilized.Conclusion: In tranfusion-dependent thalassemic patients, plasma lipid pattern and oxidative stress are associated with structural damage of isolated erythrocyte membranes as measured by EPR spectroscopy with lipid and proteinthiol spin labels. (Med J Indones 2011; 20:178-84Keywords: electron paramagnetic resonance spectroscopy, erythrocyte membrane, lipoproteins, oxidative stress, thalassemia, plasma lipids.

  4. Structure-guided modification of Rhizomucor miehei lipase for production of structured lipids.

    Science.gov (United States)

    Zhang, Jun-Hui; Jiang, Yu-Yan; Lin, Ying; Sun, Yu-Fei; Zheng, Sui-Ping; Han, Shuang-Yan

    2013-01-01

    To improve the performance of yeast surface-displayed Rhizomucor miehei lipase (RML) in the production of human milk fat substitute (HMFS), we mutated amino acids in the lipase substrate-binding pocket based on protein hydrophobicity, to improve esterification activity. Five mutants: Asn87Ile, Asn87Ile/Asp91Val, His108Leu/Lys109Ile, Asp256Ile/His257Leu, and His108Leu/Lys109Ile/Asp256Ile/His257Leu were obtained and their hydrolytic and esterification activities were assayed. Using Discovery Studio 3.1 to build models and calculate the binding energy between lipase and substrates, compared to wild-type, the mutant Asp256Ile/His257Leu was found to have significantly lower energy when oleic acid (3.97 KJ/mol decrease) and tripalmitin (7.55 KJ/mol decrease) were substrates. This result was in accordance with the esterification activity of Asp256Ile/His257Leu (2.37-fold of wild-type). The four mutants were also evaluated for the production of HMFS in organic solvent and in a solvent-free system. Asp256Ile/His257Leu had an oleic acid incorporation of 28.27% for catalyzing tripalmitin and oleic acid, and 53.18% for the reaction of palm oil with oleic acid. The efficiency of Asp256Ile/His257Leu was 1.82-fold and 1.65-fold that of the wild-type enzyme for the two reactions. The oleic acid incorporation of Asp256Ile/His257Leu was similar to commercial Lipozyme RM IM for palm oil acidolysis with oleic acid. Yeast surface-displayed RML mutant Asp256Ile/His257Leu is a potential, economically feasible catalyst for the production of structured lipids.

  5. Structure-guided modification of Rhizomucor miehei lipase for production of structured lipids.

    Directory of Open Access Journals (Sweden)

    Jun-Hui Zhang

    Full Text Available To improve the performance of yeast surface-displayed Rhizomucor miehei lipase (RML in the production of human milk fat substitute (HMFS, we mutated amino acids in the lipase substrate-binding pocket based on protein hydrophobicity, to improve esterification activity. Five mutants: Asn87Ile, Asn87Ile/Asp91Val, His108Leu/Lys109Ile, Asp256Ile/His257Leu, and His108Leu/Lys109Ile/Asp256Ile/His257Leu were obtained and their hydrolytic and esterification activities were assayed. Using Discovery Studio 3.1 to build models and calculate the binding energy between lipase and substrates, compared to wild-type, the mutant Asp256Ile/His257Leu was found to have significantly lower energy when oleic acid (3.97 KJ/mol decrease and tripalmitin (7.55 KJ/mol decrease were substrates. This result was in accordance with the esterification activity of Asp256Ile/His257Leu (2.37-fold of wild-type. The four mutants were also evaluated for the production of HMFS in organic solvent and in a solvent-free system. Asp256Ile/His257Leu had an oleic acid incorporation of 28.27% for catalyzing tripalmitin and oleic acid, and 53.18% for the reaction of palm oil with oleic acid. The efficiency of Asp256Ile/His257Leu was 1.82-fold and 1.65-fold that of the wild-type enzyme for the two reactions. The oleic acid incorporation of Asp256Ile/His257Leu was similar to commercial Lipozyme RM IM for palm oil acidolysis with oleic acid. Yeast surface-displayed RML mutant Asp256Ile/His257Leu is a potential, economically feasible catalyst for the production of structured lipids.

  6. Major Lipid Body Protein: A Conserved Structural Component of Lipid Body Accumulated during Abiotic Stress in S. quadricauda CASA-CC202

    Directory of Open Access Journals (Sweden)

    Arumugam Muthu

    2016-11-01

    Full Text Available Abiotic stress in oleaginous microalgae enhances lipid accumulation and is stored in a specialised organelle called lipid droplets (LDs. Both the LDs and body are enriched with major lipid droplet protein (MLDP. It serves as a major structural component and also plays a key role in recruiting other proteins and enzymes involved in lipid body maturation. In the present study, the presence of MLDP was detected in two abiotic stress condition namely nitrogen starvation and salt stress condition. Previous research reveals that nitrogen starvation enhances lipid accumulation. Therefore, the effect of salt on growth, biomass yield, and fatty acid profile is studied in detail. The specific growth rate of S. quadricauda under the salt stress of 10mM concentration is about 0.174μ and in control, the SGR is 0.241μ. An increase in the doubling time of the cells shows that the rate of cell division decreases during salt stress (2.87–5.17. The dry biomass content also decreased drastically at 50mM salt-treated cells (129mg/L compared to control (236mg/L on the day 20. The analysis of fatty acid composition also revealed that there is a 20% decrease in the saturated fatty acid level and 19.9% increment in monounsaturated fatty acid level, which makes salt-mediated lipid accumulation as a suitable biodiesel precursor.

  7. Synthesis and in vitro transfection efficiency of spermine-based cationic lipids with different central core structures and lipophilic tails.

    Science.gov (United States)

    Niyomtham, Nattisa; Apiratikul, Nuttapon; Suksen, Kanoknetr; Opanasopit, Praneet; Yingyongnarongkul, Boon-Ek

    2015-02-01

    Twelve spermine-based cationic lipids with four different central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) and three hydrophobic tails (lauric acid, myristic acid and palmitic acid) were synthesized. The liposomes containing lipids and DOPE showed moderate to good in vitro DNA delivery into HeLa cells. GFP expression experiments revealed that liposomes composed of lipids with 3-amino-1,2-dioxypropyl as a central core structure exhibited highest transfection efficiency under serum-free condition. Whereas, lipid with 2-amino-1,3-dioxypropyl core structure showed highest transfection under 10% serum condition. Moreover, the liposomes and lipoplexes composted of these cationic lipids exhibited low cytotoxicity.

  8. Lipid membrane: inelastic deformation of surface structure by an atomic force microscope

    Institute of Scientific and Technical Information of China (English)

    张静; 孙润广

    2002-01-01

    The stability of the 1,2-Dioleoyl-sn-Glycero-3-[phospho-rac-1-Glycerol-Na] liposome in the liquid crystalline statehave been investigated using an atomic force microscope (AFM). We have observed the inelastic deformation of thesample surface. The AFM tip causes persistent deformation of the surface of the lipid membrane, in which some of thelipid molecules are eventually pushed or dragged by the AFM tip. The experiment shows how the surface structure ofthe lipid membrane can be created by the interaction between the AFM tip and lipid membrane. When the operatingforce exceeds 10-8 N, it leads to large deformations of the surface. A square region of about 1×1μm2 is created by thescanning probe on the surface. When the operating force is between 10-11N and 10-8N, it can image the topographyof the surface of the lipid membrane. The stability of the sample is related to the concentration of the medium in whichthe sample is prepared.

  9. Oxidative stability of mayonnaise and milk drink produced with structured lipids based on fish oil and caprylic acid

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall;

    2004-01-01

    The oxidative stabilities of traditional fish oil (FO), randomized lipids (RFO), or specific structured lipids (SFO) produced from fish oil were compared when incorporated into either milk drink or mayonnaise. Furthermore, the effect of adding the potential antioxidants EDTA (240 mg/kg) or lactof...

  10. Structural characterization of ether lipids from the archaeon Sulfolobus islandicus by high-resolution shotgun lipidomics

    DEFF Research Database (Denmark)

    Jensen, Sara Munk; Brandl, Martin; Treusch, Alexander H;

    2015-01-01

    -resolution Fourier transform mass spectrometry using an ion trap-orbitrap mass spectrometer. This analysis identified five clusters of molecular ions that matched ether lipids in the database with sub-ppm mass accuracy. To structurally characterize and validate the identities of the potential lipid species, we...

  11. Identification of lipid droplet structure-like/resident proteins in Caenorhabditis elegans.

    Science.gov (United States)

    Na, Huimin; Zhang, Peng; Chen, Yong; Zhu, Xiaotong; Liu, Yi; Liu, Yangli; Xie, Kang; Xu, Ningyi; Yang, Fuquan; Yu, Yong; Cichello, Simon; Mak, Ho Yi; Wang, Meng C; Zhang, Hong; Liu, Pingsheng

    2015-10-01

    The lipid droplet (LD) is a cellular organelle that stores neutral lipids in cells and has been linked with metabolic disorders. Caenorhabditis elegans has many characteristics which make it an excellent animal model for studying LDs. However, unlike in mammalian cells, no LD structure-like/resident proteins have been identified in C. elegans, which has limited the utility of this model for the study of lipid storage and metabolism. Herein based on three lines of evidence, we identified that MDT-28 and DHS-3 previously identified in C. elegans LD proteome were two LD structure-like/resident proteins. First, MDT-28 and DHS-3 were found to be the two most abundant LD proteins in the worm. Second, the proteins were specifically localized to LDs and we identified the domains responsible for this targeting in both proteins. Third and most importantly, the depletion of MDT-28 induced LD clustering while DHS-3 deletion reduced triacylglycerol content (TAG). We further characterized the proteins finding that MDT-28 was ubiquitously expressed in the intestine, muscle, hypodermis, and embryos, whereas DHS-3 was expressed mainly in intestinal cells. Together, these two LD structure-like/resident proteins provide a basis for future mechanistic studies into the dynamics and functions of LDs in C. elegans.

  12. Crystal structure of soluble MD-1 and its interaction with lipid IVa

    Science.gov (United States)

    Yoon, Sung-il; Hong, Minsun; Han, Gye Won; Wilson, Ian A.

    2010-01-01

    Lipopolysaccharide (LPS) of Gram-negative bacteria is a common pathogen-associated molecular pattern (PAMP) that induces potent innate immune responses. The host immune response against LPS is triggered by myeloid differentiation factor 2 (MD-2) in association with Toll-like receptor 4 (TLR4) on the cell surface. The MD-2/TLR4-mediated LPS response is regulated by the evolutionarily related complex of MD-1 and Toll-like receptor homolog RP105. Here, we report crystallographic and biophysical data that demonstrate a previously unidentified direct interaction of MD-1 with LPS. The crystal structure of chicken MD-1 (cMD-1) at 2.0 Å resolution exhibits a β-cup-like fold, similar to MD-2, that encloses a hydrophobic cavity between the two β-sheets. A lipid-like moiety was observed inside the cavity, suggesting the possibility of a direct MD-1/LPS interaction. LPS was subsequently identified as an MD-1 ligand by native gel electrophoresis and gel filtration analyses. The crystal structure of cMD-1 with lipid IVa, an LPS precursor, at 2.4 Å resolution revealed that the lipid inserts into the deep hydrophobic cavity of the β-cup-like structure, but with some important differences compared with MD-2. These findings suggest that soluble MD-1 alone, in addition to its complex with RP105, can regulate host LPS sensitivity. PMID:20534476

  13. Quil A-lipid powder formulations releasing ISCOMs and related colloidal structures upon hydration.

    Science.gov (United States)

    Demana, Patrick H; Davies, Nigel M; Hook, Sarah; Rades, Thomas

    2005-03-02

    The aim of the present study was to prepare solid Quil A-cholesterol-phospholipid formulations (as powder mixtures or compressed to pellets) by physical mixing or by freeze-drying of aqueous dispersions of these components in ratios that allow spontaneous formation of ISCOMs and other colloidal structures upon hydration. The effect of addition of excess cholesterol to the lipid mixtures on the release of a model antigen (PE-FITC-OVA) from the pellets was also investigated. Physical properties were evaluated by X-ray powder diffractometry (XPRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and polarized light microscopy (PLM). Characterization of aqueous colloidal dispersions was performed by negative staining transmission electron microscopy (TEM). Physically mixed powders (with or without PE-FITC-OVA) and pellets prepared from the same powders did not spontaneously form ISCOM matrices and related colloidal structures such as worm-like micelles, ring-like micelles, lipidic/layered structures and lamellae (hexagonal array of ring-like micelles) upon hydration as expected from the pseudo-ternary diagram for aqueous mixtures of Quil A, cholesterol and phospholipid. In contrast, spontaneous formation of the expected colloids was demonstrated for the freeze-dried lipid mixtures. Pellets prepared by compression of freeze-dried powders released PE-FITC-OVA slower than those prepared from physically mixed powders. TEM investigations revealed that the antigen was released in the form of colloidal particles (ISCOMs) from pellets prepared by compression of freeze-dried powders. The addition of excess cholesterol slowed down the release of antigen. The findings obtained in this study are important for the formulation of solid Quil A-containing lipid articles as controlled particulate adjuvant containing antigen delivery systems.

  14. Atomistic resolution structure and dynamics of lipid bilayers in simulations and experiments.

    Science.gov (United States)

    Ollila, O H Samuli; Pabst, Georg

    2016-10-01

    Accurate details on the sampled atomistic resolution structures of lipid bilayers can be experimentally obtained by measuring C-H bond order parameters, spin relaxation rates and scattering form factors. These parameters can be also directly calculated from the classical atomistic resolution molecular dynamics simulations (MD) and compared to the experimentally achieved results. This comparison measures the simulation model quality with respect to 'reality'. If agreement is sufficient, the simulation model gives an atomistic structural interpretation of the acquired experimental data. Significant advance of MD models is made by jointly interpreting different experiments using the same structural model. Here we focus on phosphatidylcholine lipid bilayers, which out of all model membranes have been studied mostly by experiments and simulations, leading to the largest available dataset. From the applied comparisons we conclude that the acyl chain region structure and rotational dynamics are generally well described in simulation models. Also changes with temperature, dehydration and cholesterol concentration are qualitatively correctly reproduced. However, the quality of the underlying atomistic resolution structural changes is uncertain. Even worse, when focusing on the lipid bilayer properties at the interfacial region, e.g. glycerol backbone and choline structures, and cation binding, many simulation models produce an inaccurate description of experimental data. Thus extreme care must be applied when simulations are applied to understand phenomena where the interfacial region plays a significant role. This work is done by the NMRlipids Open Collaboration project running at https://nmrlipids.blogspot.fi and https://github.com/NMRLipids. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.

  15. Cationic niosomes an effective gene carrier composed of novel spermine-derivative cationic lipids: effect of central core structures.

    Science.gov (United States)

    Opanasopit, Praneet; Leksantikul, Lalita; Niyomtham, Nattisa; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Yingyongnarongkul, Boon-Ek

    2017-05-01

    Cationic niosomes formulated from Span 20, cholesterol (Chol) and novel spermine-based cationic lipids of multiple central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) were successfully prepared for improving transfection efficiency in vitro. The niosomes composed of spermine cationic lipid with central core structure of di(oxyethyl)amino revealed the highest gene transfection efficiency. To investigate the factors affecting gene transfection and cell viability including differences in the central core structures of cationic lipids, the composition of vesicles, molar ratio of cationic lipids in formulations and the weight ratio of niosomes to DNA. Cationic niosomes composed of nonionic surfactants (Span20), cholesterol and spermine-based cationic lipids of multiple central core structures were formulated. Gene transfection and cell viability were evaluated on a human cervical carcinoma cell line (HeLa cells) using pDNA encoding green fluorescent protein (pEGFP-C2). The morphology, size and charge were also characterized. High transfection efficiency was obtained from cationic niosomes composed of Span20:Chol:cationic lipid at the molar ratio of 2.5:2.5:0.5 mM. Cationic lipids with di(oxyethyl)amino as a central core structure exhibited highest transfection efficiency. In addition, there was also no serum effect on transfection efficiency. These novel cationic niosomes may constitute a good alternative carrier for gene transfection.

  16. Oxidative stability of mayonnaise and milk drink produced with structured lipids based on fish oil and caprylic acid

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall

    2004-01-01

    The oxidative stabilities of traditional fish oil (FO), randomized lipids (RFO), or specific structured lipids (SFO) produced from fish oil were compared when incorporated into either milk drink or mayonnaise. Furthermore, the effect of adding the potential antioxidants EDTA (240 mg/kg) or lactof......The oxidative stabilities of traditional fish oil (FO), randomized lipids (RFO), or specific structured lipids (SFO) produced from fish oil were compared when incorporated into either milk drink or mayonnaise. Furthermore, the effect of adding the potential antioxidants EDTA (240 mg....../kg) or lactoferrin (1000 mg/kg) to the milk drink based on SFO was investigated. The lipid type significantly affected the oxidative stability of both mayonnaises and milk drinks: The oxidative stability decreased in the order RFO>FO>SFO. The reduced oxidative stability in the SFO food emulsions could...

  17. Specificity of Lipoprotein Chaperones for the Characteristic Lipidated Structural Motifs of their Cognate Lipoproteins.

    Science.gov (United States)

    Mejuch, Tom; van Hattum, Hilde; Triola, Gemma; Jaiswal, Mamta; Waldmann, Herbert

    2015-11-01

    Lipoprotein-binding chaperones mediate intracellular transport of lipidated proteins and determine their proper localisation and functioning. Understanding of the exact structural parameters that determine recognition and transport by different chaperones is of major interest. We have synthesised several lipid-modified peptides, representative of different lipoprotein classes, and have investigated their binding to the relevant chaperones PDEδ, UNC119a, UNC119b, and galectins-1 and -3. Our results demonstrate that PDEδ recognises S-isoprenylated C-terminal peptidic structures but not N-myristoylated peptides. In contrast, UNC119 proteins bind only mono-N-myristoylated, but do not recognise doubly lipidated and S-isoprenylated peptides at the C terminus. For galectins-1 and -3, neither binding to N-acylated, nor to C-terminally prenylated peptides could be determined. These results shed light on the specificity of the chaperone-mediated cellular lipoprotein transport systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Construction and Structural Analysis of Tethered Lipid Bilayer Containing Photosynthetic Antenna Proteins for Functional Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sumino, Ayumi; Dewa, Takehisa; Takeuchi, Toshikazu; Sugiura, Ryuta; Sasaki, Nobuaki; Misawa, Nobuo; Tero, Ryugo; Urisu, Tsuneo; Gardiner, Alastair T; Cogdell, Richard J; Hashimoto, Hideki; Nango, Mamoru

    2011-07-11

    The construction and structural analysis of a tethered planar lipid bilayer containing bacterial photosynthetic membrane proteins, light-harvesting complex 2 (LH2), and light-harvesting core complex (LH1-RC) is described and establishes this system as an experimental platform for their functional analysis. The planar lipid bilayer containing LH2 and/or LH1-RC complexes was successfully formed on an avidin-immobilized coverglass via an avidin-biotin linkage. Atomic force microscopy (AFM) showed that a smooth continuous membrane was formed there. Lateral diffusion of these membrane proteins, observed by a fluorescence recovery after photobleaching (FRAY), is discussed in terms of the membrane architecture. Energy transfer from LH2 to LH1-RC within the tethered membrane architecture. Energy transfer from LH2 to LH1-RC within the tethered membrane was observed by steady-state fluorescence spectroscopy, indicating that the tethered membrane can mimic the natural situation.

  19. Structure of the body-centered cubic phase of lipid systems.

    Science.gov (United States)

    Saludjian, P; Reiss-Husson, F

    1980-12-01

    A new model is proposed for the structure of the body-centered cubic phase of lipid systems. Infinite rods of polar groups (and water) are arranged with axes parallel to the four cubic [unk]1 1 1[unk] directions. The hydrocarbon chains fill the space between the rods to form a continuous matrix. With this unified topology, the model explains satisfactorily the x-ray diffraction patterns of strontium soaps, lecithin, galactolipids, potassium soaps, and hexadecyltrimethylammonium bromide and explains the transition between cubic/H(II) phases. The paradoxical thermal effects on the lipid cubic phase, in particular the decrease of unit cell dimensions with increasing temperature, can be explained with the proposed model by mechanisms similar to those used for the monodimensional and bidimensional (mesomorphic) phases.

  20. Effects of surface proteins and lipids on molecular structure, thermal properties, and enzymatic hydrolysis of rice starch

    Directory of Open Access Journals (Sweden)

    Pan HU

    Full Text Available Abstract Rice starches with different amylose contents were treated with sodium dodecyl sulfate (SDS to deplete surface proteins and lipids, and the changes in molecular structure, thermal properties, and enzymatic hydrolysis were evaluated. SDS treatment did not significantly change the molecular weight distribution, crystalline structure, short-range ordered degree, and gelatinization properties of starch, but significantly altered the pasting properties and increased the swelling power of starch. The removal of surface proteins and lipids increased the enzymatic hydrolysis and in vitro digestion of starch. The influences of removing surface proteins and lipids from starch on swelling power, pasting properties, and enzymatic hydrolysis were different among the various starches because of the differences in molecular structures of different starch styles. The aforementioned results indicated that removing the surface proteins and lipids from starch did not change the molecular structure but had significant effects on some functional properties.

  1. The Effect of Substrat Ratio Fish Oil and Milk Fat on Synthesis of Structured Lipid by Enzimatic Transesterification

    Directory of Open Access Journals (Sweden)

    Edy Subroto

    2013-01-01

    Full Text Available Structured lipid with saturated fatty acid (SFA at outer position and polyunsaturated fatty acid (PUFA at sn-2 position has good dietary and stabilized characteristics. In this research structured lipids was synthesized by enzymatic transesterification between fish oil and milk fat. The reaction was catalyzed by lipase from Candida antartica that has randomized specificity to inter esterification. The factor substrat ratio of fish oil and milk fat were studied. Reaction operated at 40 oC for 4 hours, and the enzim concentration was 10 % by substrat. Composition of fatty acid, regiospecificity position of fatty acid, and glyceride profile were determinate. The results showed that the substrat ratio of fish oil: milk fat affect the composition of structured lipid. The more of milk fat added showed that composition saturated fatty acids on structured lipid was increased but the unsaturated fatty acids wasdecreased. The regiospecificity of structured lipid showed that saturated fatty acid has tendency at outer position and unsaturatedfatty acid at sn-2 position and optimum at ratio fish oil: milk fat was 1 : 3 (w/w. In the ratio fish-oil: milk fat 1:3 produced structured lipids in which the sn-2 incorporated by unsaturated fatty acids such as oleic, EPA, and DHA was 22.9; 3.3, and 2.2% respectively. While in position sn-1, 3 incorporated mostly medium chain and saturated fatty acids such as capric, lauric, myristic, palmitic, and stearic acid 5.0; 7.0; 16.6; 31.7, and 9.9 % respectively. The ratio substrate did not affect the profil of glyceride on structured lipid. Triglyceride tend to decreased, and the diglyceride and monogliceride was increased with an increase of milk fat on substrate but not significantly. Structured lipid showed the characteristic like milk fat but high nutrition because rich of PUFA at sn-2 position, so this product may can applied on milk fortification.

  2. Plant lipid signaling protocols

    NARCIS (Netherlands)

    Munnik, T.; Heilmann, I.

    2013-01-01

    Eukaryotic cells are surrounded by membranes consisting of various lipids, including sterols, sphingolipids, glycolipids, and phospholipids. Besides structural functions, membranes also contain lipids with regulatory and signaling roles. Such lipids include polyphosphoinositides, the low-abundant

  3. Structured lipid emulsion as nutritional therapy for the elderly patients with severe sepsis

    Institute of Scientific and Technical Information of China (English)

    CHEN Jin; YAN Jing; CAI Guo-long; XU Qiang-hong; GONG Shi-jin; DAI Hai-wen; YU Yi-hua

    2013-01-01

    Background The nutritional support is one of the important therapeutic strategies for the elderly patients with severe sepsis,but there is controversial in choosing a parenteral nutrition formulation.This study was designed to compare the therapeutic effects of structured lipid emulsion,physically mixed medium,and long-chain fat emulsion in the treatment of severe sepsis in elderly patients.Methods A total number of 64 elder patients with severe sepsis were enrolled in the study.After a week of enteral nutritional support,the patients were randomly divided into research (structured lipid emulsion as parenteral alimentation) and control groups (physically mixed medium and long-chain fat emulsion as parenteral alimentation).The alterations of plasma albumin,lipid metabolism,and blood glucose level were recorded after parenteral alimentation and were compared between the two groups.Results The plasma levels of albumin,prealbumin,cholesterol,and triglyceride were decreased in all the patients after one week of enteral nutritional support treatment (t=7.78,P=0.000; t=10.21,P=0.000; t=7.99,P=0.000; and t=10.99,P=0.000).Further parenteral alimentation with different lipid emulsions had significant effects on the serum prealbumin and albumin (t=3.316,P=0.002; t=3.200,P=0.002),whilst had no effects on the blood glucose and triglyceride level (t=7.78,P=0.000; t=4.228,P=0.000).In addition,the two groups had a significantly different Apache Ⅱ score,ventilator time,and hospital stay time (t=-2.213,P=0.031;t=2.317,P=0.024; t=2.514,P=0.015).Conclusions The structured lipid emulsion was safe as parenteral nutrition for elderly patients with severe sepsis.It was demonstrated to be superior to the physically mixed medium and long-chain fat emulsion with respect to the protein synthesis and prognosis.

  4. Construction of Escherichia coli Mutant with Decreased Endotoxic Activity by Modifying Lipid A Structure

    Directory of Open Access Journals (Sweden)

    Qiong Liu

    2015-05-01

    Full Text Available Escherichia coli BL21 (DE3 and its derivatives are widely used for the production of recombinant proteins, but these purified proteins are always contaminated with lipopolysaccharide (LPS. LPS is recognized by the toll-like receptor 4 and myeloid differentiation factor 2 complex of mammalian immune cells and leads to release of pro-inflammatory cytokines. It is a vital step to remove LPS from the proteins before use for therapeutic purpose. In this study, we constructed BL21 (DE3 ∆msbB28 ∆pagP38 mutant, which produces a penta-acylated LPS with reduced endotoxicity. The plasmids harboring pagL and/or lpxE were then introduced into this mutant to further modify the LPS. The new strain (S004 carrying plasmid pQK004 (pagL and lpxE produced mono-phosphoryated tetra-acylated lipid A, which induces markedly less production of tumor necrosis factor-α in the RAW264.7 and IL-12 in the THP1, but still retains ability to produce recombinant proteins. This study provides a strategy to decrease endotoxic activity of recombinant proteins purified from E. coli BL21 backgrounds and a feasible approach to modify lipid A structure for alternative purposes such as mono-phosphoryl lipid A (MPL as vaccine adjuvants.

  5. The influence of amphotericin B on the molecular organization and structural properties of DPPC lipid membranes modified by sterols

    Science.gov (United States)

    Kamiński, Daniel M.; Pociecha, Damian; Górecka, Ewa; Gagoś, Mariusz

    2015-02-01

    In this work, we studied the influence of the polyene antibiotic amphotericin B (AmB) on dipalmitoylphosphatidylcholine (DPPC) multibilayers modified by cholesterol and ergosterol investigated by means of X-ray diffraction. The periodic structures related to AmB-DPPC-sterol complexes in multibilayers are completely created in temperatures above the main lipid phase transition. The differences between all observed multilayer structures are related to the thickness. Multibilayers composed of lipid and sterols have similar thickness of 51 Å. Addition of amphotericin B leads to creation of new periodic structures. Multibilayers composed of lipid-ergosterol-AmB have thickness of 44 Å which does not change with temperature. Multibilayers composed of lipid-cholesterol-AmB at 20 °C are 43 Å and gets thicker at 50 °C. Most probably this is caused by weaker van der Vaals cholesterol-amphotericin B interactions.

  6. Temperature-Dependence of Lipid A Acyl Structure in Psychrobacter cryohalolentis and Arctic Isolates of Colwellia hornerae and Colwellia piezophila

    Directory of Open Access Journals (Sweden)

    Charles R. Sweet

    2015-07-01

    Full Text Available Lipid A is a fundamental Gram-negative outer membrane component and the essential element of lipopolysaccharide (endotoxin, a potent immunostimulatory molecule. This work describes the metabolic adaptation of the lipid A acyl structure by Psychrobacter cryohalolentis at various temperatures in its facultative psychrophilic growth range, as characterized by MALDI-TOF MS and FAME GC-MS. It also presents the first elucidation of lipid A structure from the Colwellia genus, describing lipid A from strains of Colwellia hornerae and Colwellia piezophila, which were isolated as primary cultures from Arctic fast sea ice and identified by 16S rDNA sequencing. The Colwellia strains are obligate psychrophiles, with a growth range restricted to 15 °C or less. As such, these organisms have less need for fluidity adaptation in the acyl moiety of the outer membrane, and they do not display alterations in lipid A based on growth temperature. Both Psychrobacter and Colwellia make use of extensive single-methylene variation in the size of their lipid A molecules. Such single-carbon variations in acyl size were thought to be restricted to psychrotolerant (facultative species, but its presence in these Colwellia species shows that odd-chain acyl units and a single-carbon variation in lipid A structure are present in obligate psychrophiles, as well.

  7. Benefits of Structured and Free Monoacylglycerols to Deliver Eicosapentaenoic (EPA in a Model of Lipid Malabsorption

    Directory of Open Access Journals (Sweden)

    Frédéric Destaillats

    2012-11-01

    Full Text Available In the present study, we used a preclinical model of induced lipolytic enzyme insufficiency, and hypothesized that the use of monoacylglycerols (MAG will enhance their bioavailability and delivery to the tissues. Experimental diets containing 20% lipids were fed to rats for 21 days with or without Orlistat. The control diet of fish oil (FO, a source of EPA and DHA, was tested against: structured (A vanillin acetal of sn-2 MAG (Vanil + O and (B diacetyl derivative of sn-2 MAG (Acetyl + O and (C free MAG (MAG + O. FA profiles with an emphasis on EPA and DHA levels were determined in plasma, red blood cells (RBC, liver, spleen, brain and retina. We observed significant reduction of lipid absorption when rats co-consumed Orlistat. As expected, the FO groups with and without Orlistat showed the biggest difference. The Vanil + O, Acetyl + O and MAG + O groups, demonstrated higher levels of EPA (5.5 ± 1.9, 4.6 ± 1.6 and 5.6 ± 0.6, respectively in RBC compared with FO + O diets (3.3 ± 0.2, 2.6 ± 0.2. Levels of EPA incorporation, in plasma, were similar to those obtained for RBC, and similar trends were observed for the collected tissues and even with DHA levels. These observations with two MAG derivatives providing the fatty acid esterified in the sn-2 position, show that these molecules are efficient vehicles of EPA in malabsorption conditions which is in line with our hypothesis. Free MAG, characterized as having exclusively sn-1(3 isomers of EPA, demonstrated better absorption efficiencies and accretion to tissues when compared to structured MAG. The study demonstrated that structured and free MAG can be used efficiently as an enteral vehicle to supply bioactive fatty acids such as EPA and DHA in lipid malabsorption where diminished lipolytic activity is the underlying cause.

  8. Oxidation of Membrane Curvature-Regulating Phosphatidylethanolamine Lipid Results in Formation of Bilayer and Cubic Structures.

    Science.gov (United States)

    Sankhagowit, Shalene; Lee, Ernest Y; Wong, Gerard C L; Malmstadt, Noah

    2016-03-15

    Oxidation is associated with conditions related to chronic inflammations and aging. Cubic structures have been observed in the smooth endoplasmic reticulum and mitochondrial membranes of cells under oxidative stress (e.g., tumor cells and virus-infected cells). It has been previously suspected that oxidation can result in the rearrangement of lipids from a fluid lamellar phase to a cubic structure in organelles containing membranes enriched with amphiphiles that have nonzero intrinsic curvature, such as phosphatidylethanolamine (PE) and cardiolipin. This study focuses on the oxidation of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), a lipid that natively forms an inverted hexagonal phase at physiological conditions. The oxidized samples contain an approximately 3:2 molar ratio of nonoxidized to oxidized DOPE. Optical microscopy images collected during the hydration of this mixture from a dried film suggest that the system evolves into a coexistence of a stable fluid lamellar phase and transient square lattice structures with unit cell sizes of 500-600 nm. Small-angle X-ray scattering of the same lipid mixture yielded a body-centered Im3m cubic phase with the lattice parameter of 14.04 nm. On average, the effective packing parameter of the oxidized DOPE species was estimated to be 0.657 ± 0.069 (standard deviation). This suggests that the oxidation of PE leads to a group of species with inverted molecular intrinsic curvature. Oxidation can create amphiphilic subpopulations that potently impact the integrity of the membrane, since negative Gaussian curvature intrinsic to cubic phases can enable membrane destabilization processes.

  9. Effect of Receptor Structure and Length on the Wrapping of a Nanoparticle by a Lipid Membrane

    Directory of Open Access Journals (Sweden)

    Haizhen Zhang

    2014-05-01

    Full Text Available Nanoparticles have been considered as a type of powerful tool to deliver drugs and genes into cells for disease diagnosis and therapies. It has been generally accepted that the internalization of nanoparticles into cells is mostly realized by receptor-mediated endocytosis. However, for the influence of structural factors of receptors on endocytosis, this is still largely unknown. In this paper, computer simulations are applied to investigate the effects of structure (i.e., the number of constituent chains of the receptor and the length of the receptor on the wrapping behavior of nanoparticles by the lipid membrane, which is a key step of receptor-medicated endocytosis. It is found that these structural factors of receptors have strong effects on the nanoparticle’s final interaction configuration with the membrane in the simulations, such as adhering on the membrane surface or being partly or fully wrapped by the membrane. Furthermore, in some cases, the rupture of the lipid membrane occurs. These results are helpful for the understanding of endocytosis and the preparation of advanced nanoscale drug-delivery vectors.

  10. Cationic Dimyristoylphosphatidylcholine and Dioleoyloxytrimethylammonium Propane Lipid Bilayers: Atomistic Insight for Structure and Dynamics

    DEFF Research Database (Denmark)

    Zhao, W.; Gurtovenko, A. A.; Vattulainen, I.

    2012-01-01

    of 0.4, that is, at lower TAP fractions compared with saturated PC/TAP bilayers. Adding unsaturated DOTAP lipids into DMPC bilayers was found to promote lipid chain interdigitation and to fluidize lipid bilayers, as seen through enhanced lateral lipid diffusion. The speed-up in lateral diffusion...

  11. Temperature-controlled structure and kinetics of ripple phases in one- and two-component supported lipid bilayers

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Leidy, Chad; Crowe, J.H.

    2003-01-01

    ripples was seen. From height profiles of the AFM images, estimates of the amplitudes of the different ripple phases are reported. To elucidate the processes of ripple formation and disappearance, a ripple-phase DPPC lipid bilayer was taken through the pretransition in the cooling and the heating......Temperature-controlled atomic force microscopy (AFM) has been used to visualize and study the structure and kinetics of ripple phases in one-component dipalmitoylphosphaticlylcholine (DPPC) and two-component dimyristoylphosphatidylcholine-distearoylphosphatidylcholine (DMPC-DSPC) lipid bilayers....... The lipid bilayers are mica-supported double bilayers in which ripple-phase formation occurs in the top bilayer. In one-component DPPC lipid bilayers, the stable and metastable ripple phases were observed. In addition, a third ripple structure with approximately twice the wavelength of the metastable...

  12. Structure and lipid-binding properties of the kindlin-3 pleckstrin homology domain

    Science.gov (United States)

    Ni, Tao; Kalli, Antreas C.; Naughton, Fiona B.; Yates, Luke A.; Naneh, Omar; Kozorog, Mirijam; Anderluh, Gregor

    2017-01-01

    Kindlins co-activate integrins alongside talin. They possess, like talin, a FERM domain (4.1-erythrin–radixin–moiesin domain) comprising F0–F3 subdomains, but with a pleckstrin homology (PH) domain inserted in the F2 subdomain that enables membrane association. We present the crystal structure of murine kindlin-3 PH domain determined at a resolution of 2.23 Å and characterise its lipid binding using biophysical and computational approaches. Molecular dynamics simulations suggest flexibility in the PH domain loops connecting β-strands forming the putative phosphatidylinositol phosphate (PtdInsP)-binding site. Simulations with PtdInsP-containing bilayers reveal that the PH domain associates with PtdInsP molecules mainly via the positively charged surface presented by the β1–β2 loop and that it binds with somewhat higher affinity to PtdIns(3,4,5)P3 compared with PtdIns(4,5)P2. Surface plasmon resonance (SPR) with lipid headgroups immobilised and the PH domain as an analyte indicate affinities of 300 µM for PtdIns(3,4,5)P3 and 1 mM for PtdIns(4,5)P2. In contrast, SPR studies with an immobilised PH domain and lipid nanodiscs as the analyte show affinities of 0.40 µM for PtdIns(3,4,5)P3 and no affinity for PtdIns(4,5)P2 when the inositol phosphate constitutes 5% of the total lipids (∼5 molecules per nanodisc). Reducing the PtdIns(3,4,5)P3 composition to 1% abolishes nanodisc binding to the PH domain, as does site-directed mutagenesis of two lysines within the β1–β2 loop. Binding of PtdIns(3,4,5)P3 by a canonical PH domain, Grp1, is not similarly influenced by SPR experimental design. These data suggest a role for PtdIns(3,4,5)P3 clustering in the binding of some PH domains and not others, highlighting the importance of lipid mobility and clustering for the biophysical assessment of protein–membrane interactions. PMID:27974389

  13. Mass spectrometry analysis of intact Francisella bacteria identifies lipid A structure remodeling in response to acidic pH stress.

    Science.gov (United States)

    Robert, Camille B; Thomson, Michael; Vercellone, Alain; Gardner, Francesca; Ernst, Robert K; Larrouy-Maumus, Gérald; Nigou, Jérôme

    2017-08-12

    Structural modification of lipid A, the lipid anchor of LPS, is one of the strategies used by Gram-negative bacteria to evade host innate immunity. Francisella tularensis is a human pathogen that infects and replicates within phagocytic cells. It produces an atypical lipid A, whose structure precludes an efficient recognition by both innate immune players, TLR4 and cationic antimicrobial peptides. Interestingly, a recent report indicates that the lipid A of Francisella (LVS vaccinal strain) undergoes polar modifications when bacteria are grown in human macrophages as compared to in broth. To characterize the structural modifications of lipid A that may be induced intracellularly, Francisella novicida, a surrogate strain for the highly virulent F. tularensis, was submitted to different stress conditions mimicking the harsh environment encountered in the macrophages. To analyze lipid A directly from intact bacteria without any chemical treatment or purification steps, we used a rapid and sensitive MALDI-TOF mass spectrometry approach. Among the many conditions tested, only bacteria exposure to acidic pHs (from 6 to 5) induced a change in lipid A structure. These changes were characterized by an increase in the relative abundance of molecular species bearing an additional hexose unit on the diglucosamine backbone, similar to species present when bacteria are grown under reduced environmental temperature. This lipid A glyco-form, which is observed in trace amounts in normal in vitro growth conditions at 37 °C, may contribute to the intracellular parasitism of macrophages by Francisella. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  14. Suppression of acyl migration in enzymatic production of structured lipids through temperature programming

    DEFF Research Database (Denmark)

    Yang, Tiankui; Fruekilde, Maj-Britt; Xu, Xuebing

    2005-01-01

    Acyl migration in the glycerol backbone often leads to the increase of by-products in the enzymatic production of specific structured lipids. Acyl migration is a thermodynamic process and is very difficult to stop fully in actual reactions. The objective of this study was to investigate the feasi......Acyl migration in the glycerol backbone often leads to the increase of by-products in the enzymatic production of specific structured lipids. Acyl migration is a thermodynamic process and is very difficult to stop fully in actual reactions. The objective of this study was to investigate...... the feasibility of suppressing acyl migration by a programmed change of reaction temperature without loss of reaction yield. The model reactions were the acidolysis of tripalmitin with conjugated linoleic acid (CLA) or with caprylic acid (CA) targeted for human milk fat substitutes. Acyl migration...... was considerably inhibited in the temperature-programmed acidolysis of PPP with CLA or CA, with only slight reduction of acyl incorporation, the reaction leading to the required products. Acyl migration was reduced by 29% (35 h) and 45% (48 h), respectively, in the acidolysis of PPP with CLA under solvent...

  15. Crystallizing membrane proteins for structure-function studies using lipidic mesophases.

    Science.gov (United States)

    Caffrey, Martin

    2011-06-01

    The lipidic cubic phase method for crystallizing membrane proteins has posted some high-profile successes recently. This is especially true in the area of G-protein-coupled receptors, with six new crystallographic structures emerging in the last 3½ years. Slowly, it is becoming an accepted method with a proven record and convincing generality. However, it is not a method that is used in every membrane structural biology laboratory and that is unfortunate. The reluctance in adopting it is attributable, in part, to the anticipated difficulties associated with handling the sticky viscous cubic mesophase in which crystals grow. Harvesting and collecting diffraction data with the mesophase-grown crystals is also viewed with some trepidation. It is acknowledged that there are challenges associated with the method. However, over the years, we have worked to make the method user-friendly. To this end, tools for handling the mesophase in the pico- to nano-litre volume range have been developed for efficient crystallization screening in manual and robotic modes. Glass crystallization plates have been built that provide unparalleled optical quality and sensitivity to nascent crystals. Lipid and precipitant screens have been implemented for a more rational approach to crystallogenesis, such that the method can now be applied to a wide variety of membrane protein types and sizes. In the present article, these assorted advances are outlined, along with a summary of the membrane proteins that have yielded to the method. The challenges that must be overcome to develop the method further are described.

  16. Structural studies of mixed lipid bilayers on solid substrates using x-ray reflectivity

    Science.gov (United States)

    Chen, Gang; Mukhopadhyay, Mrinmay; Ma, Yicong; Sinha, Sunil; Jiang, Zhang; Decaro, Curt; Berry, Justin; Lurio, Laurence; Brozell, Adrian; Parikh, Atul

    2009-03-01

    The lipid bilayers of natural membranes generally exist in a fluid state which occurs above the gel to liquid crystalline phase transition temperature. Knowledge of the structure of such bilayers is important for understanding fundamental biological processes mediated by or occurring within membranes. We have performed systematic measurements on bilayers of 1,2-Dipalmitoyl-sn-Glycero-3-Phosphoethanolamine (DPPE) and its mixture with 1,2-Dioleoyl-sn-Glycero-3-Phosphocholine (DOPC) and cholesterol (CH) on silicon substrates with x-ray reflectivity both below and above their phase transition temperatures. Structural variations as a function of temperature are demonstrated by fitting the reflectivity data with both a model dependent and a model independent routine. Studies of Au nanoparticle labeled DOPC and DOPC + DPPE + CH mixture are also performed and the location of Au nanoparticles in these bilayers is established by analyzing the x-ray reflectivity data.

  17. Structural insights into lipid-dependent reversible dimerization of human GLTP

    Energy Technology Data Exchange (ETDEWEB)

    Samygina, Valeria R.; Ochoa-Lizarralde, Borja [CIC bioGUNE, Technology Park of Bizkaia, 48160 Derio (Spain); Popov, Alexander N. [European Synchrotron Radiation Facility, 38043 Grenoble (France); Cabo-Bilbao, Aintzane; Goni-de-Cerio, Felipe [CIC bioGUNE, Technology Park of Bizkaia, 48160 Derio (Spain); Molotkovsky, Julian G. [Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow 117997 (Russian Federation); Patel, Dinshaw J. [Memorial Sloan–Kettering Cancer Center, New York, NY 10021 (United States); Brown, Rhoderick E., E-mail: reb@umn.edu [University of Minnesota, Austin, MN 55912 (United States); Malinina, Lucy, E-mail: reb@umn.edu [CIC bioGUNE, Technology Park of Bizkaia, 48160 Derio (Spain)

    2013-04-01

    It is shown that dimerization is promoted by glycolipid binding to human GLTP. The importance of dimer flexibility in wild-type protein is manifested by point mutation that ‘locks’ the dimer while diversifying ligand/protein adaptations. Human glycolipid transfer protein (hsGLTP) forms the prototypical GLTP fold and is characterized by a broad transfer selectivity for glycosphingolipids (GSLs). The GLTP mutation D48V near the ‘portal entrance’ of the glycolipid binding site has recently been shown to enhance selectivity for sulfatides (SFs) containing a long acyl chain. Here, nine novel crystal structures of hsGLTP and the SF-selective mutant complexed with short-acyl-chain monoSF and diSF in different crystal forms are reported in order to elucidate the potential functional roles of lipid-mediated homodimerization. In all crystal forms, the hsGLTP–SF complexes displayed homodimeric structures supported by similarly organized intermolecular interactions. The dimerization interface always involved the lipid sphingosine chain, the protein C-terminus (C-end) and α-helices 6 and 2, but the D48V mutant displayed a ‘locked’ dimer conformation compared with the hinge-like flexibility of wild-type dimers. Differences in contact angles, areas and residues at the dimer interfaces in the ‘flexible’ and ‘locked’ dimers revealed a potentially important role of the dimeric structure in the C-end conformation of hsGLTP and in the precise positioning of the key residue of the glycolipid recognition centre, His140. ΔY207 and ΔC-end deletion mutants, in which the C-end is shifted or truncated, showed an almost complete loss of transfer activity. The new structural insights suggest that ligand-dependent reversible dimerization plays a role in the function of human GLTP.

  18. Homology of SMP domains to the TULIP superfamily of lipid-binding proteins provides a structural basis for lipid exchange between ER and mitochondria.

    Science.gov (United States)

    Kopec, Klaus O; Alva, Vikram; Lupas, Andrei N

    2010-08-15

    Mitochondria must uptake some phospholipids from the endoplasmic reticulum (ER) for the biogenesis of their membranes. They convert one of these lipids, phosphatidylserine, to phosphatidylethanolamine, which can be re-exported via the ER to all other cellular membranes. The mechanisms underlying these exchanges between ER and mitochondria are poorly understood. Recently, a complex termed ER-mitochondria encounter structure (ERMES) was shown to be necessary for phospholipid exchange in budding yeast. However, it is unclear whether this complex is merely an inter-organelle tether or also the transporter. ERMES consists of four proteins: Mdm10, Mdm34 (Mmm2), Mdm12 and Mmm1, three of which contain the uncharacterized SMP domain common to a number of eukaryotic membrane-associated proteins. Here, we show that the SMP domain belongs to the TULIP superfamily of lipid/hydrophobic ligand-binding domains comprising members of known structure. This relationship suggests that the SMP domains of the ERMES complex mediate lipid exchange between ER and mitochondria.

  19. Cholesterol-based cationic lipids for gene delivery: contribution of molecular structure factors to physico-chemical and biological properties.

    Science.gov (United States)

    Sheng, Ruilong; Luo, Ting; Li, Hui; Sun, Jingjing; Wang, Zhao; Cao, Amin

    2014-04-01

    In this work, we prepared a series of cholesterol-based cationic (Cho-cat) lipids bearing cholesterol hydrophobe, natural amino acid headgroups (lysine/histidine) and linkage (carbonate ester/ether) bonds. In which, the natural amino acid headgroups made dominant contribution to their physico-chemical and biological properties. Among the lipids, the l-lysine headgroup bearing lipids (Cho-es/et-Lys) showed higher pDNA binding affinity and were able to form larger sized and higher surface charged lipoplexes than that of l-histidine headgroup bearing lipids (Cho-es/et-His), they also demonstrated higher transfection efficacy and higher membrane disruption capacities than that of their l-histidine headgroup bearing counterparts. However, compared to the contributions of the headgroups, the (carbonate ester/ether) linkage bonds showed much less affects. Besides, it could be noted that, Cho-es/et-Lys lipids exhibited very high luciferase gene transfection efficiency that almost reached the transfection level of "gold standard" bPEI-25k, made them potential transfection reagents for practical application. Moreover, the results facilitated the understanding for the structure-activity relationship of the cholesterol-based cationic lipids, and also paved a simple and efficient way for achieving high transfection efficiency by modification of suitable headgroups on lipid gene carriers.

  20. Structural impact of cations on lipid bilayer models: nanomechanical properties by AFM-force spectroscopy.

    Science.gov (United States)

    Redondo-Morata, Lorena; Giannotti, Marina I; Sanz, Fausto

    2014-02-01

    Atomic Force Microscopy (AFM) has become an invaluable tool for studying the micro- and nanoworlds. As a stand-alone, high-resolution imaging technique and force transducer, it defies most other surface instrumentation in ease of use, sensitivity and versatility. The main strength of AFM relies on the possibility to operate in an aqueous environment on a wide variety of biological samples, from single molecules - DNA or proteins - to macromolecular assemblies like biological membranes. Understanding the effect of mechanical stress on membranes is of primary importance in biophysics, since cells are known to perform their function under a complex combination of forces. In the later years, AFM-based Force-Spectroscopy (AFM-FS) has provided a new vista on membrane mechanics in a confined area within the nanometer realm, where most of the specific molecular interactions take place. Lipid membranes are electrostatically charged entities that physiologically coexist with electrolyte solutions. Thus, specific interactions with ions are a matter of considerable interest. The distribution of ions in the solution and their interaction with the membranes are factors that substantially modify the structure and dynamics of the cell membranes. Furthermore, signaling processes are modified by the membrane capability of retaining ions. Supported Lipid Bilayers (SLBs) are a versatile tool to investigate phospholipid membranes mimicking biological surfaces. In the present contribution, we review selected experiments on the mechanical stability of SLBs as models of lipid membranes by means of AFM-FS, with special focus on the effect of cations and ionic strength in the overall nanomechanical stability.

  1. Lipid domain structure of the plasma membrane revealed by patching of membrane components.

    Science.gov (United States)

    Harder, T; Scheiffele, P; Verkade, P; Simons, K

    1998-05-18

    Lateral assemblies of glycolipids and cholesterol, "rafts," have been implicated to play a role in cellular processes like membrane sorting, signal transduction, and cell adhesion. We studied the structure of raft domains in the plasma membrane of non-polarized cells. Overexpressed plasma membrane markers were evenly distributed in the plasma membrane. We compared the patching behavior of pairs of raft markers (defined by insolubility in Triton X-100) with pairs of raft/non-raft markers. For this purpose we cross-linked glycosyl-phosphatidylinositol (GPI)-anchored proteins placental alkaline phosphatase (PLAP), Thy-1, influenza virus hemagglutinin (HA), and the raft lipid ganglioside GM1 using antibodies and/or cholera toxin. The patches of these raft markers overlapped extensively in BHK cells as well as in Jurkat T-lymphoma cells. Importantly, patches of GPI-anchored PLAP accumulated src-like protein tyrosine kinase fyn, which is thought to be anchored in the cytoplasmic leaflet of raft domains. In contrast patched raft components and patches of transferrin receptor as a non-raft marker were sharply separated. Taken together, our data strongly suggest that coalescence of cross-linked raft elements is mediated by their common lipid environments, whereas separation of raft and non-raft patches is caused by the immiscibility of different lipid phases. This view is supported by the finding that cholesterol depletion abrogated segregation. Our results are consistent with the view that raft domains in the plasma membrane of non-polarized cells are normally small and highly dispersed but that raft size can be modulated by oligomerization of raft components.

  2. Evidence for Lipid Packaging in the Crystal Structure of the GM2-Activator Complex with Platelet Activating Factor

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Christine S.; Mi, Li-Zhi; Rastinejad, Fraydoon (Virginia)

    2010-11-16

    GM2-activator protein (GM2-AP) is a lipid transfer protein that has the ability to stimulate the enzymatic processing of gangliosides as well as T-cell activation through lipid presentation. Our previous X-ray crystallographic studies of GM2-AP have revealed a large lipid binding pocket as the central overall feature of the structure with non-protein electron density within this pocket suggesting bound lipid. To extend these studies, we present here the 2 {angstrom} crystal structure of GM2-AP complexed with platelet activating factor (PAF). PAF is a potent phosphoacylglycerol whose toxic patho-physiological effects can be inhibited by GM2-AP. The structure shows an ordered arrangement of two bound lipids and a fatty acid molecule. One PAF molecule binds in an extended conformation within the hydrophobic channel that has an open and closed conformation, and was seen to contain bound phospholipid in the low pH apo structure. The second molecule is submerged inside the pocket in a U-shaped conformation with its head group near the single polar residue S141. It was refined as lyso-PAF as it lacks electron density for the sn-2 acetate group. The alkyl chains of PAF interact through van der Waals contacts, while the head groups bind in different environments with their phosphocholine moieties in contact with aromatic rings (Y137, F80). The structure has revealed further insights into the lipid binding properties of GM2-AP, suggesting an unexpected unique mode of lipid packaging that may explain the efficiency of GM2-AP in inhibiting the detrimental biological effects of PAF.

  3. Molecular, dynamic, and structural origin of inhomogeneous magnetization transfer in lipid membranes.

    Science.gov (United States)

    Swanson, Scott D; Malyarenko, Dariya I; Fabiilli, Mario L; Welsh, Robert C; Nielsen, Jon-Fredrik; Srinivasan, Ashok

    2017-03-01

    To elucidate the dynamic, structural, and molecular properties that create inhomogeneous magnetization transfer (ihMT) contrast. Amphiphilic lipids, lamellar phospholipids with cholesterol, and bovine spinal cord (BSC) specimens were examined along with nonlipid systems. Magnetization transfer (MT), enhanced MT (eMT, obtained with double-sided radiofrequency saturation), ihMT (MT - eMT), and dipolar relaxation, T1D , were measured at 2.0 and 11.7 T. The amplitude of ihMT ratio (ihMTR) is positively correlated with T1D values. Both ihMTR and T1D increase with increasing temperature in BSC white matter and in phospholipids and decrease with temperature in other lipids. Changes in ihMTR with temperature arise primarily from alterations in MT rather than eMT. Spectral width of MT, eMT, and ihMT increases with increasing carbon chain length. Concerted motions of phospholipids in white matter decrease proton spin diffusion leading to increased proton T1D times and increased ihMT amplitudes, consistent with decoupling of Zeeman and dipolar spin reservoirs. Molecular specificity and dynamic sensitivity of ihMT contrast make it a suitable candidate for probing myelin membrane disorders. Magn Reson Med 77:1318-1328, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  4. Oxidative fate of lipid structures in food and during digestion – possible metabolic significance

    OpenAIRE

    Genot, Claude; Kenmogne Domguia , Hernan; Michalski, Marie-Caroline; Awada, Manar; Meynier, Anne

    2011-01-01

    Although excessive lipid consumption should be avoided, dietary lipids are now recognized as having various beneficial nutritional effects, especially regarding the need for a balanced supply in both omega-6 and omega-3 polyunsaturated fatty acids (PUFA). Improving the lipid profiles through an increase of PUFA supply also increases risks of (per)oxidation with possible negative consequences for food technological, sensory and nutritional properties. Food lipids exhibit various molecular and ...

  5. Structural basis for feed-forward transcriptional regulation of membrane lipid homeostasis in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Daniela Albanesi

    2013-01-01

    Full Text Available The biosynthesis of membrane lipids is an essential pathway for virtually all bacteria. Despite its potential importance for the development of novel antibiotics, little is known about the underlying signaling mechanisms that allow bacteria to control their membrane lipid composition within narrow limits. Recent studies disclosed an elaborate feed-forward system that senses the levels of malonyl-CoA and modulates the transcription of genes that mediate fatty acid and phospholipid synthesis in many Gram-positive bacteria including several human pathogens. A key component of this network is FapR, a transcriptional regulator that binds malonyl-CoA, but whose mode of action remains enigmatic. We report here the crystal structures of FapR from Staphylococcus aureus (SaFapR in three relevant states of its regulation cycle. The repressor-DNA complex reveals that the operator binds two SaFapR homodimers with different affinities, involving sequence-specific contacts from the helix-turn-helix motifs to the major and minor grooves of DNA. In contrast with the elongated conformation observed for the DNA-bound FapR homodimer, binding of malonyl-CoA stabilizes a different, more compact, quaternary arrangement of the repressor, in which the two DNA-binding domains are attached to either side of the central thioesterase-like domain, resulting in a non-productive overall conformation that precludes DNA binding. The structural transition between the DNA-bound and malonyl-CoA-bound states of SaFapR involves substantial changes and large (>30 Å inter-domain movements; however, both conformational states can be populated by the ligand-free repressor species, as confirmed by the structure of SaFapR in two distinct crystal forms. Disruption of the ability of SaFapR to monitor malonyl-CoA compromises cell growth, revealing the essentiality of membrane lipid homeostasis for S. aureus survival and uncovering novel opportunities for the development of antibiotics

  6. Structural basis for feed-forward transcriptional regulation of membrane lipid homeostasis in Staphylococcus aureus.

    Science.gov (United States)

    Albanesi, Daniela; Reh, Georgina; Guerin, Marcelo E; Schaeffer, Francis; Debarbouille, Michel; Buschiazzo, Alejandro; Schujman, Gustavo E; de Mendoza, Diego; Alzari, Pedro M

    2013-01-01

    The biosynthesis of membrane lipids is an essential pathway for virtually all bacteria. Despite its potential importance for the development of novel antibiotics, little is known about the underlying signaling mechanisms that allow bacteria to control their membrane lipid composition within narrow limits. Recent studies disclosed an elaborate feed-forward system that senses the levels of malonyl-CoA and modulates the transcription of genes that mediate fatty acid and phospholipid synthesis in many Gram-positive bacteria including several human pathogens. A key component of this network is FapR, a transcriptional regulator that binds malonyl-CoA, but whose mode of action remains enigmatic. We report here the crystal structures of FapR from Staphylococcus aureus (SaFapR) in three relevant states of its regulation cycle. The repressor-DNA complex reveals that the operator binds two SaFapR homodimers with different affinities, involving sequence-specific contacts from the helix-turn-helix motifs to the major and minor grooves of DNA. In contrast with the elongated conformation observed for the DNA-bound FapR homodimer, binding of malonyl-CoA stabilizes a different, more compact, quaternary arrangement of the repressor, in which the two DNA-binding domains are attached to either side of the central thioesterase-like domain, resulting in a non-productive overall conformation that precludes DNA binding. The structural transition between the DNA-bound and malonyl-CoA-bound states of SaFapR involves substantial changes and large (>30 Å) inter-domain movements; however, both conformational states can be populated by the ligand-free repressor species, as confirmed by the structure of SaFapR in two distinct crystal forms. Disruption of the ability of SaFapR to monitor malonyl-CoA compromises cell growth, revealing the essentiality of membrane lipid homeostasis for S. aureus survival and uncovering novel opportunities for the development of antibiotics against this major human

  7. Structural analysis of bacteriorhodopsin solubilized by lipid-like phosphocholine biosurfactants with varying micelle concentrations.

    Science.gov (United States)

    Wang, Xiaoqiang; Huang, Haihong; Sun, Chenghao; Huang, Fang

    2015-01-01

    Surfactants that can provide a more natural substitute for lipid bilayers are important in the purification and in vitro study of membrane proteins. Here we investigate the structural response of a model membrane protein, bacteriorhodopsin (BR), to phosphocholine biosurfactants. Phosphocholine biosurfactants are a type of biomimetic amphiphile that are similar to phospholipids, in which membrane proteins are commonly embedded. Multiple spectroscopic and zeta potential measurements are employed to characterize the conformational change, secondary and tertiary structure, oligomeric status, surface charge distribution and the structural stability of BR solubilized with phosphocholine biosurfactants of varying tail length. The process of phosphocholine micelle formation is found to facilitate the solubilization of BR, and for long-chain phosphocholines, concentrations much higher than their critical micelle concentrations achieve good solubilization. Phosphocholine biosurfactants are shown to be mild compared with the ionic surfactant SDS or CTAB, and tend to preserve membrane protein structure during solubilization, especially at low micelle concentrations, by virtue of their phospholipid-like zwitterionic head groups. The increase of alkyl chain length is shown to obviously enhance the capability of phosphocholine biosurfactants to stabilize BR. The underlying mechanism for the favorable actions of phosphocholine biosurfactant is also discussed.

  8. Application of antioxidants during short-path distillation of structured lipids

    DEFF Research Database (Denmark)

    Timm-Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall

    2007-01-01

    A specific structured lipid was produced from sunflower oil and caprylic acid. The antioxidative effect of adding alpha-tocopherol, ascorbyl palmitate or citric acid (each in three different concentrations) was investigated before and after the purification process (short-path distillation......), and was compared with a control without addition of antioxidant. The oxidative status and stability were characterized by peroxide and anisidine values, secondary volatile oxidation products and induction period. The antioxidants affected the oxidative status compared with the control: citric acid was prooxidative...... at low concentrations, but antioxidative at high concentrations. Addition of ascorbyl palmitate had an antioxidative effect at all concentrations employed. alpha-Tocopherol showed less antioxidative activity compared with ascorbyl palmitate and citric acid, and its efficacy was slightly decreased...

  9. Production of specifically structured lipids by enzymatic interesterification in a pilot enzyme bed reactor: process optimization by response surface methodology

    DEFF Research Database (Denmark)

    Xu, Xuebing; Mu, Huiling; Høy, Carl-Erik;

    1999-01-01

    Pilot production of specifically structured lipids by Lipozyme IM-catalyzed interesterification was carried out in a continuous enzyme bed reactor without the use of solvent. Medium chain triacylglycerols and oleic acid were used as model substrates. Response surface methodology was applied...... and the production of mono-incorporated and di-incorporated structured lipids with multiple regression and backward elimination. The coefficient of determination (R2) for the incorporation was 0.93, and that for the di-incorporated products was 0.94. The optimal conditions were flow rate, 2 ml/min; temperature, 65...

  10. HAMLET interacts with lipid membranes and perturbs their structure and integrity.

    Science.gov (United States)

    Mossberg, Ann-Kristin; Puchades, Maja; Halskau, Øyvind; Baumann, Anne; Lanekoff, Ingela; Chao, Yinxia; Martinez, Aurora; Svanborg, Catharina; Karlsson, Roger

    2010-02-23

    Cell membrane interactions rely on lipid bilayer constituents and molecules inserted within the membrane, including specific receptors. HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a tumoricidal complex of partially unfolded alpha-lactalbumin (HLA) and oleic acid that is internalized by tumor cells, suggesting that interactions with the phospholipid bilayer and/or specific receptors may be essential for the tumoricidal effect. This study examined whether HAMLET interacts with artificial membranes and alters membrane structure. We show by surface plasmon resonance that HAMLET binds with high affinity to surface adherent, unilamellar vesicles of lipids with varying acyl chain composition and net charge. Fluorescence imaging revealed that HAMLET accumulates in membranes of vesicles and perturbs their structure, resulting in increased membrane fluidity. Furthermore, HAMLET disrupted membrane integrity at neutral pH and physiological conditions, as shown by fluorophore leakage experiments. These effects did not occur with either native HLA or a constitutively unfolded Cys-Ala HLA mutant (rHLA(all-Ala)). HAMLET also bound to plasma membrane vesicles formed from intact tumor cells, with accumulation in certain membrane areas, but the complex was not internalized by these vesicles or by the synthetic membrane vesicles. The results illustrate the difference in membrane affinity between the fatty acid bound and fatty acid free forms of partially unfolded HLA and suggest that HAMLET engages membranes by a mechanism requiring both the protein and the fatty acid. Furthermore, HAMLET binding alters the morphology of the membrane and compromises its integrity, suggesting that membrane perturbation could be an initial step in inducing cell death.

  11. Solvent-free enzymatic synthesis of feruloylated structured lipids by the transesterification of ethyl ferulate with castor oil.

    Science.gov (United States)

    Sun, Shangde; Zhu, Sha; Bi, Yanlan

    2014-09-01

    A novel enzymatic route of feruloylated structured lipids synthesis by the transesterification of ethyl ferulate (EF) with castor oil, in solvent-free system, was investigated. The transesterification reactions were catalysed by Novozym 435, Lipozyme RMIM, and Lipozyme TLIM, among which Novozym 435 showed the best catalysis performance. Effects of feruloyl donors, reaction variables, and ethanol removal on the transesterification were also studied. High EF conversion (∼100%) was obtained under the following conditions: enzyme load 20% (w/w, relative to the weight of substrates), reaction temperature 90 °C, substrate molar ratio 1:1 (EF/castor oil), 72 h, vacuum pressure 10 mmHg, and 200 rpm. Under these conditions, the transesterification product consisted of 62.6% lipophilic feruloylated structured lipids and 37.3% hydrophilic feruloylated lipids.

  12. Structural Dynamics of the Magnesium-bound Conformation of CorA in a lipid bilayer

    Science.gov (United States)

    Dalmas, Olivier; Cuello, Luis G.; Jogini, Vishwanath; Cortes, D. Marien; Roux, Benoit; Perozo, Eduardo

    2010-01-01

    Summary The transmembrane conformation of Thermotoga maritima CorA, a Magnesium transport system, has been studied in it’s Mg2+-bound form by site-directed spin labeling and electron paramagnetic resonance spectroscopy. Probe mobility together with accessibility data were used to evaluate the overall dynamics and relative arrangement of individual transmembrane segments TM1 and TM2. TM1 extends toward the cytoplasmic side creating a water filled cavity, while TM2 is located in the periphery of the oligomer, contacting the lipid bilayer. A structural model for the conserved extracellular loop was generated based on EPR data and MD simulations, in which residue E316 is located towards the fivefold symmetry axis in position to electrostatically influence divalent ion translocation. Electrostatic analyses of our model suggest that, in agreement with the crystal structure, Mg2+ -bound CorA is in a close conformation. The present results suggest that long-range structural rearrangements are necessary to allow Mg2+ translocation. PMID:20637423

  13. Structural dynamics of the magnesium-bound conformation of CorA in a lipid bilayer.

    Science.gov (United States)

    Dalmas, Olivier; Cuello, Luis G; Jogini, Vishwanath; Cortes, D Marien; Roux, Benoit; Perozo, Eduardo

    2010-07-14

    The transmembrane conformation of Thermotoga maritima CorA, a magnesium transport system, has been studied in its Mg(2+)-bound form by site-directed spin labeling and electron paramagnetic resonance spectroscopy. Probe mobility together with accessibility data were used to evaluate the overall dynamics and relative arrangement of individual transmembrane segments TM1 and TM2. TM1 extends toward the cytoplasmic side creating a water-filled cavity, while TM2 is located in the periphery of the oligomer, contacting the lipid bilayer. A structural model for the conserved extracellular loop was generated based on EPR data and MD simulations, in which residue E316 is located toward the five-fold symmetry axis in position to electrostatically influence divalent ion translocation. Electrostatic analysis of our model suggest that, in agreement with the crystal structure, Mg(2+) -bound CorA is in a closed conformation. The present results suggest that long-range structural rearrangements are necessary to allow Mg(2+) translocation. Copyright 2010 Elsevier Ltd. All rights reserved.

  14. Structural basis for the recognition of peptide RJPXD33 by acyltransferases in lipid A biosynthesis.

    Science.gov (United States)

    Jenkins, Ronald J; Heslip, Kyle A; Meagher, Jennifer L; Stuckey, Jeanne A; Dotson, Garry D

    2014-05-30

    UDP-N-acetylglucosamine acyltransferase (LpxA) and UDP-3-O-(acyl)-glucosamine acyltransferase (LpxD) constitute the essential, early acyltransferases of lipid A biosynthesis. Recently, an antimicrobial peptide inhibitor, RJPXD33, was identified with dual affinity for LpxA and LpxD. To gain a fundamental understanding of the molecular basis of inhibitor binding, we determined the crystal structure of LpxA from Escherichia coli in complex with RJPXD33 at 1.9 Å resolutions. Our results suggest that the peptide binds in a unique modality that mimics (R)-β-hydroxyacyl pantetheine binding to LpxA and displays how the peptide binds exclusive of the native substrate, acyl-acyl carrier protein. Acyltransferase binding studies with photo-labile RJPXD33 probes and truncations of RJPXD33 validated the structure and provided fundamental insights for future design of small molecule inhibitors. Overlay of the LpxA-RJPXD33 structure with E. coli LpxD identified a complementary peptide binding pocket within LpxD and serves as a model for further biochemical characterization of RJPXD33 binding to LpxD. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Fourier-transform infrared spectroscopic studies on avidin secondary structure and complexation with biotin and biotin-lipid assemblies.

    Science.gov (United States)

    Swamy, M J; Heimburg, T; Marsh, D

    1996-08-01

    Fourier-transform infrared studies have been carried out to investigate the secondary structure and thermal stability of hen egg white avidin and its complexes with biotin and with a biotinylated lipid derivative, N-biotinyl dimyristoyl phosphatidylethanolamine (DMBPE) in aqueous dispersion. Analysis of the amide I stretching band of avidin yielded a secondary structural content composed of approximately 66% beta-sheet and extended structures, with the remainder being attributed to disordered structure and beta-turns. Binding of biotin or specific association with the biotinylated lipid DMBPE did not result in any appreciable changes in the secondary structure content of the protein, but a change in hydrogen bond stability of the beta-sheet or extended chain regions was indicated. The latter effect was enhanced by surface interactions in the case of the biotin-lipid assemblies, as was demonstrated by electrostatic binding to a nonspecific negatively charged lipid. Difference spectra of the bound biotin implicated a direct involvement of the ureido moiety in the ligand interaction that was consistent with hydrogen bonding to amino acid residues in the avidin protein. It was found that complexation with avidin leads to a decrease in bond length of the biotin ureido carbonyl group that is consistent with a reduction of sp3 character of the C-O bond when it is hydrogen bonded to the protein. Studies of the temperature dependence of the spectra revealed that for avidin alone the secondary structure was unaltered up to approximately 75 degrees C, above which the protein undergoes a highly cooperative transition to an unfolded state with concomitant loss of ordered secondary structure. The complexes of avidin with both biotin and membrane-bound DMBPE lipid assemblies display a large increase in thermal stability compared with the native protein.

  16. Structural Insight into Substrate Selection and Catalysis of Lipid Phosphate Phosphatase PgpB in the Cell Membrane.

    Science.gov (United States)

    Tong, Shuilong; Lin, Yibin; Lu, Shuo; Wang, Meitian; Bogdanov, Mikhail; Zheng, Lei

    2016-08-26

    PgpB belongs to the lipid phosphate phosphatase protein family and is one of three bacterial integral membrane phosphatases catalyzing dephosphorylation of phosphatidylglycerol phosphate (PGP) to generate phosphatidylglycerol. Although the structure of its apo form became recently available, the mechanisms of PgpB substrate binding and catalysis are still unclear. We found that PgpB was inhibited by phosphatidylethanolamine (PE) in a competitive mode in vitro Here we report the crystal structure of the lipid-bound form of PgpB. The structure shows that a PE molecule is stabilized in a membrane-embedded tunnel formed by TM3 and the "PSGH" fingerprint peptide near the catalytic site, providing structural insight into PgpB substrate binding mechanism. Noteworthy, in silico docking of varied lipid phosphates exhibited similar substrate binding modes to that of PE, and the residues in the lipid tunnel appear to be important for PgpB catalysis. The catalytic triad in the active site is essential for dephosphorylating substrates lysophosphatidic acid, phosphatidic acid, or sphingosine-1-phosphate but surprisingly not for the native substrate PGP. Remarkably, residue His-207 alone is sufficient to hydrolyze PGP, indicating a specific catalytic mechanism for PgpB in PG biosynthesis. We also identified two novel sensor residues, Lys-93 and Lys-97, on TM3. Our data show that Lys-97 is essential for the recognition of lyso-form substrates. Modification at the Lys-93 position may alter substrate specificity of lipid phosphate phosphatase proteins in prokaryotes versus eukaryotes. These studies reveal new mechanisms of lipid substrate selection and catalysis by PgpB and suggest that the enzyme rests in a PE-stabilized state in the bilayer. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. Structural Insight into Substrate Selection and Catalysis of Lipid Phosphate Phosphatase PgpB in the Cell Membrane*

    Science.gov (United States)

    Tong, Shuilong; Lin, Yibin; Lu, Shuo; Wang, Meitian; Bogdanov, Mikhail; Zheng, Lei

    2016-01-01

    PgpB belongs to the lipid phosphate phosphatase protein family and is one of three bacterial integral membrane phosphatases catalyzing dephosphorylation of phosphatidylglycerol phosphate (PGP) to generate phosphatidylglycerol. Although the structure of its apo form became recently available, the mechanisms of PgpB substrate binding and catalysis are still unclear. We found that PgpB was inhibited by phosphatidylethanolamine (PE) in a competitive mode in vitro. Here we report the crystal structure of the lipid-bound form of PgpB. The structure shows that a PE molecule is stabilized in a membrane-embedded tunnel formed by TM3 and the “PSGH” fingerprint peptide near the catalytic site, providing structural insight into PgpB substrate binding mechanism. Noteworthy, in silico docking of varied lipid phosphates exhibited similar substrate binding modes to that of PE, and the residues in the lipid tunnel appear to be important for PgpB catalysis. The catalytic triad in the active site is essential for dephosphorylating substrates lysophosphatidic acid, phosphatidic acid, or sphingosine-1-phosphate but surprisingly not for the native substrate PGP. Remarkably, residue His-207 alone is sufficient to hydrolyze PGP, indicating a specific catalytic mechanism for PgpB in PG biosynthesis. We also identified two novel sensor residues, Lys-93 and Lys-97, on TM3. Our data show that Lys-97 is essential for the recognition of lyso-form substrates. Modification at the Lys-93 position may alter substrate specificity of lipid phosphate phosphatase proteins in prokaryotes versus eukaryotes. These studies reveal new mechanisms of lipid substrate selection and catalysis by PgpB and suggest that the enzyme rests in a PE-stabilized state in the bilayer. PMID:27405756

  18. Structure of a CGI-58 Motif Provides the Molecular Basis of Lipid Droplet Anchoring*

    Science.gov (United States)

    Boeszoermenyi, Andras; Nagy, Harald Manuel; Arthanari, Haribabu; Pillip, Christoph Jens; Lindermuth, Hanna; Luna, Rafael Eulogio; Wagner, Gerhard; Zechner, Rudolf; Zangger, Klaus; Oberer, Monika

    2015-01-01

    Triacylglycerols (TGs) stored in lipid droplets (LDs) are hydrolyzed in a highly regulated metabolic process called lipolysis to free fatty acids that serve as energy substrates for β-oxidation, precursors for membrane lipids and signaling molecules. Comparative gene identification-58 (CGI-58) stimulates the enzymatic activity of adipose triglyceride lipase (ATGL), which catalyzes the hydrolysis of TGs to diacylglycerols and free fatty acids. In adipose tissue, protein-protein interactions between CGI-58 and the LD coating protein perilipin 1 restrain the ability of CGI-58 to activate ATGL under basal conditions. Phosphorylation of perilipin 1 disrupts these interactions and mobilizes CGI-58 for the activation of ATGL. We have previously demonstrated that the removal of a peptide at the N terminus (residues 10–31) of CGI-58 abrogates CGI-58 localization to LDs and CGI-58-mediated activation of ATGL. Here, we show that this tryptophan-rich N-terminal peptide serves as an independent LD anchor, with its three tryptophans serving as focal points of the left (harboring Trp21 and Trp25) and right (harboring Trp29) anchor arms. The solution state NMR structure of a peptide comprising the LD anchor bound to dodecylphosphocholine micelles as LD mimic reveals that the left arm forms a concise hydrophobic core comprising tryptophans Trp21 and Trp25 and two adjacent leucines. Trp29 serves as the core of a functionally independent anchor arm. Consequently, simultaneous tryptophan alanine permutations in both arms abolish localization and activity of CGI-58 as opposed to tryptophan substitutions that occur in only one arm. PMID:26350461

  19. Structure and thermotropic behavior of the Staphylococcus aureus lipid lysyl-dipalmitoylphosphatidylglycerol.

    Science.gov (United States)

    Danner, Sabine; Pabst, Georg; Lohner, Karl; Hickel, Andrea

    2008-03-15

    We have characterized the structural and thermotropic properties of one of the most important lipids in the cell membrane of Staphylococcus aureus, lysyl-dipalmitoylphosphatidylglycerol (lysyl-DPPG). applying differential scanning calorimetry and small- and wide-angle x-ray scattering. Microcalorimetry revealed that under physiological conditions (phosphate buffer, 20 mM NaPi, 130 mM NaCl, pH 7.4), the synthetic lysyl-DPPG resembles the features of the parent dipalmitoylphosphatidylglycerol (DPPG) with respect to its melting behavior. However, in contrast to DPPG, lowering the pH did not significantly affect the main transition temperature ( approximately 40 degrees C) of lysyl-DPPG, which can be explained by its difference in protonization because of the lysine group. X-ray experiments yielded the first information on chain packing and morphology of lysyl-DPPG. We found that lysyl-DPPG forms an interdigitated lamellar phase below the chain-melting transition. This can be explained by the large headgroup area of lysyl-DPPG as a result of its charged lysine group, especially if the headgroup is arranged parallel to the bilayer plane. Additionally, lysyl-DPPG degradation products, such as lysine and free fatty acids, had significant influences on the melting behavior and led to a multicomponent melting transition. Our results indicate that the degradation of lysyl-DPPG takes place mainly during the hydration process but also depends on lipid storage time, pH, and thermal treatment. Detailed temperature-resolved experiments at pH 5.0 demonstrated the formation of a lamellar gel phase with tilted hydrocarbon chains and a ripple phase, coexisting with the interdigitated lysyl-DPPG bilayers.

  20. Structure-activity correlation in transfection promoted by pyridinium cationic lipids.

    Science.gov (United States)

    Parvizi-Bahktar, P; Mendez-Campos, J; Raju, L; Khalique, N A; Jubeli, E; Larsen, H; Nicholson, D; Pungente, M D; Fyles, T M

    2016-03-21

    The efficiency of the transfection of a plasmid DNA encoding a galactosidase promoted by a series of pyridinium lipids in mixtures with other cationic lipids and neutral lipids was assessed in CHO-K1 cells. We identify key molecular parameters of the lipids in the mixture - clog P, lipid length, partial molar volume - to predict the morphology of the lipid-DNA lipoplex and then correlate these same parameters with transfection efficiency in an in vitro assay. We define a Transfection Index that provides a linear correlation with normalized transfection efficiency over a series of 90 different lipoplex compositions. We also explore the influence of the same set of molecular parameters on the cytotoxicity of the formulations.

  1. Structure of the antimicrobial beta-hairpin peptide protegrin-1 in a DLPC lipid bilayer investigated by molecular dynamics simulation

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Kaznessis, Yiannis N

    2007-01-01

    All atom molecular dynamics simulations of the 18-residue beta-hairpin antimicrobial peptide protegrin-1 (PG-1, RGGRLCYCRRRFCVCVGR-NH(2)) in a fully hydrated dilauroylphosphatidylcholine (DLPC) lipid bilayer have been implemented. The goal of the reported work is to investigate the structure of t...

  2. Production of specific-structured lipids by enzymatic interesterification: elucidation of acyl migration by response surface design

    DEFF Research Database (Denmark)

    Xu, Xuebing; Skands, Anja; Høy, Carl-Erik;

    1998-01-01

    Production of specific-structured lipids (SSL) by lipase-catalyzed interesterification has been attracting more and more attention recently. However, it was found that acyl migration occurs during the reaction and causes the production of by-products. In this paper, the elucidation of acyl migrat...

  3. Genetic diversity and population structure of Pisum sativum accessions for marker-trait association of lipid content

    Institute of Scientific and Technical Information of China (English)

    Sajjad Ahmad; Simerjeet Kaur; Neil Dylan Lamb-Palmer; Mark Lefsrud; Jaswinder Singh

    2015-01-01

    Field pea (Pisum sativum L.) is an important protein-rich pulse crop produced globally. Increasing the lipid content of Pisum seeds through conventional and contemporary molecular breeding tools may bring added value to the crop. However, knowledge about genetic diversity and lipid content in field pea is limited. An understanding of genetic diversity and population structure in diverse germplasm is important and a prerequisite for genetic dissection of complex characteristics and marker-trait associations. Fifty polymorphic microsatellite markers detecting a total of 207 alleles were used to obtain information on genetic diversity, population structure and marker-trait associations. Cluster analysis was performed using UPGMA to construct a dendrogram from a pairwise similarity matrix. Pea genotypes were divided into five major clusters. A model-based population structure analysis divided the pea accessions into four groups. Percentage lipid content in 35 diverse pea accessions was used to find potential associations with the SSR markers. Markers AD73, D21, and AA5 were significantly associated with lipid content using a mixed linear model (MLM) taking population structure (Q) and relative kinship (K) into account. The results of this preliminary study suggested that the population could be used for marker-trait association mapping studies.

  4. Genetic diversity and population structure of Pisum sativum accessions for marker-trait association of lipid content

    Directory of Open Access Journals (Sweden)

    Sajjad Ahmad

    2015-06-01

    Full Text Available Field pea (Pisum sativum L. is an important protein-rich pulse crop produced globally. Increasing the lipid content of Pisum seeds through conventional and contemporary molecular breeding tools may bring added value to the crop. However, knowledge about genetic diversity and lipid content in field pea is limited. An understanding of genetic diversity and population structure in diverse germplasm is important and a prerequisite for genetic dissection of complex characteristics and marker-trait associations. Fifty polymorphic microsatellite markers detecting a total of 207 alleles were used to obtain information on genetic diversity, population structure and marker-trait associations. Cluster analysis was performed using UPGMA to construct a dendrogram from a pairwise similarity matrix. Pea genotypes were divided into five major clusters. A model-based population structure analysis divided the pea accessions into four groups. Percentage lipid content in 35 diverse pea accessions was used to find potential associations with the SSR markers. Markers AD73, D21, and AA5 were significantly associated with lipid content using a mixed linear model (MLM taking population structure (Q and relative kinship (K into account. The results of this preliminary study suggested that the population could be used for marker-trait association mapping studies.

  5. Genetic diversity and population structure of Pisum sativum accessions for marker-trait association of lipid content

    Institute of Scientific and Technical Information of China (English)

    Sajjad; Ahmad; Simerjeet; Kaur; Neil; Dylan; Lamb-Palmer; Mark; Lefsrud; Jaswinder; Singh

    2015-01-01

    Field pea(Pisum sativum L.) is an important protein-rich pulse crop produced globally. Increasing the lipid content of Pisum seeds through conventional and contemporary molecular breeding tools may bring added value to the crop. However, knowledge about genetic diversity and lipid content in field pea is limited. An understanding of genetic diversity and population structure in diverse germplasm is important and a prerequisite for genetic dissection of complex characteristics and marker-trait associations. Fifty polymorphic microsatellite markers detecting a total of 207 alleles were used to obtain information on genetic diversity, population structure and marker-trait associations. Cluster analysis was performed using UPGMA to construct a dendrogram from a pairwise similarity matrix. Pea genotypes were divided into five major clusters. A model-based population structure analysis divided the pea accessions into four groups. Percentage lipid content in 35 diverse pea accessions was used to find potential associations with the SSR markers. Markers AD73, D21, and AA5 were significantly associated with lipid content using a mixed linear model(MLM) taking population structure(Q) and relative kinship(K) into account. The results of this preliminary study suggested that the population could be used for marker-trait association mapping studies.

  6. The Structure of the Polycystic Kidney Disease Channel PKD2 in Lipid Nanodiscs.

    Science.gov (United States)

    Shen, Peter S; Yang, Xiaoyong; DeCaen, Paul G; Liu, Xiaowen; Bulkley, David; Clapham, David E; Cao, Erhu

    2016-10-20

    The Polycystic Kidney Disease 2 (Pkd2) gene is mutated in autosomal dominant polycystic kidney disease (ADPKD), one of the most common human monogenic disorders. Here, we present the cryo-EM structure of PKD2 in lipid bilayers at 3.0 Å resolution, which establishes PKD2 as a homotetrameric ion channel and provides insight into potential mechanisms for its activation. The PKD2 voltage-sensor domain retains two of four gating charges commonly found in those of voltage-gated ion channels. The PKD2 ion permeation pathway is constricted at the selectivity filter and near the cytoplasmic end of S6, suggesting that two gates regulate ion conduction. The extracellular domain of PKD2, a hotspot for ADPKD pathogenic mutations, contributes to channel assembly and strategically interacts with the transmembrane core, likely serving as a physical substrate for extracellular stimuli to allosterically gate the channel. Finally, our structure establishes the molecular basis for the majority of pathogenic mutations in Pkd2-related ADPKD.

  7. Loss of lipid material during the dehulling of oilseeds with different structural characteristics.

    Science.gov (United States)

    de Figueiredo, A K; Rodríguez, L M; Fernández, M; Riccobene, I C; Nolasco, S M

    2015-12-01

    The loss of lipid material by migration to the hull during the dehulling of oilseeds with different structural characteristics was evaluated. The samples selected -three sunflower hybrids and a safflower cultivar- were processed under optimal dehulling operating conditions and with two passes through a dehuller. From the SEM micrographs of the samples it was possible to observe structural differences which affect the mechanical properties of the pericarps and, consequently, the dehulling process. The black-hull sunflower hybrid exhibited residual hull percentages lightly above those recommended by the industry after one pass through the dehuller, therefore, this hybrid should not be further processed to avoid oil losses due to migration to the hull. On the other hand, the safflower cultivar and the high stearic high oleic sunflower hybrid and the traditional striped-hull sunflower require two passes through the dehuller, but this resulted in an oil loss due to migration to the hull of over 0.9 % per gram of grains processed. These results suggest the need to reach 'compromise' decisions based on economic impact studies in the face of the variables that originate simultaneously both positive and negative effects.

  8. Possible mechanism of structural transformations induced by StAsp-PSI in lipid membranes.

    Science.gov (United States)

    Muñoz, Fernando; Palomares-Jerez, M Francisca; Daleo, Gustavo; Villalaín, José; Guevara, M Gabriela

    2014-01-01

    In the present work we have analyzed the effect of StAsp-PSI (plant-specific insert of potato aspartic protease) on the structural and thermotropic properties of the major phospholipid types of bacterial and animal cells. Results obtained suggest that StAsp-PSI induces a destabilization of the membrane bilayers, depending on the time of interaction between the protein and the bilayers, rather than on its concentration. This temporal delay would be consistent with a lateral diffusion of StAsp-PSI monomers to assemble into aggregates to form pores. Like with the results previously reported for the StAsp-PSI circular dichroism, data obtained here from IR spectroscopy show that there are slight changes in the StAsp-PSI secondary structure in the presence of lipid membranes; suggesting that these changes could be related with the StAsp-PSI self-association. Results obtained from steady-state fluorescence anisotropy and differential scanning calorimetry assays suggest that StAsp-PSI interacts with both uncharged and negatively charged phospholipids, modulates the phase polymorphic behavior of model membranes and partitions and buries differentially in the membrane depending on the presence of negatively charged phospholipids. © 2013.

  9. Lipid quantification and structure determination of nuclear envelope precursor membranes in the sea urchin.

    Science.gov (United States)

    Garnier-Lhomme, Marie; Dufourc, Erick J; Larijani, Banafshé; Poccia, Dominic

    2009-01-01

    Nuclear envelope assembly is a fundamental cellular process normally taking place once in every cell cycle in eukaryotes. The timing of fusion of nuclear membrane precursors to form the complete double membrane surrounding the chromosomes is tightly controlled, but much remains unclear concerning its regulation. Small amounts of material available and the high background of irrelevant cellular membranes have limited detailed analysis. We have employed several sensitive and high-resolution techniques to analyze the nuclear membrane structure, composition, and dynamics using purified membrane fractions and a cell-free system that results in nuclear envelope formation. We discuss the application of cholesterol and phospholipid colorimetric assays, fluorescent filipin labeling, electrospray ionization tandem mass spectrometry coupled to HPLC (HPLC-ESI/MS/MS), electron microscopy (EM), and solid-state nuclear magnetic resonance (NMR) spectroscopy. Colorimetric assays determine the amounts of inorganic phosphates from phospholipids and cholesterol/ cholesteryl esters present in membrane-containing fractions. Filipin staining of natural membranes allows the localization and relative quantification of cholesterol. HPLC-ESI/MS/MS determines the quantitative composition of membrane phospholipid species from small amounts of membranes. Cryosectioning of cryoprotected sperm cells facilitates EM verification of membrane domains existing in vivo. Deuterium solid-state NMR provides information about membrane rigidity and lipid-phase behavior. The sensitivity, quantification, and structural determinations provided by these techniques should prove useful in studying membrane dynamics in a variety of systems exhibiting membrane fusion.

  10. Structure and dynamics of Penetratin's association and translocation to a lipid bilayer

    Science.gov (United States)

    Ignacio J., General; Asciutto, Eliana K.

    2017-03-01

    Penetratin belongs to the important class of small and positively charged peptides, capable of entering cells. The determination of the optimal peptidic structure for translocation is challenging; results obtained so far are varied and dependent on several factors. In this work, we review the dynamics of association of Penetratin with a modeled dioleoyl-phosphatidylcholine (DOPC) lipid membrane using molecular dynamics simulations with last generation force fields. Penetratin's structural preferences are determined using a Markov state model. It is observed that the peptide retains a helical form in the membrane associated state, just as in water, with the exception of both termini which lose helicity, facilitating the interaction of terminal residues with the phosphate groups on the membrane's outer layer. The optimal orientation for insertion is found to be with the peptide's axis forming a small angle with the interface, and with R1 stretching toward the bilayer. The interaction between arginine side-chains and phosphate groups is found to be greater than the corresponding to lysine, mainly due to a higher number of hydrogen bonds between them. The free energy profile of translocation is qualitatively studied using Umbrella Sampling. It is found that there are different paths of penetration, that greatly differ in size of free energy barrier. The lowest path is compatible with residues R10 to K13 leading the way through the membrane and pulling the rest of the peptide. When the other side is reached, the C-terminus overtakes those residues, and finally breaks out of the membrane. The peptide's secondary structure during this traversal suffers some changes with respect to the association structure but, overall, conserves its helicity, with both termini in a more disordered state.

  11. Structure and Stability of the Spinach Aquaporin SoPIP2;1 in Detergent Micelles and Lipid Membranes

    DEFF Research Database (Denmark)

    Plasencia, Ines; Survery, Sabeen; Ibragimova, Sania;

    2011-01-01

    PC), or reconstituted into lipid membranes formed from mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS), and ergosterol. Generally, SoPIP2;1 secondary structure was found to be predominantly a...... by an increased melting temperature of up to 70 degrees C. Conclusion/Significance: The results of this study provide insights into SoPIP2;1 stability in various host membranes and suggest suitable choices of detergent and lipid composition for reconstitution of SoPIP2;1 into biomimetic membranes...

  12. Aspects of nonviral gene therapy: correlation of molecular parameters with lipoplex structure and transfection efficacy in pyridinium-based cationic lipids.

    Science.gov (United States)

    Parvizi, Paria; Jubeli, Emile; Raju, Liji; Khalique, Nada Abdul; Almeer, Ahmed; Allam, Hebatalla; Manaa, Maryem Al; Larsen, Helge; Nicholson, David; Pungente, Michael D; Fyles, Thomas M

    2014-01-30

    This study seeks correlations between the molecular structures of cationic and neutral lipids, the lipid phase behavior of the mixed-lipid lipoplexes they form with plasmid DNA, and the transfection efficacy of the lipoplexes. Synthetic cationic pyridinium lipids were co-formulated (1:1) with the cationic lipid 1,2-dimyristoyl-sn-glycero-3-ethylphosphocholine (EPC), and these lipids were co-formulated (3:2) with the neutral lipids 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) or cholesterol. All lipoplex formulations exhibited plasmid DNA binding and a level of protection from DNase I degradation. Composition-dependent transfection (beta-galactosidase and GFP) and cytotoxicity was observed in Chinese hamster ovarian-K1 cells. The most active formulations containing the pyridinium lipids were less cytotoxic but of comparable activity to a Lipofectamine 2000™ control. Molecular structure parameters and partition coefficients were calculated for all lipids using fragment additive methods. The derived shape parameter values correctly correlated with observed hexagonal lipid phase behavior of lipoplexes as derived from small-angle X-ray scattering experiments. A transfection index applicable to hexagonal phase lipoplexes derived from calculated parameters of the lipid mixture (partition coefficient, shape parameter, lipoplex packing) produced a direct correlation with transfection efficiency.

  13. Potential use of avocado oil on structured lipids MLM-type production catalysed by commercial immobilised lipases.

    Science.gov (United States)

    Caballero, Eduardo; Soto, Carmen; Olivares, Araceli; Altamirano, Claudia

    2014-01-01

    Structured Lipids are generally constituents of functional foods. Growing demands for SL are based on a fuller understanding of nutritional requirements, lipid metabolism, and improved methods to produce them. Specifically, this work was aimed to add value to avocado oil by producing dietary triacylglycerols (TAG) containing medium-chain fatty acids (M) at positions sn-1,3 and long-chain fatty acids (L) at position sn-2. These MLM-type structured lipids (SL) were produced by interesterification of caprylic acid (CA) (C8:0) and avocado oil (content of C18:1). The regiospecific sn-1,3 commercial lipases Lipozyme RM IM and TL IM were used as biocatalysts to probe the potential of avocado oil to produce SL. Reactions were performed at 30-50°C for 24 h in solvent-free media with a substrate molar ratio of 1∶2 (TAG:CA) and 4-10% w/w enzyme content. The lowest incorporation of CA (1.1% mol) resulted from Lipozyme RM IM that was incubated at 50°C. The maximum incorporation of CA into sn-1,3 positions of TAG was 29.2% mol. This result was obtained at 30°C with 10% w/w Lipozyme TL IM, which is the highest values obtained in solvent-free medium until now for structured lipids of low-calories. This strategy opens a new market to added value products based on avocado oil.

  14. Temperature-controlled structure and kinetics of ripple phases in one- and two-component supported lipid bilayers

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Leidy, Chad; Crowe, J.H.

    2003-01-01

    ripples was seen. From height profiles of the AFM images, estimates of the amplitudes of the different ripple phases are reported. To elucidate the processes of ripple formation and disappearance, a ripple-phase DPPC lipid bilayer was taken through the pretransition in the cooling and the heating...... was heated from the ripple phase and into the ripple-phase/fluid-phase coexistence temperature region, the AFM images revealed that several dynamic properties of the ripple phase are important for the melting behavior of the lipid mixture. Onset of melting is observed at grain boundaries between different......Temperature-controlled atomic force microscopy (AFM) has been used to visualize and study the structure and kinetics of ripple phases in one-component dipalmitoylphosphaticlylcholine (DPPC) and two-component dimyristoylphosphatidylcholine-distearoylphosphatidylcholine (DMPC-DSPC) lipid bilayers...

  15. Interplay of curvature-induced micro- and nanodomain structures in multicomponent lipid bilayers

    CERN Document Server

    Brodbek, Leonie

    2015-01-01

    We discuss different mechanisms for curvature-induced domain formation in multicomponent lipid membranes and present a theoretical model that allows us to study the interplay between the domains. The model represents the membrane by two coupled monolayers, which each carry an additional order parameter field describing the local lipid composition. The spontaneous curvature of each monolayer is coupled to the local composition, moreover, the lipid compositions on opposing monolayers are coupled to each other. Using this model, we calculate the phase behavior of the bilayer in mean-field approximation. The resulting phase diagrams are surprisingly complex and reveal a variety of phases and phase transitions, including a decorated microdomain phase where nanodomains are aligned along the microdomain boundaries. Our results suggest that external membrane tension can be used to control the lateral organization of nanodomains (which might be associated with lipid "rafts") in a multicomponent lipid bilayer.

  16. Effect of lipid composition on the structure and theoretical phase diagrams of DC-Chol/DOPE-DNA lipoplexes.

    Science.gov (United States)

    Muñoz-Ubeda, Mónica; Rodríguez-Pulido, Alberto; Nogales, Aurora; Martín-Molina, Alberto; Aicart, Emilio; Junquera, Elena

    2010-12-13

    Lipoplexes constituted by calf-thymus DNA (CT-DNA) and mixed cationic liposomes consisting of varying proportions of the cationic lipid 3β-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol hydrochloride (DC-Chol) and the zwitterionic lipid, 1,2-dioleoyl-sn-glycero-3-phosphoetanolamine (DOPE) have been analyzed by means of electrophoretic mobility, SAXS, and fluorescence anisotropy experiments, as well as by theoretically calculated phase diagrams. Both experimental and theoretical studies have been run at several liposome and lipoplex compositions, defined in terms of cationic lipid molar fraction, α, and either the mass or charge ratios of the lipoplex, respectively. The experimental electrochemical results indicate that DC-Chol/DOPE liposomes, with a mean hydrodynamic diameter of around (120 ± 10) nm, compact and condense DNA fragments at their cationic surfaces by means of a strong entropically driven electrostatic interaction. Furthermore, the positive charges of cationic liposomes are compensated by the negative charges of DNA phosphate groups at the isoneutrality L/D ratio, (L/D)(ϕ), which decreases with the cationic lipid content of the mixed liposome, for a given DNA concentration. This inversion of sign process has been also studied by means of the phase diagrams calculated with the theoretical model, which confirms all the experimental results. SAXS diffractograms, run at several lipoplex compositions, reveal that, irrespectively of the lipoplex charge ratio, DC-Chol/DOPE-DNA lipoplexes show a lamellar structure, L(α), when the cationic lipid content on the mixed liposomes α ≥ 0.4, while for a lower content (α = 0.2) the lipoplexes show an inverted hexagonal structure, H(II), usually related with improved cell transfection efficiency. A similar conclusion is reached from fluorescence anisotropy results, which indicate that the fluidity on liposome and lipoplexes membrane, also related with better transfection results, increases as long as the

  17. Production and structure elucidation of di- and oligosaccharide lipids (biosurfactants) from Tsukamurella sp. nov.

    Science.gov (United States)

    Vollbrecht, E; Heckmann, R; Wray, V; Nimtz, M; Lang, S

    1998-11-01

    The bacterium Tsukamurella sp. nov., isolated from soil, was found to produce novel glycolipids when grown on sunflower oil as the sole carbon source. The glycolipids were isolated by chromatography on silica columns and their structures elucidated using a combination of multidimensional NMR and MS techniques. The three main components are 2,3-di-O-acyl-alpha-D-glucopyranosyl-(1-1)-alpha-D-glucopyranose, 2,3-di-O-acyl-beta-D-glucopyranosyl-(1-2)-4,6-di-O-acyl-alpha-D- glucopyranosyl-(1-1)-alpha-D-glucopyranose and 2,3-di-O-acyl-beta-D-glucopyranosyl-(1-2)-beta-D-galactopyranosyl- (1-6)-4,6-di-O-acyl-alpha-D-glucopyranosyl-(1-1)-alpha-D- glucopyranosyl which are linked to fatty acids varying in chain length from C4 to C18. The glycolipids are mainly extracellular but are also found attached to the cell walls. During the cultivation the composition of the glycolipids changed from disaccharide- to tri- and tetrasaccharide lipids. The glycolipids show good surface-active behaviour and have antimicrobial properties.

  18. A Crystal Structure of a Dimer of the Antibiotic Ramoplanin Illustrates Membrane Positioning and a Potential Lipid II Docking Interface

    Energy Technology Data Exchange (ETDEWEB)

    Hamburger, J.; Hoertz, A; Lee, A; Senturia, R; McCafferty, D; Loll, P

    2009-01-01

    The glycodepsipeptide antibiotic ramoplanin A2 is in late stage clinical development for the treatment of infections from Gram-positive pathogens, especially those that are resistant to first line antibiotics such as vancomycin. Ramoplanin A2 achieves its antibacterial effects by interfering with production of the bacterial cell wall; it indirectly inhibits the transglycosylases responsible for peptidoglycan biosynthesis by sequestering their Lipid II substrate. Lipid II recognition and sequestration occur at the interface between the extracellular environment and the bacterial membrane. Therefore, we determined the structure of ramoplanin A2 in an amphipathic environment, using detergents as membrane mimetics, to provide the most physiologically relevant structural context for mechanistic and pharmacological studies. We report here the X-ray crystal structure of ramoplanin A2 at a resolution of 1.4 {angstrom}. This structure reveals that ramoplanin A2 forms an intimate and highly amphipathic dimer and illustrates the potential means by which it interacts with bacterial target membranes. The structure also suggests a mechanism by which ramoplanin A2 recognizes its Lipid II ligand.

  19. Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region

    Directory of Open Access Journals (Sweden)

    Paula eGuzmán

    2014-09-01

    Full Text Available The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids, coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.

  20. Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region.

    Science.gov (United States)

    Guzmán, Paula; Fernández, Victoria; Graça, José; Cabral, Vanessa; Kayali, Nour; Khayet, Mohamed; Gil, Luis

    2014-01-01

    The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids), coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.

  1. Solid lipid extrudates as sustained-release matrices: the effect of surface structure on drug release properties.

    Science.gov (United States)

    Reitz, Claudia; Strachan, Clare; Kleinebudde, Peter

    2008-11-15

    The study focused on the structural characterization of sustained-release lipid matrices prepared by solid lipid extrusion. Drug-containing lipid extrudates were locally analyzed in order to identify differences between the chemical and structural composition of surface and core elements. Independent of the lipid the dissolution from the outer extrudate surfaces was slower compared with dissolution from surfaces prepared by cutting the extrudate. The burst effect was higher for the cross-sections indicating more drug was exposed on these surfaces. The release from glycerol trimyristate (Dynasan 114) extrudates was slower compared with glycerol palmitostearate (Precirol ATO 5) extrudates. By solid-state analysis using DSC, ATR-FTIR and SEM measurements the differences between surface material and core material could be attributed mainly to morphological differences. Chemical differences between the core and the outer surface were not relevant. The differences between the surfaces might be explained by the friction induced temperature increase during extrusion in the die plate. The obtained results and a proposed scheme were used to explain the influence of different formulation/processing parameters, such as drug particle size and milling on the drug dissolution behaviour. Small drug particles and intact extrudates are a means of minimizing the burst release.

  2. Targeting of pseudorabies virus structural proteins to axons requires association of the viral Us9 protein with lipid rafts.

    Directory of Open Access Journals (Sweden)

    Mathew G Lyman

    2008-05-01

    Full Text Available The pseudorabies virus (PRV Us9 protein plays a central role in targeting viral capsids and glycoproteins to axons of dissociated sympathetic neurons. As a result, Us9 null mutants are defective in anterograde transmission of infection in vivo. However, it is unclear how Us9 promotes axonal sorting of so many viral proteins. It is known that the glycoproteins gB, gC, gD and gE are associated with lipid raft microdomains on the surface of infected swine kidney cells and monocytes, and are directed into the axon in a Us9-dependent manner. In this report, we determined that Us9 is associated with lipid rafts, and that this association is critical to Us9-mediated sorting of viral structural proteins. We used infected non-polarized and polarized PC12 cells, a rat pheochromocytoma cell line that acquires many of the characteristics of sympathetic neurons in the presence of nerve growth factor (NGF. In these cells, Us9 is highly enriched in detergent-resistant membranes (DRMs. Moreover, reducing the affinity of Us9 for lipid rafts inhibited anterograde transmission of infection from sympathetic neurons to epithelial cells in vitro. We conclude that association of Us9 with lipid rafts is key for efficient targeting of structural proteins to axons and, as a consequence, for directional spread of PRV from pre-synaptic to post-synaptic neurons and cells of the mammalian nervous system.

  3. Lipid-protein nanodiscs offer new perspectives for structural and functional studies of water-soluble membrane-active peptides.

    Science.gov (United States)

    Shenkarev, Z O; Lyukmanova, E N; Paramonov, A S; Panteleev, P V; Balandin, S V; Shulepko, M A; Mineev, K S; Ovchinnikova, T V; Kirpichnikov, M P; Arseniev, A S

    2014-04-01

    Lipid-protein nanodiscs (LPNs) are nanoscaled fragments of a lipid bilayer stabilized in solution by the apolipoprotein or a special membrane scaffold protein (MSP). In this work, the applicability of LPN-based membrane mimetics in the investigation of water-soluble membrane-active peptides was studied. It was shown that a pore-forming antimicrobial peptide arenicin-2 from marine lugworm (charge of +6) disintegrates LPNs containing both zwitterionic phosphatidylcholine (PC) and anionic phosphatidylglycerol (PG) lipids. In contrast, the spider toxin VSTx1 (charge of +3), a modifier of Kv channel gating, effectively binds to the LPNs containing anionic lipids (POPC/DOPG, 3 : 1) and does not cause their disruption. VSTx1 has a lower affinity to LPNs containing zwitterionic lipids (POPC), and it weakly interacts with the protein component of nanodiscs, MSP (charge of -6). The neurotoxin II (NTII, charge of +4) from cobra venom, an inhibitor of the nicotinic acetylcholine receptor, shows a comparatively low affinity to LPNs containing anionic lipids (POPC/DOPG, 3 : 1 or POPC/DOPS, 4 : 1), and it does not bind to LPNs/POPC. The obtained data show that NTII interacts with the LPN/POPC/DOPS surface in several orientations, and that the exchange process among complexes with different topologies proceeds fast on the NMR timescale. Only one of the possible NTII orientations allows for the previously proposed specific interaction between the toxin and the polar head group of phosphatidylserine from the receptor environment (Lesovoy et al., Biophys. J. 2009. V. 97. № 7. P. 2089-2097). These results indicate that LPNs can be used in structural and functional studies of water-soluble membrane-active peptides (probably except pore-forming ones) and in studies of the molecular mechanisms of peptide-membrane interaction.

  4. From lanosterol to cholesterol: Structural evolution and differential effects on lipid bilayers

    DEFF Research Database (Denmark)

    Miao, Ling; Nielsen, Morten; Thewalt, J.

    2002-01-01

    Cholesterol is an important molecular component of the plasma membranes of mammalian cells. Its precursor in the sterol biosynthetic pathway, lanosterol, has been argued by Konrad Bloch (Bloch, K. 1965. Science. 150:19-28; 1983. CRC Crit Rev. Biochem. 14:47-92; 1994. Blonds in Venetian Paintings......-bilayer membranes. By using deuterium NMR spectroscopy on multilamellar lipid-sterol systems in combination with Monte Carlo simulations of microscopic models of lipid-sterol interactions, we demonstrate that the evolution in the molecular chemistry from lanosterol to cholesterol is manifested in the model lipid-sterol...... membranes by an increase in the ability of the sterols to promote and stabilize a particular membrane phase, the liquid-ordered phase, and to induce collective order in the acyl-chain conformations of lipid molecules. We also discuss the biological relevance of our results, in particular in the context...

  5. Structure-guided enzymology of the lipid A acyltransferase LpxM reveals a dual activity mechanism.

    Science.gov (United States)

    Dovala, Dustin; Rath, Christopher M; Hu, Qijun; Sawyer, William S; Shia, Steven; Elling, Robert A; Knapp, Mark S; Metzger, Louis E

    2016-10-11

    Gram-negative bacteria possess a characteristic outer membrane, of which the lipid A constituent elicits a strong host immune response through the Toll-like receptor 4 complex, and acts as a component of the permeability barrier to prevent uptake of bactericidal compounds. Lipid A species comprise the bulk of the outer leaflet of the outer membrane and are produced through a multistep biosynthetic pathway conserved in most Gram-negative bacteria. The final steps in this pathway involve the secondary acylation of lipid A precursors. These are catalyzed by members of a superfamily of enzymes known as lysophospholipid acyltransferases (LPLATs), which are present in all domains of life and play important roles in diverse biological processes. To date, characterization of this clinically important class of enzymes has been limited by a lack of structural information and the availability of only low-throughput biochemical assays. In this work, we present the structure of the bacterial LPLAT protein LpxM, and we describe a high-throughput, label-free mass spectrometric assay to characterize acyltransferase enzymatic activity. Using our structure and assay, we identify an LPLAT thioesterase activity, and we provide experimental evidence to support an ordered-binding and "reset" mechanistic model for LpxM function. This work enables the interrogation of other bacterial acyltransferases' structure-mechanism relationships, and the assay described herein provides a foundation for quantitatively characterizing the enzymology of any number of clinically relevant LPLAT proteins.

  6. The Lipid Transfer Protein StarD7: Structure, Function, and Regulation

    OpenAIRE

    Susana Genti-Raimondi; Panzetta-Dutari, Graciela M.; Sofía Angeletti; Viviana Rena; Jésica Flores-Martin

    2013-01-01

    The steroidogenic acute regulatory (StAR) protein-related lipid transfer (START) domain proteins constitute a family of evolutionarily conserved and widely expressed proteins that have been implicated in lipid transport, metabolism, and signaling. The 15 well-characterized mammalian START domain-containing proteins are grouped into six subfamilies. The START domain containing 7 mRNA encodes StarD7, a member of the StarD2/phosphatidylcholine transfer protein (PCTP) subfamily, which was first i...

  7. The Lipid Transfer Protein StarD7: Structure, Function, and Regulation

    OpenAIRE

    Susana Genti-Raimondi; Panzetta-Dutari, Graciela M.; Sofía Angeletti; Viviana Rena; Jésica Flores-Martin

    2013-01-01

    The steroidogenic acute regulatory (StAR) protein-related lipid transfer (START) domain proteins constitute a family of evolutionarily conserved and widely expressed proteins that have been implicated in lipid transport, metabolism, and signaling. The 15 well-characterized mammalian START domain-containing proteins are grouped into six subfamilies. The START domain containing 7 mRNA encodes StarD7, a member of the StarD2/phosphatidylcholine transfer protein (PCTP) subfamily, which was first i...

  8. LIPID RAFTS, FLUID/FLUID PHASE SEPARATION, AND THEIR RELEVANCE TO PLASMA MEMBRANE STRUCTURE AND FUNCTION

    OpenAIRE

    Sengupta, Prabuddha; Baird, Barbara; Holowka, David

    2007-01-01

    Novel biophysical approaches combined with modeling and new biochemical data have helped to recharge the lipid raft field and have contributed to the generation of a refined model of plasma membrane organization. In this review, we summarize new information in the context of previous literature to provide new insights into the spatial organization and dynamics of lipids and proteins in the plasma membrane of live cells. Recent findings of large-scale separation of liquid-ordered and liquid-di...

  9. Polyene-lipids: a new tool to image lipids

    DEFF Research Database (Denmark)

    Kuerschner, Lars; Ejsing, Christer S.; Ekroos, Kim

    2005-01-01

    conjugated double bonds as a new type of lipid tag. Polyene-lipids exhibit a unique structural similarity to natural lipids, which results in minimal effects on the lipid properties. Analyzing membrane phase partitioning, an important biophysical and biological property of lipids, we demonstrated...... the superiority of polyene-lipids to both NBD- and BODIPY-tagged lipids. Cells readily take up various polyene-lipid precursors and generate the expected end products with no apparent disturbance by the tag. Applying two-photon excitation microscopy, we imaged the distribution of polyene-lipids in living...

  10. Properties of ceramides and their impact on the stratum corneum structure. Part 2: stratum corneum lipid model systems.

    Science.gov (United States)

    Kessner, D; Ruettinger, A; Kiselev, M A; Wartewig, S; Neubert, R H H

    2008-01-01

    The stratum corneum (SC) represents the outermost layer of the mammalian skin, exhibits the main skin barrier and plays an important role in the water penetration pathway through the SC. Knowing the structure and properties of the SC at the molecular level is essential for studying drug penetration through the SC and for the development of new dermal drug delivery systems. Therefore, research interest is focused on the SC lipid matrix and on water diffusion through it. Thus, the ultimate aim is to design a lipid mixture that mimics the barrier properties of the human SC to a high extent and that can substitute the SC in drug delivery systems. This review summarizes various studies performed on either isolated animal or human ceramide based SC model systems, coming to the result that using synthetic lipids with a well-defined architecture allows good extrapolation to the in vivo situation. This review is the continuation of part 1 that is focused on a detailed description of the thermotropic and/or lyotropic phase behaviour of single ceramide types obtained by various experimental techniques. The objective of part 2 is to reflect the numerous studies on SC lipid model systems, namely binary, ternary and multicomponent systems, during the last decade. In this context, neutron diffraction as a prospective tool for analyzing the internal membrane structure is addressed in particular. Based on these new insights, current SC models are presented, whose validations are still under discussion. A profound knowledge about SC lipid organization at the molecular level is still missing.

  11. Rapid fabrication of three-dimensional structures for dielectrophoretic sorting of lipid-containing organisms

    Science.gov (United States)

    Schor, Alisha R.; Buie, Cullen R.

    2016-10-01

    In this work, we demonstrate a microfluidic particle sorter consisting of three-dimensional, conducting microposts. Our sorter uses dielectrophoresis (DEP) to sort high- and low-lipid phenotypes of the yeast Yarrowia lipolytica. Y. lipolytica is one of the many microorganisms being explored as a hydrocarbon source for biodiesel, Omega-3 additives, and other products derived from fatty acids. A rapid, non-destructive, lipid-based sorting tool would accelerate the commercialization of these products. Our device consists of an array of 105, 25 μm wide gold microposts that span the height of a 15 μm channel. This array generates an electric field in a microfluidic device that is uniform through the channel height, but has a custom-shaped non-uniformity in the horizontal directions. This is crucial in order to achieve continuous sorting using DEP, as it ensures all cells are exposed to the same conditions throughout the channel height. By using very low currents (100 μA), we are able to electroplate these post arrays in fewer than 15 min. This is an order of magnitude improvement over previous reports of electroplated microstructures. With an applied signal of 250 MHz, 2.6 V pp in our device, we separate a heterogeneous population with a purity of 97.8% in the low-lipid stream and 71.4% in the high-lipid stream. The high-lipid stream purity can be improved by adjusting the spacing of the array. This unique protocol for the rapid fabrication of 3D microstructures has enabled the creation of a non-invasive sorting tool for genetically engineered, lipid-producing organisms. The ability to screen organisms based on lipid content will alleviate one of the major bottlenecks in commercialization of microbial biofuels.

  12. Effects of Low Concentrations of Docosahexaenoic Acid on the Structure and Phase Behavior of Model Lipid Membranes

    Directory of Open Access Journals (Sweden)

    Chai Lor

    2015-12-01

    Full Text Available In this paper we report an X-ray diffraction study on the phase behavior of binary lipid mixtures of 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (DHA-PE and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC at low concentrations below 5.0 mol% DHA-PE. Our results show that DHA-PE induces phase separation into a DHA rich liquid crystalline (Lα phase and a DHA poor gel (Lβ′ phase at overall DHA-PE concentrations as low as 0.1 mol%. In addition, we find that the structure of the Lβ′ phase, from which the DHA-PE molecules are largely excluded, is modified in the phase-separated state at low DHA-PE concentrations, with a decrease in bilayer thickness of 1.34 nm for 0.1 mol% at room temperature, compared to pure DPPC bilayers. This result is contrary to that seen in similar studies on mono-unsaturated lipids where an increase in bilayer thickness is observed. The surprising effect of such low DHA-PE concentrations on membrane structure may be important in understanding the role of highly polyunsaturated lipids in biological membrane-based structures and similar artificial surfactant systems.

  13. Structural analysis of Herbaspirillum seropedicae lipid-A and of two mutants defective to colonize maize roots.

    Science.gov (United States)

    Serrato, Rodrigo V; Balsanelli, Eduardo; Sassaki, Guilherme L; Carlson, Russell W; Muszynski, Artur; Monteiro, Rose A; Pedrosa, Fábio O; Souza, Emanuel M; Iacomini, Marcello

    2012-11-01

    Lipid-A was isolated by mild acid hydrolysis from lipopolysaccharides extracted from cells of Herbaspirillum seropedicae, strain SMR1, and from two mutants deficient in the biosynthesis of rhamnose (rmlB⁻ and rmlC⁻). Structural analyzes were carried out using MALDI-TOF and derivatization by per-O-trimethylsilylation followed by GC-MS in order to determine monosaccharide and fatty acid composition. De-O-acylation was also performed to determine the presence of N-linked fatty acids. Lipid-A from H. seropedicae SMR1 showed a major structure comprising 2-amino-2-deoxy-glucopyranose-(1→6)-2-amino-2-deoxy-glucopyranose phosphorylated at C4' and C1 positions, each carrying a unit of 4-amino-4-deoxy-arabinose. C2 and C2' positions were substituted by amide-linked 3-hydroxy-dodecanoic acids. Both rhamnose-defective mutants showed similar structure for their lipid-A moieties, except for the lack of 4-amino-4-deoxy-arabinose units attached to phosphoryl groups.

  14. Potential use of avocado oil on structured lipids MLM-type production catalysed by commercial immobilised lipases.

    Directory of Open Access Journals (Sweden)

    Eduardo Caballero

    Full Text Available Structured Lipids are generally constituents of functional foods. Growing demands for SL are based on a fuller understanding of nutritional requirements, lipid metabolism, and improved methods to produce them. Specifically, this work was aimed to add value to avocado oil by producing dietary triacylglycerols (TAG containing medium-chain fatty acids (M at positions sn-1,3 and long-chain fatty acids (L at position sn-2. These MLM-type structured lipids (SL were produced by interesterification of caprylic acid (CA (C8:0 and avocado oil (content of C18:1. The regiospecific sn-1,3 commercial lipases Lipozyme RM IM and TL IM were used as biocatalysts to probe the potential of avocado oil to produce SL. Reactions were performed at 30-50°C for 24 h in solvent-free media with a substrate molar ratio of 1∶2 (TAG:CA and 4-10% w/w enzyme content. The lowest incorporation of CA (1.1% mol resulted from Lipozyme RM IM that was incubated at 50°C. The maximum incorporation of CA into sn-1,3 positions of TAG was 29.2% mol. This result was obtained at 30°C with 10% w/w Lipozyme TL IM, which is the highest values obtained in solvent-free medium until now for structured lipids of low-calories. This strategy opens a new market to added value products based on avocado oil.

  15. Polyhydroxy surfactants for the formulation of lipid nanoparticles (SLN and NLC): effects on size, physical stability and particle matrix structure.

    Science.gov (United States)

    Kovacevic, A; Savic, S; Vuleta, G; Müller, R H; Keck, C M

    2011-03-15

    The two polyhydroxy surfactants polyglycerol 6-distearate (Plurol(®)Stearique WL1009 - (PS)) and caprylyl/capryl glucoside (Plantacare(®) 810 - (PL)) are a class of PEG-free stabilizers, made from renewable resources. They were investigated for stabilization of aqueous solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) dispersions. Production was performed by high pressure homogenization, analysis by photon correlation spectroscopy (PCS), laser diffraction (LD), zeta potential measurements and differential scanning calorimetry (DSC). Particles were made from Cutina CP as solid lipid only (SLN) and its blends with Miglyol 812 (NLC, the blends containing increasing amounts of oil from 20% to 60%). The obtained particle sizes were identical for both surfactants, about 200 nm with polydispersity indices below 0.20 (PCS), and unimodal size distribution (LD). All dispersions with both surfactants were physically stable for 3 months at room temperature, but Plantacare (PL) showing a superior stability. The melting behaviour and crystallinity of bulk lipids/lipid blends were compared to the nanoparticles. Both were lower for the nanoparticles. The crystallinity of dispersions stabilized with PS was higher, the zeta potential decreased with storage time associated with this higher crystallinity, and leading to a few, but negligible larger particles. The lower crystallinity particles stabilized with PL remained unchanged in zeta potential (about -50 mV) and in size. These data show that surfactants have a distinct influence on the particle matrix structure (and related stability and drug loading), to which too little attention was given by now. Despite being from the same surfactant class, the differences on the structure are pronounced. They are attributed to the hydrophobic-lipophilic tail structure with one-point anchoring in the interface (PL), and the loop conformation of PS with two hydrophobic anchor points, i.e. their molecular structure and its

  16. Supramolecular Langmuir monolayers and multilayered vesicles of self-assembling DNA–lipid surface structures and their further implications in polyelectrolyte-based cell transfections

    Energy Technology Data Exchange (ETDEWEB)

    Demirsoy, Fatma Funda Kaya [Ankara University, The Central Laboratory of The Institute of Biotechnology (Turkey); Eruygur, Nuraniye [Gazi University, Department of Pharmacognosy, Faculty of Pharmacy (Turkey); Süleymanoğlu, Erhan, E-mail: erhans@mail.ru [Gazi University, Department of Pharmaceutical Chemistry, Faculty of Pharmacy (Turkey)

    2015-01-15

    The basic interfacial characteristics of DNA–lipid recognitions have been studied. The complex structures of individual unbound DNA molecules and their binary and ternary complexes with zwitterionic lipids and divalent cations were followed by employing lipid monolayers at the air–liquid interfaces, as well as by performing various microscopic, spectroscopic, and thermodynamic measurements with multilayered vesicles. The pressure-area isotherms depicted that Mg{sup 2+}-ions increase the surface pressure of lipid films and thus give rise to electrostatic and hydrophobic lipid–DNA interactions in terms of DNA adsorption, adhesion, and compaction. These features were further approached by using multilamellar vesicles with a mean diameter of 850 nm, where a metal ion-directed nucleic acid compaction and condensation effects were shown. The data obtained show the effectiveness of Langmuir monolayers and lipid multilayers in studying nucleic acid–lipid recognitions. The data provide with further details and support previous reports on mainly structural features of these recognitions. Biomolecular surface recognition events were presented in direct link with spectral and thermodynamic features of lipid vesicle–polynucleotide complex formations. The results serve to build a theoretical model considering the use of neutral lipids in lipoplex designs as a polyelectrolyte alternatives to the currently employed cytotoxic cationic liposomes. The supramolecular structures formed and their possible roles in interfacial electrostatic and hydrophobic mechanisms of endosomal escape in relevant cell transfection assays are particularly emphasized.

  17. Effect of emulsifiers and physical structure on lipid oxidation in omega-3 emulsions

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Jacobsen, Charlotte

    The body of evidence supporting health beneficial effects of long-chain omega-3 polyunsaturated fatty acids has increased over the last decades. Consequently, the interest in fish oil-enriched foods has also increased. However, addition of these highly unsaturated fatty acids to foods also adds...... the challenge of lipid oxidation. In order to limit lipid oxidation and the consecutive development of unpleasant off-flavours, the manner in which the fish oil is introduced to the food product should be carefully considered, e.g. an emulsion could be used as delivery system for the omega-3s. The aim...

  18. Unordered structured of proinsulin C-peptide in aqueous solution and in the presence of lipid vesicles.

    Science.gov (United States)

    Henriksson, M; Shafqat, J; Liepinsh, E; Tally, M; Wahren, J; Jörnvall, H; Johansson, J

    2000-02-01

    Proinsulin C-peptide ameliorates renal and autonomic nerve function and increases skeletal muscle blood flow, oxygen uptake and glucose transport in patients with insulin-dependent diabetes mellitus. These effects have in part been ascribed to the stimulatory influence of C-peptide on Na+,K+-ATPase and endothelial nitric oxide synthase. To evaluate the capacity of C-peptide to insert into lipid bilayers and form ion channels, C-peptide secondary structure and membrane interactions were studied with circular dichroism spectroscopy and size exclusion chromatography. C-peptide is shown to lack a stable secondary structure, both when part of proinsulin and when free in aqueous solution, although the N-terminal third of the peptide exhibits an alpha-helical conformation in trifluoroethanol. Moreover, C-peptide remains disordered in the aqueous solvent in the presence of lipid vesicles, regardless of vesicle composition. In conclusion, C-peptide is unlikely to elicit physiological effects through stable conformation-dependent interactions with lipid membranes.

  19. NMR structural studies of the bacterial outer membrane protein OmpX in oriented lipid bilayer membranes.

    Science.gov (United States)

    Mahalakshmi, Radhakrishnan; Franzin, Carla M; Choi, Jungyuen; Marassi, Francesca M

    2007-12-01

    The beta-barrels found in the outer membranes of prokaryotic and eukaryotic organisms constitute an important functional class of proteins. Here we present solid-state NMR spectra of the bacterial outer membrane protein OmpX in oriented lipid bilayer membranes. We show that OmpX is folded in both glass-supported oriented lipid bilayers and in lipid bicelles that can be magnetically oriented with the membrane plane parallel or perpendicular to the direction of the magnetic field. The presence of resolved peaks in these spectra demonstrates that OmpX undergoes rotational diffusion around an axis perpendicular to the membrane surface. A tightly hydrogen-bonded domain of OmpX resists exchange with D2O for days and is assigned to the transmembrane beta-barrel, while peaks at isotropic resonance frequencies that disappear rapidly in D2O are assigned to the extracellular and periplasmic loops. The two-dimensional 1H/15N separated local field spectra of OmpX have several resolved peaks, and agree well with the spectra calculated from the crystal structure of OmpX rotated with the barrel axis nearly parallel (5 degrees tilt) to the direction of the magnetic field. The data indicate that it will be possible to obtain site-specific resonance assignments and to determine the structure, tilt, and rotation of OmpX in membranes using the solid-state NMR methods that are currently being applied to alpha-helical membrane proteins.

  20. Structural and functional characterization of human apolipoprotein E 72-166 peptides in both aqueous and lipid environments

    Directory of Open Access Journals (Sweden)

    Chou Chi-Yuan

    2011-01-01

    Full Text Available Abstract Backgrounds There are three apolipoprotein E (apoE isoforms involved in human lipid homeostasis. In the present study, truncated apoE2-, apoE3- and apoE4-(72-166 peptides that are tailored to lack domain interactions are expressed and elucidated the structural and functional consequences. Methods & Results Circular dichroism analyses indicated that their secondary structure is still well organized. Analytical ultracentrifugation analyses demonstrated that apoE-(72-166 produces more complicated species in PBS. All three isoforms were significantly dissociated in the presence of dihexanoylphosphatidylcholine. Dimyristoylphosphatidylcholine turbidity clearance assay showed that apoE4-(72-166 maintains the highest lipid-binding capacity. Finally, only apoE4-(72-166 still maintained significant LDL receptor binding ability. Conclusions Overall, apoE4-(72-166 peptides displayed a higher lipid-binding and comparable receptor-binding ability as to full-length apoE. These findings provide the explanation of diverged functionality of truncated apoE isoforms.

  1. Lipid membrane partitioning of lysolipids and fatty acids: Effects of membrane phase structure and detergent chain length

    DEFF Research Database (Denmark)

    Høyrup, Lise Pernille Kristine; Davidsen, Jesper; Jørgensen, Kent

    2001-01-01

    The lipid membrane partitioning of lysolipids (lysoPC) and fatty acids (FA) into unilamellar vesicles composed of saturated DC$-16$/PC phospholipids has been determined by means of isothermal titration calorimetry (ITC). The calorimetric titrations were performed at low temperatures in the ordered...... gel phase and at high temperatures in the disordered fluid phase of the phospholipid membrane vesicles. The long saturated acyl chains of the lysolipids and fatty acids varied from 10 to 16 carbon atoms and all titrations were performed below the critical micellar concentrations (cmc....... Oppositely, the membrane partitioning of fatty acids depends only weakly on the phase structure of the phospholipid vesicles. In addition, the thermodynamic measurements show that the partition coefficients for both the lysolipids and fatty acids toward gel and fluid lipid membranes become almost an order...

  2. Effect of dietary lipid structure in early postnatal life on mouse adipose tissue development and function in adulthood.

    Science.gov (United States)

    Oosting, Annemarie; van Vlies, Naomi; Kegler, Diane; Schipper, Lidewij; Abrahamse-Berkeveld, Marieke; Ringler, Silvia; Verkade, Henkjan J; van der Beek, Eline M

    2014-01-28

    Obese individuals have more (hyperplastic) and larger (hypertrophic) adipocytes in their white adipose tissue (WAT) than normal-weight individuals. The difference in cell number emerges early in childhood, suggesting that this is a critical period for being susceptible to obesity. Breast-feeding has been shown to be protective against obesity, and we have previously shown in mice that the physical structure of lipids in human milk may contribute to this protective effect. In the present study, we investigated how differences in the physical structure of lipids in the early diet may modulate adipose tissue development. Male mice were fed a diet containing control infant milk formula (Control IMF; Danone Research) or Nuturis® (Concept IMF with large phospholipid-coated lipid droplets; Danone Research) from postnatal day (PN)16 to 42. Subsequently, mice were challenged with a moderate Western-style diet (WSD) until PN98, and body composition was monitored by dual-energy X-ray absorptiometry. Epididymal WAT was analysed for adipocyte size, number and gene expression of metabolic transcription factors. Early Concept IMF exposure reduced fat accumulation during the WSD challenge by 30 % compared with the Control IMF. It reduced adipocyte size without affecting adipocyte number in adult mice. The Concept IMF decreased the expression of PPARγ, CCAAT/enhancer-binding protein and retinoid X receptor α in WAT in adulthood, key regulators of metabolic activity. In conclusion, Concept IMF exposure in early life reduced susceptibility to obesity in adult life, by preventing adipocyte hypertrophia upon adult dietary challenge without affecting adipogenesis. These data emphasise the importance of the physical properties of dietary lipids in early life in obesity risk later in life.

  3. Intact polar lipids of ammonia-oxidizing Archaea: structural diversity application in molecular ecology

    NARCIS (Netherlands)

    Pitcher, A.M.

    2011-01-01

    Non-extremophilic Crenarchaeota are ubiquitous, and comprise a major component of the microbial assemblages in many modern-day systems. Several studies have analyzed glycerol dialkyl glycerol tetraether (GDGT) membrane lipids synthesized by non-extremophilic Crenarchaeota to interpret the presence,

  4. Intact polar lipids of ammonia-oxidizing Archaea: Structural diversity anapplication inmolecular ecology

    NARCIS (Netherlands)

    Pitcher, A.

    2011-01-01

    Non-extremophilic Crenarchaeota are ubiquitous, and comprise a major component of the microbial assemblages in many modern-day systems. Several studies have analyzed glycerol dialkyl glycerol tetraether (GDGT) membrane lipids synthesized by Crenarchaeota to interpret the presence, distribution, and

  5. Intact polar lipids of ammonia-oxidizing Archaea: Structural diversity anapplication inmolecular ecology

    NARCIS (Netherlands)

    Pitcher, A.

    2011-01-01

    Non-extremophilic Crenarchaeota are ubiquitous, and comprise a major component of the microbial assemblages in many modern-day systems. Several studies have analyzed glycerol dialkyl glycerol tetraether (GDGT) membrane lipids synthesized by Crenarchaeota to interpret the presence, distribution, and

  6. Intact polar lipids of ammonia-oxidizing Archaea: structural diversity application in molecular ecology

    NARCIS (Netherlands)

    Pitcher, A.M.

    2011-01-01

    Non-extremophilic Crenarchaeota are ubiquitous, and comprise a major component of the microbial assemblages in many modern-day systems. Several studies have analyzed glycerol dialkyl glycerol tetraether (GDGT) membrane lipids synthesized by non-extremophilic Crenarchaeota to interpret the presence,

  7. Fluorescence study of domain structure and lipid interaction of human apolipoproteins E3 and E4.

    Science.gov (United States)

    Mizuguchi, Chiharu; Hata, Mami; Dhanasekaran, Padmaja; Nickel, Margaret; Okuhira, Keiichiro; Phillips, Michael C; Lund-Katz, Sissel; Saito, Hiroyuki

    2014-12-01

    Human apolipoprotein E (apoE) isoforms exhibit different conformational stabilities and lipid-binding properties that give rise to altered cholesterol metabolism among the isoforms. Using Trp-substituted mutations and site- directed fluorescence labeling, we made a comprehensive comparison of the conformational organization of the N- and C-terminal domains and lipid interactions between the apoE3 and apoE4 isoforms. Trp fluorescence measurements for selectively Trp-substituted variants of apoE isoforms demonstrated that apoE4 adopts less stable conformations in both the N- and C-terminal domains compared to apoE3. Consistent with this, the conformational reorganization of the N-terminal helix bundle occurs at lower guanidine hydrochloride concentration in apoE4 than in apoE3 as monitored by fluorescence resonance energy transfer (FRET) from Trp residues to acrylodan attached at the N-terminal helix. Upon binding of apoE3 and apoE4 variants to egg phosphatidylcholine small unilamellar vesicles, similar changes in Trp fluorescence or FRET efficiency were observed for the isoforms, indi- cating that the opening of the N-terminal helix bundle occurs similarly in apoE3 and apoE4. Introduction of mutations into the C-terminal domain of the apoE isoforms to prevent self-association and maintain the monomeric state resulted in great increase in the rate of binding of the C-terminal helices to a lipid surface. Overall, our results demonstrate that the different conformational organizations of the N- and C-terminal domains have a minor effect on the steady-state lipid-binding behavior of apoE3 and apoE4: rather, self-association property is a critical determinant in the kinetics of lipid binding through the C-terminal helices of apoE isoforms.

  8. Melting properties of some structured lipids native to high stearic acid soybean oil

    Directory of Open Access Journals (Sweden)

    Dunn, R. O.

    2004-06-01

    Full Text Available A number of structured lipids native to high stearic acid soybean oil were synthesized and their physical properties were determined by pulsed nuclear magnetic resonance (NMR, Mettler dropping point and differential scanning calorimetry (DSC. 1,3 Distearo-2-olein (SOS, 1,3 distearo-2-linolein (SLS and1,3 distearo-2-linolenin (SlnS were synthesized from pure 1,3 diacylglycerols and the appropriate fatty acid. Pulsed NMR determinations over the temperature range 10-50 ºC showed that the symmetrical triacylglycerols (SUS: where S = stearic, U = oleic, linoleic or linolenic are high and sharply melting materials, all showing substantial amounts of solids at temperatures up to 33.3 ºC, yet are completely melted at only a few degrees higher. Mettler dropping points for SOS, SLS and SlnS were 44.1, 37.9 and 36.5 ºC respectively. The heats of fusion for the structured triacylglycerols were determined by DSC and shown to be of the order 29-32 cal/gm compared to 45 cal/gm for SSS. The heats of fusion were also calculated from Mettler dropping point determinations as admixtures with soybean oil and showed consistent agreement with the DSC data.Se sintetizaron algunos lípidos estructurados procedentes del aceite de soja con alto contenido en ácido esteárico y sus propiedades físicas se determinaron por resonancia magnética nuclear pulsada (NMR, punto de goteo Mettler y calorimetría diferencial de barrido (DSC. Se sintetizaron 1,3 diestearo-2-oleina (SOS, 1,3 diestearo-2-linoleina (SLS y 1,3 diestearo-2-linolenina (SlnS a partir de 1,3 diacilgliceroles y de los ácidos grasos adecuados puros. Las determinaciones de NMR pulsada en el rango de temperaturas 10- 50 ºC mostraron que los triacilgliceroles simétricos (SUS: donde S = esteárico, U = oleico, linoleico o linolénico funden a mayor temperatura y más bruscamente, todos presentan altos contenidos en sólidos a todas las temperaturas hasta los 33.3 ºC, estando completamente fundidos

  9. Impact of Actinobacillus pleuropneumoniae biofilm mode of growth on the lipid A structures and stimulation of immune cells.

    Science.gov (United States)

    Hathroubi, Skander; Beaudry, Francis; Provost, Chantale; Martelet, Léa; Segura, Mariela; Gagnon, Carl A; Jacques, Mario

    2016-07-01

    Actinobacillus pleuropneumoniae (APP), the etiologic agent of porcine pleuropneumonia, forms biofilms on biotic and abiotic surfaces. APP biofilms confers resistance to antibiotics. To our knowledge, no studies have examined the role of APP biofilm in immune evasion and infection persistence. This study was undertaken to (i) investigate biofilm-associated LPS modifications occurring during the switch to biofilm mode of growth; and (ii) characterize pro-inflammatory cytokines expression in porcine pulmonary alveolar macrophages (PAMs) and proliferation in porcine PBMCs challenged with planktonic or biofilm APP cells. Extracted lipid A samples from biofilm and planktonic cultures were analyzed by HPLC high-resolution, accurate mass spectrometry. Biofilm cells displayed significant changes in lipid A profiles when compared with their planktonic counterparts. Furthermore, in vitro experiments were conducted to examine the inflammatory response of PAMs exposed to UV-inactivated APP grown in biofilm or in suspension. Relative mRNA expression of pro-inflammatory genes IL1, IL6, IL8 and MCP1 decreased in PAMs when exposed to biofilm cells compared to planktonic cells. Additionally, the biofilm state reduced PBMCs proliferation. Taken together, APP biofilm cells show a weaker ability to stimulate innate immune cells, which could be due, in part, to lipid A structure modifications. © The Author(s) 2016.

  10. High Resolution Structure of the ba3 Cytochrome c Oxidase from Thermus thermophilus in a Lipidic Environment

    Energy Technology Data Exchange (ETDEWEB)

    Tiefenbrunn, Theresa; Liu, Wei; Chen, Ying; Katritch, Vsevolod; Stout, C. David; Fee, James A.; Cherezov, Vadim (Scripps); (UCSD)

    2012-06-27

    The fundamental chemistry underpinning aerobic life on Earth involves reduction of dioxygen to water with concomitant proton translocation. This process is catalyzed by members of the heme-copper oxidase (HCO) superfamily. Despite the availability of crystal structures for all types of HCO, the mode of action for this enzyme is not understood at the atomic level, namely how vectorial H{sup +} and e{sup -} transport are coupled. Toward addressing this problem, we report wild type and A120F mutant structures of the ba{sub 3}-type cytochrome c oxidase from Thermus thermophilus at 1.8 {angstrom} resolution. The enzyme has been crystallized from the lipidic cubic phase, which mimics the biological membrane environment. The structures reveal 20 ordered lipid molecules that occupy binding sites on the protein surface or mediate crystal packing interfaces. The interior of the protein encloses 53 water molecules, including 3 trapped in the designated K-path of proton transfer and 8 in a cluster seen also in A-type enzymes that likely functions in egress of product water and proton translocation. The hydrophobic O{sub 2}-uptake channel, connecting the active site to the lipid bilayer, contains a single water molecule nearest the Cu{sub B} atom but otherwise exhibits no residual electron density. The active site contains strong electron density for a pair of bonded atoms bridging the heme Fe{sub a3} and Cu{sub B} atoms that is best modeled as peroxide. The structure of ba{sub 3}-oxidase reveals new information about the positioning of the enzyme within the membrane and the nature of its interactions with lipid molecules. The atomic resolution details provide insight into the mechanisms of electron transfer, oxygen diffusion into the active site, reduction of oxygen to water, and pumping of protons across the membrane. The development of a robust system for production of ba{sub 3}-oxidase crystals diffracting to high resolution, together with an established expression system

  11. High resolution structure of the ba3 cytochrome c oxidase from Thermus thermophilus in a lipidic environment.

    Directory of Open Access Journals (Sweden)

    Theresa Tiefenbrunn

    Full Text Available The fundamental chemistry underpinning aerobic life on Earth involves reduction of dioxygen to water with concomitant proton translocation. This process is catalyzed by members of the heme-copper oxidase (HCO superfamily. Despite the availability of crystal structures for all types of HCO, the mode of action for this enzyme is not understood at the atomic level, namely how vectorial H(+ and e(- transport are coupled. Toward addressing this problem, we report wild type and A120F mutant structures of the ba(3-type cytochrome c oxidase from Thermus thermophilus at 1.8 Å resolution. The enzyme has been crystallized from the lipidic cubic phase, which mimics the biological membrane environment. The structures reveal 20 ordered lipid molecules that occupy binding sites on the protein surface or mediate crystal packing interfaces. The interior of the protein encloses 53 water molecules, including 3 trapped in the designated K-path of proton transfer and 8 in a cluster seen also in A-type enzymes that likely functions in egress of product water and proton translocation. The hydrophobic O(2-uptake channel, connecting the active site to the lipid bilayer, contains a single water molecule nearest the Cu(B atom but otherwise exhibits no residual electron density. The active site contains strong electron density for a pair of bonded atoms bridging the heme Fe(a3 and Cu(B atoms that is best modeled as peroxide. The structure of ba(3-oxidase reveals new information about the positioning of the enzyme within the membrane and the nature of its interactions with lipid molecules. The atomic resolution details provide insight into the mechanisms of electron transfer, oxygen diffusion into the active site, reduction of oxygen to water, and pumping of protons across the membrane. The development of a robust system for production of ba(3-oxidase crystals diffracting to high resolution, together with an established expression system for generating mutants, opens the

  12. The membrane-induced structure of melittin is correlated with the fluidity of the lipids.

    Science.gov (United States)

    Andersson, August; Biverståhl, Henrik; Nordin, Jon; Danielsson, Jens; Lindahl, Emma; Mäler, Lena

    2007-01-01

    The effect of the bee toxin melittin on DMPC dynamics in fast-tumbling bicelles has been investigated. The (13)C R(1) and (13)C-(1)H NOE relaxation parameters for DMPC were used to monitor the effect of melittin and cholesterol on lipid dynamics. It was found that melittin has the largest effect on the DMPC mobility in DMPC/DHPC bicelles, while less effect was observed in cholesterol-doped bicelles, or in bicelles made with CHAPS, indicating that the rigidity of the membrane affects the melittin-membrane interaction. CD spectra were analysed in terms of cooperativity of the alpha-helix to random coil transition in melittin, and these results also indicated similar differences between the bicelles. The study shows that bicelles can be used to investigate lipid dynamics by spin relaxation, and in particular of peptide-induced changes in membrane fluidity.

  13. The Molecular Structure of the Liquid Ordered Phase of Lipid Bilayers

    Science.gov (United States)

    Sodt, Alexander J.; Sandar, Michael Logan; Gawrisch, Klaus; Pastor, Richard W.; Lyman, Edward

    2014-01-01

    Molecular dynamics simulations reveal substructures within the liquid-ordered phase of lipid bilayers. These substructures, identified in a 10 μsec all-atom trajectory of liquid-ordered/liquid-disordered coexistence (Lo/Ld), are composed of saturated hydrocarbon chains packed with local hexagonal order, and separated by interstitial regions enriched in cholesterol and unsaturated chains. Lipid hydrocarbon chain order parameters calculated from the Lo phase are in excellent agreement with 2H NMR measurements; the local hexagonal packing is also consistent with 1H-MAS NMR spectra of the Lo phase, NMR diffusion experiments, and small angle X-ray- and neutron scattering. The balance of cholesterol-rich to local hexagonal order is proposed to control the partitioning of membrane components into the Lo regions. The latter have been frequently associated with formation of so-called rafts, platforms in the plasma membranes of cells that facilitate interaction between components of signaling pathways. PMID:24345334

  14. Modulation of lipid digestibility using structured emulsion-based delivery systems: comparison of in vivo and in vitro measurements.

    Science.gov (United States)

    Li, Yan; Kim, Jonggun; Park, Yeonhwa; McClements, David Julian

    2012-05-01

    Emulsion-based delivery systems are finding increasing application to enhance the oral bioavailability of poorly water-soluble pharmaceuticals and nutraceuticals, and to control the biological fate of ingested lipids. These systems can be designed to encapsulate lipophilic components, and then release them at specific locations within the gastrointestinal tract. The current study evaluated the performance of four emulsion-based delivery systems with different structures: (A) conventional emulsions; (B) small microcluster emulsions; (C) large microcluster emulsions; (D) filled hydrogel beads. These systems were fabricated from protein-coated lipid droplets, alginate, and/or calcium. The mean diameters (d₄₃) of the particles in these systems were 0.36, 4.7, 200, and 510 μm, respectively. The fate of the delivery systems within the gastrointestinal tract was ascertained by introducing them into rat stomachs. Confocal microscopy showed that system D remained intact in the stomach, but systems A, B and C exhibited considerable disruption leading to droplet coalescence. No intact delivery systems were observed within the small intestine using optical microscopy. Gas chromatography analysis using a marker lipid (tridecanoic acid) demonstrated that absorption was increasingly inhibited as the size of the droplet-biopolymer complexes increased, i.e., A > B > C > D. These results are in good qualitative agreement with previous in vitro digestion studies using similar delivery systems. This study showed that an in vitro digestion model is a useful predictive tool for in vivo feeding studies, and that encapsulation is an effective strategy to control the fate of lipids within the gastrointestinal (GI) tract.

  15. Production of structured lipids: acyl migration during enzymatic interesterification and downstream processing

    DEFF Research Database (Denmark)

    Xu, Xuebing

    1997-01-01

    -2 position or sn-1,3 positions of glycerol backbone. These kinds of lipids are reported to be promising for both enteral and parenteral nutrition. However, acyl migration occurs in the reaction stage and downstream purification process. This side-reaction causes by-products which are harmful...... to the required products. In this paper, the reasons of acyl migration and factors affecting the acyl migration were reviewed and discussed. The possible solutions were also evaluated....

  16. Vitamin C conjugates of genotoxic lipid peroxidation products: Structural characterization and detection in human plasma

    OpenAIRE

    Sowell, John; Frei, Balz; Stevens, Jan F.

    2004-01-01

    α,β-Unsaturated aldehydes such as 4-hydroxy-2-nonenal (HNE) and other electrophilic lipid peroxidation (LPO) products may contribute to the pathogenesis of cancer, cardiovascular diseases, and other age-related diseases by cytotoxic, genotoxic, and proinflammatory mechanisms. The notion that vitamin C (ascorbic acid) acts as a biological antioxidant has been challenged recently by an in vitro study showing that ascorbic acid promotes, rather than inhibits, the formation of genotoxic LPO produ...

  17. Lactosomes: structural and compositional classification of unique nanometer-sized protein lipid particles of human milk

    OpenAIRE

    2010-01-01

    Milk fat globules (MFG) are accepted primarily as triacylglycerol delivery systems. The identification of nanometer-sized lipid-protein particles termed ‘lactosomes’ that do not contain triacylglycerol raises the question of their possible functions. MFGs were isolated by slow centrifugation and lactosomes were isolated by ultracentrifugation at a density equivalent to plasma HDL (d > 1.063 g/ml) from human milk obtained from six volunteers at different lactation stages. Isolated lactosomes w...

  18. [HYGIENIC ASSESSMENT OF THE LIPID COMPONENT IN THE STRUCTURE OF NUTRITION OF STUDENT YOUNG ADULTS].

    Science.gov (United States)

    Vilms, E A; Turchaninova, M S; Shupina, M I; Gogol, D M; Turchaninov, D V

    2015-01-01

    The actual nutrition of the Omsk University students aged 18-27 years, was studied with the use of the method of the analysis of the frequency of food consumption. There is done quantitative assessment of nutrient consumption related to the fat component of food. There is described the qualitative composition of lipids and its effect on indices of the nutritional status assessed with the use of somatometric, bioelectric impedance and laboratory methods. The nutrition of students is established to be irrational, unbalanced on the lipid component and creates conditions for the formation of diseases with alimentary dietary risk factors. Traditional indices of nutritional status (BMI, W/HR) at this are within the boundaries of normal values, but the composition of the body under the influence of an excess of animal fats with a deficiency of essential polyunsaturated fatty acids is altering that can be diagnosed with the aid of bioimpedance measuring method. There are established correlation relations between the parameters ofconsumption of dietary lipids and indices of the nutritional status in young adults.

  19. Correlating anomalous diffusion with lipid bilayer membrane structure using single molecule tracking and atomic force microscopy

    Science.gov (United States)

    Skaug, Michael J.; Faller, Roland; Longo, Marjorie L.

    2011-06-01

    Anomalous diffusion has been observed abundantly in the plasma membrane of biological cells, but the underlying mechanisms are still unclear. In general, it has not been possible to directly image the obstacles to diffusion in membranes, which are thought to be skeleton bound proteins, protein aggregates, and lipid domains, so the dynamics of diffusing particles is used to deduce the obstacle characteristics. We present a supported lipid bilayer system in which we characterized the anomalous diffusion of lipid molecules using single molecule tracking, while at the same time imaging the obstacles to diffusion with atomic force microscopy. To explain our experimental results, we performed lattice Monte Carlo simulations of tracer diffusion in the presence of the experimentally determined obstacle configurations. We correlate the observed anomalous diffusion with obstacle area fraction, fractal dimension, and correlation length. To accurately measure an anomalous diffusion exponent, we derived an expression to account for the time-averaging inherent to all single molecule tracking experiments. We show that the length of the single molecule trajectories is critical to the determination of the anomalous diffusion exponent. We further discuss our results in the context of confinement models and the generating stochastic process.

  20. Oxidative stability of structured lipids containing C18:0, C18:1, C18:2, C18:3 or CLA in sn 2-position - as bulk lipids and in milk drinks

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Nielsen, Nina Skall; Xu, Xuebing

    2004-01-01

    In this study, we compared the oxidative stability of a specific structured lipid (SL) containing conjugated linoleic acid (CLA) in the sn2-position with SL containing other C18 fatty acids of different degree of unsaturation (stearic, oleic, linoleic or linolenic acid). SL was produced by enzyma......In this study, we compared the oxidative stability of a specific structured lipid (SL) containing conjugated linoleic acid (CLA) in the sn2-position with SL containing other C18 fatty acids of different degree of unsaturation (stearic, oleic, linoleic or linolenic acid). SL was produced...... by enzymatic interesterification with caprylic acid. Oxidative stability was compared in the five lipids themselves and in milk drinks containing 5% of the different SL. During storage, samples were taken for chemical and physical analyses. Moreover, sensory assessments were performed on milk drinks....... The oxidative stability of our SL was very different when comparing (a) bulk lipids and milk drink and (b) the five different batches of each product. SL based on oleic acid was the most unstable as bulk lipid, while SL based on linoleic acid was the most unstable in milk drink. SL based on CLA was the second...

  1. Perspectives on marine zooplankton lipids

    DEFF Research Database (Denmark)

    Kattner, G.; Hagen, W.; Lee, R.F.

    2007-01-01

    We developed new perspectives to identify important questions and to propose approaches for future research on marine food web lipids. They were related to (i) structure and function of lipids, (ii) lipid changes during critical life phases, (iii) trophic marker lipids, and (iv) potential impact ...

  2. INTERESTERIFIKASI ENZIMATIS MINYAK IKAN DENGAN ASAM LAURAT UNTUK SINTESIS LIPID TERSTRUKTUR [Enzymatic Interesterification of Fish Oil with Lauric Acid for the Synthesis of Structured Lipid

    Directory of Open Access Journals (Sweden)

    Edy Subroto1

    2008-12-01

    Full Text Available Structured lipid (SL containing of medium chain fatty acid (MCFA at outer position and polyunsaturated fatty acid (PUFA at sn-2 position has superior dietary and absorption characteristics. The most methods for the enzymatic synthesis of SL were through two steps process, so that it was inefficient. Caprilic acid was usually used as a source of MCFA. In this research, SL was synthesized by enzymatic interesterification between fish oil and lauric acid. The specific lipase from Mucor miehei was used as catalyzed. Factors, such as the incubation time, substrate mole ratio, and reaction temperature were evaluated. The incorporation and the position of lauric acid on glycerol backbone and glyceride profile were determined. The results showed that SL containing of lauric acid at the outer position and PUFA at sn-2 was successfully synthesized, and it was done through one step process. From regiospecific determination, it showed that the position of lauric acid incorporation was only at the sn-1 and sn-3. Only 0.87% of lauric acid was incorporated at the sn-2. The optimum time and temperature of the reaction, and the substrate mole ratio were 12 h, 50C and 1:10, respectively, in which the incorporation of lauric acid was 62.8% (mol. Glyceride profile was affected by incubation time, substrate mole ratio and reaction temperature. Triglyceride concentration decreased with an increase in the incubation time (> 12 h. In contrast, the diglyceride concentration increased at longer incubation time (> 12 h. Beside, triglyceride concentration increased with an increase in substrate mole ratio to 1:10, but it decreased when mole ratio of substrate was 1:15. At higher temperature (50C, triglyceride decreased with an increase in the reaction temperature. In summary, the SL was successfully synthesized by the interesterification of fish oil and lauric acid using specific lipase of Mucor miehei.

  3. Lipids and lipid binding proteins: a perfect match.

    Science.gov (United States)

    Glatz, Jan F C

    2015-02-01

    Lipids serve a great variety of functions, ranging from structural components of biological membranes to signaling molecules affecting various cellular functions. Several of these functions are related to the unique physico-chemical properties shared by all lipid species, i.e., their hydrophobicity. The latter, however, is accompanied by a poor solubility in an aqueous environment and thus a severe limitation in the transport of lipids in aqueous compartments such as blood plasma and the cellular soluble cytoplasm. Specific proteins which can reversibly and non-covalently associate with lipids, designated as lipid binding proteins or lipid chaperones, greatly enhance the aqueous solubility of lipids and facilitate their transport between tissues and within tissue cells. Importantly, transport of lipids across biological membranes also is facilitated by specific (membrane-associated) lipid binding proteins. Together, these lipid binding proteins determine the bio-availability of their ligands, and thereby markedly influence the subsequent processing, utilization, or signaling effect of lipids. The bio-availability of specific lipid species thus is governed by the presence of specific lipid binding proteins, the affinity of these proteins for distinct lipid species, and the presence of competing ligands (including pharmaceutical compounds). Recent studies suggest that post-translational modifications of lipid binding proteins may have great impact on lipid-protein interactions. As a result, several levels of regulation exist that together determine the bio-availability of lipid species. This short review discusses the significance of lipid binding proteins and their potential application as targets for therapeutic intervention.

  4. Structure of Protein Geranylgeranyltransferase-I from the Human Pathogen Candida albicans Complexed with a Lipid Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Hast, Michael A.; Beese, Lorena S. (Duke)

    2008-11-21

    Protein geranylgeranyltransferase-I (GGTase-I) catalyzes the transfer of a 20-carbon isoprenoid lipid to the sulfur of a cysteine residue located near the C terminus of numerous cellular proteins, including members of the Rho superfamily of small GTPases and other essential signal transduction proteins. In humans, GGTase-I and the homologous protein farnesyltransferase (FTase) are targets of anticancer therapeutics because of the role small GTPases play in oncogenesis. Protein prenyltransferases are also essential for many fungal and protozoan pathogens that infect humans, and have therefore become important targets for treating infectious diseases. Candida albicans, a causative agent of systemic fungal infections in immunocompromised individuals, is one pathogen for which protein prenylation is essential for survival. Here we present the crystal structure of GGTase-I from C. albicans (CaGGTase-I) in complex with its cognate lipid substrate, geranylgeranylpyrophosphate. This structure provides a high-resolution picture of a non-mammalian protein prenyltransferase. There are significant variations between species in critical areas of the active site, including the isoprenoid-binding pocket, as well as the putative product exit groove. These differences indicate the regions where specific protein prenyltransferase inhibitors with antifungal activity can be designed.

  5. Perspectives on marine zooplankton lipids

    DEFF Research Database (Denmark)

    Kattner, G.; Hagen, W.; Lee, R.F.

    2007-01-01

    We developed new perspectives to identify important questions and to propose approaches for future research on marine food web lipids. They were related to (i) structure and function of lipids, (ii) lipid changes during critical life phases, (iii) trophic marker lipids, and (iv) potential impact...... of climate change. The first addresses the role of lipids in membranes, storage lipids, and buoyancy with the following key question: How are the properties of membranes and deposits affected by the various types of lipids? The second deals with the importance of various types of lipids during reproduction......, development, and resting phases and addresses the role of the different storage lipids during growth and dormancy. The third relates to trophic marker lipids, which are an important tool to follow lipid and energy transfer through the food web. The central question is how can fatty acids be used to identify...

  6. Lipid Profile

    Science.gov (United States)

    ... AACC products and services. Advertising & Sponsorship: Policy | Opportunities Lipid Profile Share this page: Was this page helpful? Also ... as: Lipid Panel; Coronary Risk Panel Formal name: Lipid Profile Related tests: Cholesterol ; HDL Cholesterol ; LDL Cholesterol ; Triglycerides ; ...

  7. Lipid exchange by ultracentrifugation

    DEFF Research Database (Denmark)

    Drachmann, Nikolaj Düring; Olesen, Claus

    2014-01-01

    Lipids play an important role in maintaining P-type ATPase structure and function, and often they are crucial for ATPase activity. When the P-type ATPases are in the membrane, they are surrounded by a mix of different lipids species with varying aliphatic chain lengths and saturation......, and the complex interplay between the lipids and the P-type ATPases are still not well understood. We here describe a robust method to exchange the majority of the lipids surrounding the ATPase after solubilisation and/or purification with a target lipid of interest. The method is based on an ultracentrifugation...... step, where the protein sample is spun through a dense buffer containing large excess of the target lipid, which results in an approximately 80-85 % lipid exchange. The method is a very gently technique that maintains protein folding during the process, hence allowing further characterization...

  8. Nutrients and neurodevelopment: lipids.

    Science.gov (United States)

    González, Horacio F; Visentin, Silvana

    2016-10-01

    Nutrients, lipids in particular, make up the central nervous system structure and play major functional roles: they stimulate development, migration, and nerve cell differentiation. They are part of gray matter, white matter, nerve nuclei, and synaptogenesis. Breast milk contains lipids which are crucial for infant brain development. The lipid profile of breast milk was used as a guideline for the development of breast milk substitutes. However, to date, no substitute has matched it. Complementary feeding should include docosahexaenoic acid, arachidonic acid, other polyunsaturated fatty acids, saturated fatty acids, and complex lipids found in milk fat. The lipid composition of breast milk depends on maternal intake and nutritional status during pregnancy and breast-feeding. It has a great impact on development. Our goal is to review scientific literature regarding the role of lipids on infant brain development and the importance of breast milk lipid composition, maternal diet, and complementary feeding.

  9. Peripheral vagus nerve stimulation significantly affects lipid composition and protein secondary structure within dopamine-related brain regions in rats.

    Science.gov (United States)

    Surowka, Artur Dawid; Krygowska-Wajs, Anna; Ziomber, Agata; Thor, Piotr; Chrobak, Adrian Andrzej; Szczerbowska-Boruchowska, Magdalena

    2015-06-01

    Recent immunohistochemical studies point to the dorsal motor nucleus of the vagus nerve as the point of departure of initial changes which are related to the gradual pathological developments in the dopaminergic system. In the light of current investigations, it is likely that biochemical changes within the peripheral nervous system may influence the physiology of the dopaminergic system, suggesting a putative role for it in the development of neurodegenerative disorders. By using Fourier transform infrared microspectroscopy, coupled with statistical analysis, we examined the effect of chronic, unilateral electrical vagus nerve stimulation on changes in lipid composition and in protein secondary structure within dopamine-related brain structures in rats. It was found that the chronic vagal nerve stimulation strongly affects the chain length of fatty acids within the ventral tegmental area, nucleus accumbens, substantia nigra, striatum, dorsal motor nucleus of vagus and the motor cortex. In particular, the level of lipid unsaturation was found significantly increasing in the ventral tegmental area, substantia nigra and motor cortex as a result of vagal nerve stimulation. When it comes to changes in protein secondary structure, we could see that the mesolimbic, mesocortical and nigrostriatal dopaminergic pathways are particularly affected by vagus nerve stimulation. This is due to the co-occurrence of statistically significant changes in the content of non-ordered structure components, alpha helices, beta sheets, and the total area of Amide I. Macromolecular changes caused by peripheral vagus nerve stimulation may highlight a potential connection between the gastrointestinal system and the central nervous system in rat during the development of neurodegenerative disorders.

  10. Molecular Structure-Based Methods of Property Prediction in Application to Lipids: A Review and Refinement

    DEFF Research Database (Denmark)

    Cunico, Larissa; Hukkerikar, Amol; Ceriani, Roberta;

    2013-01-01

    The paper is a review of the combined group contribution (GC)–atom connectivity index (CI) approachfor prediction of physical and thermodynamic properties of organic chemicals and their mixtures withspecial emphasis on lipids. The combined approach employs carefully selected datasets of different...... dependent, have been developed. For mixtures, properties related to phase equilibria aremodeled with GE-based models (UNIQUAC, UNIFAC, NRTL, and combined UNIFAC-CI method). The col-lected phase equilibrium data for VLE and SLE have been tested for thermodynamic consistency togetherwith a performance...... evaluation of the GE-models. The paper also reviews the role of the databases andthe mathematical and thermodynamic consistency of the measured/estimated data and the predictivenature of the developed models....

  11. Structure of the first representative of Pfam family PF09410 (DUF2006) reveals a structural signature of the calycin superfamily that suggests a role in lipid metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Hsiu-Ju; Bakolitsa, Constantina; Skerra, Arne; Lomize, Andrei; Carlton, Dennis; Miller, Mitchell D.; Krishna, S. Sri; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L.; Clayton, Thomas; Deller, Marc C.; Duan, Lian; Feuerhelm, Julie; Grant, Joanna C.; Grzechnik, Slawomir K.; Han, Gye Won; Jaroszewski, Lukasz; Jin, Kevin K.; Klock, Heath E.; Knuth, Mark W.; Kozbial, Piotr; Kumar, Abhinav; Marciano, David; McMullan, Daniel; Morse, Andrew T.; Nigoghossian, Edward; Okach, Linda; Paulsen, Jessica; Reyes, Ron; Rife, Christopher L.; van den Bedem, Henry; Weekes, Dana; Xu, Qingping; Hodgson, Keith O.; Wooley, John; Elsliger, Marc-Andre; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A. (SLAC); (Michigan); (TU Munchen)

    2015-10-15

    The first structural representative of the domain of unknown function DUF2006 family, also known as Pfam family PF09410, comprises a lipocalin-like fold with domain duplication. The finding of the calycin signature in the N-terminal domain, combined with remote sequence similarity to two other protein families (PF07143 and PF08622) implicated in isoprenoid metabolism and the oxidative stress response, support an involvement in lipid metabolism. Clusters of conserved residues that interact with ligand mimetics suggest that the binding and regulation sites map to the N-terminal domain and to the interdomain interface, respectively.

  12. A New Look at Genetic and Environmental Architecture on Lipids Using Non-Normal Structural Equation Modeling in Male Twins: The NHLBI Twin Study.

    Science.gov (United States)

    Wu, Sheng-Hui; Ozaki, Koken; Reed, Terry; Krasnow, Ruth E; Dai, Jun

    2017-07-01

    This study examined genetic and environmental influences on the lipid concentrations of 1028 male twins using the novel univariate non-normal structural equation modeling (nnSEM) ADCE and ACE models. In the best fitting nnSEM ADCE model that was also better than the nnSEM ACE model, additive genetic factors (A) explained 4%, dominant genetic factors (D) explained 17%, and common (C) and unique (E) environmental factors explained 47% and 33% of the total variance of high-density lipoprotein cholesterol (HDL-C). The percentage of variation explained for other lipids was 0% (A), 30% (D), 34% (C) and 37% (E) for low-density lipoprotein cholesterol (LDL-C); 30, 0, 31 and 39% for total cholesterol; and 0, 31, 12 and 57% for triglycerides. It was concluded that additive and dominant genetic factors simultaneously affected HDL-C concentrations but not other lipids. Common and unique environmental factors influenced concentrations of all lipids.

  13. Structural transition in aqueous lipid/bile salt [DPPC/NaDC] supramolecular aggregates: SANS and DLS study

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, M.A. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Janich, M.; Hildebrand, A. [Martin-Luther-University, Halle (Saale) (Germany); Strunz, P. [Berlin Neutron Scattering Center, HZB, Berlin (Germany); Neubert, R.H.H. [Martin-Luther-University, Halle (Saale) (Germany); Lombardo, D., E-mail: lombardo@me.cnr.it [CNR–IPCF, Istituto per i Processi Chimico Fisici – (Sez. Messina), I-98158, Messina (Italy)

    2013-10-16

    Highlights: • Self-assembly in model DPPC lipids and NaDC bile salt by SANS and DLS experiments. • Bile salt creates structural interference against cohesive tendency of DPPC bilayers. • NaDC steric interactions cause transition toward different supramolecular structures. - Abstract: Small angle neutron scattering (SANS) and dynamic light scattering (DLS) were used to study different aggregation states in sodium deoxycholate (NaDC)-phosphatidylcholine systems at T = 60 °C. Size and shape of the aggregates investigated as a function of the NaDC bile salt concentration (at the constant DPPC concentration of 6 mM) indicate a strong dependence of the size and morphology of the generated aggregates on the relative amount of NaDC bile salt. More specifically large occupied area of the bile salt induces a steric interaction which promotes the transition toward a variety of supramolecular structures ranging from ellipsoidal vesicles, ribbon-like structures, up to final spherical mixed micelles at the large amount of bile salt of 10 mM NaDC. The findings of the obtained results give important insight for understanding the formation of different topologies in aqueous lipid–bile salt mixtures as well as stimulate new routes for liposome reconstitution–solubilisation processes suitable for technological applications.

  14. Production of specific-structured lipids by enzymatic interesterification: elucidation of acyl migration by response surface design

    DEFF Research Database (Denmark)

    Xu, Xuebing; Skands, Anja; Høy, Carl-Erik

    1998-01-01

    . The five factors, water content, reaction temperature, enzyme load, reaction time and substrate ratio, were varied at three levels together with two star points. All parameters besides substrate ratio had strong positive influences on acyl migration, and reaction temperature was most significant....... The contour plots clearly show the interactions between the parameters. The migration rates of different fatty acids were also compared from three different sets of experiments during the lipase-catalyzed reaction. The best-fitting quadratic response surface model was determined by regression and backward......Production of specific-structured lipids (SSL) by lipase-catalyzed interesterification has been attracting more and more attention recently. However, it was found that acyl migration occurs during the reaction and causes the production of by-products. In this paper, the elucidation of acyl...

  15. Production of specifically structured lipids by enzymatic interesterification in a pilot enzyme bed reactor: process optimization by response surface methodology

    DEFF Research Database (Denmark)

    Xu, Xuebing; Mu, Huiling; Høy, Carl-Erik

    1999-01-01

    to optimize the reaction system with four process parameters, these being volume flow rate, water content in the substrates, reaction temperature and substrate ratio. The incorporation of acyl donors, product yields and the content of diacylglycerols were measured as the model responses. Enzyme activity......Pilot production of specifically structured lipids by Lipozyme IM-catalyzed interesterification was carried out in a continuous enzyme bed reactor without the use of solvent. Medium chain triacylglycerols and oleic acid were used as model substrates. Response surface methodology was applied...... was not identical for the sequential experiments in the same enzyme bed due to the deactivation of the Lipozyme IM. Therefore, the results were normalized based on enzyme deactivation models. Well-fitting quadratic models were obtained after normalizing the data for the incorporation of oleic acid...

  16. Skeletal muscle structural lipids improve during weight-maintenance after a very low calorie dietary intervention

    Directory of Open Access Journals (Sweden)

    Vaag Allan

    2009-08-01

    Full Text Available Abstract Background The objective was to investigate in a group of obese subjects the course in skeletal muscle phospholipid (SMPL fatty acids (FA during a 24-weeks weight maintenance program, which was preceded by a successful very low calorie dietary intervention (VLCD. Special focus was addressed to SMPL omega-3 FA, which is a lipid entity that influences insulin action. Methods Nine obese subjects (BMI = 35.7 ± 1.0 kg/m2, who had completed an 8 weeks VLCD (weight-loss = -9.7 ± 1.6 kg, P Results HOMA-IR and HbA1c stabilized and SMPL total omega-3 FA, docosahexaenoic acid and ratio of n-3/n-6 polyunsaturated FA increased by 24% (P Conclusion The data are consistent with the notion that greater SMPL omega-3 FA obtained during a weight-maintenance program may play a role for preserving insulin sensitivity and glycemic control being generated during a preceding VLCD.

  17. Empty nano and micro-structured lipid carriers of virgin coconut oil for skin moisturisation.

    Science.gov (United States)

    Noor, Norhayati Mohamed; Khan, Abid Ali; Hasham, Rosnani; Talib, Ayesha; Sarmidi, Mohamad Roji; Aziz, Ramlan; Aziz, Azila Abd

    2016-08-01

    Virgin coconut oil (VCO) is the finest grade of coconut oil, rich in phenolic content, antioxidant activity and contains medium chain triglycerides (MCTs). In this work formulation, characterisation and penetration of VCO-solid lipid particles (VCO-SLP) have been studied. VCO-SLP were prepared using ultrasonication of molten stearic acid and VCO in an aqueous solution. The electron microscopy imaging revealed that VCO-SLP were solid and spherical in shape. Ultrasonication was performed at several power intensities which resulted in particle sizes of VCO-SLP ranged from 0.608 ± 0.002 µm to 44.265 ± 1.870 µm. The particle size was directly proportional to the applied power intensity of ultrasonication. The zeta potential values of the particles were from -43.2 ± 0.28 mV to -47.5 ± 0.42 mV showing good stability. The cumulative permeation for the smallest sized VCO-SLP (0.608 µm) was 3.83 ± 0.01 µg/cm(2) whereas for larger carriers it was reduced (3.59 ± 0.02 µg/cm(2)). It is concluded that SLP have the potential to be exploited as a micro/nano scale cosmeceutical carrying vehicle for improved dermal delivery of VCO.

  18. Electron density analysis of the effects of sugars on the structure of lipid bilayers at low hydration - a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Lenné, T.; Kent, B.; Koster, K.L.; Garvey, C.J.; Bryant, G. (ANSTO); (USD); (ANU); (RMIT)

    2012-02-06

    -saccharides affect the average distance between lipid chains in the bilayer, supporting the predictions of the HFE. In this paper we further investigate the effects of sugars on membrane structure by conducting electron density analysis of recent data. This preliminary analysis sheds additional light onto the effects of sugars on membrane structure.

  19. Cardiolipin Deficiency in Rhodobacter sphaeroides Alters the Lipid Profile of Membranes and of Crystallized Cytochrome Oxidase, but Structure and Function Are Maintained

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xi; Tamot, Banita; Hiser, Carrie; Reid, Gavin E.; Benning, Christoph; Ferguson-Miller, Shelagh (MSU)

    2012-05-08

    Many recent studies highlight the importance of lipids in membrane proteins, including in the formation of well-ordered crystals. To examine the effect of changes in one lipid, cardiolipin, on the lipid profile and the production, function, and crystallization of an intrinsic membrane protein, cytochrome c oxidase, we mutated the cardiolipin synthase (cls) gene of Rhodobacter sphaeroides, causing a >90% reduction in cardiolipin content in vivo and selective changes in the abundances of other lipids. Under these conditions, a fully native cytochrome c oxidase (CcO) was produced, as indicated by its activity, spectral properties, and crystal characteristics. Analysis by MALDI tandem mass spectrometry (MS/MS) revealed that the cardiolipin level in CcO crystals, as in the membranes, was greatly decreased. Lipid species present in the crystals were directly analyzed for the first time using MS/MS, documenting their identities and fatty acid chain composition. The fatty acid content of cardiolipin in R. sphaeroides CcO (predominantly 18:1) differs from that in mammalian CcO (18:2). In contrast to the cardiolipin dependence of mammalian CcO activity, major depletion of cardiolipin in R. sphaeroides did not impact any aspect of CcO structure or behavior, suggesting a greater tolerance of interchange of cardiolipin with other lipids in this bacterial system.

  20. Isolation and Structural Elucidation of Antiproliferative Compounds of Lipidic Fractions from White Shrimp Muscle (Litopenaeus vannamei)

    Science.gov (United States)

    López-Saiz, Carmen-María; Velázquez, Carlos; Hernández, Javier; Cinco-Moroyoqui, Francisco-Javier; Plascencia-Jatomea, Maribel; Robles-Sánchez, Maribel; Machi-Lara, Lorena; Burgos-Hernández, Armando

    2014-01-01

    Shrimp is one of the most popular seafood items worldwide, and has been reported as a source of chemopreventive compounds. In this study, shrimp lipids were separated by solvent partition and further fractionated by semi-preparative RP-HPLC and finally by open column chromatography in order to obtain isolated antiproliferative compounds. Antiproliferative activity was assessed by inhibition of M12.C3.F6 murine cell growth using the MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) assay. The methanolic fraction showed the highest antiproliferative activity; this fraction was separated into 15 different sub-fractions (M1–M15). Fractions M8, M9, M10, M12, and M13 were antiproliferative at 100 µg/mL and they were further tested at lower concentrations. Fractions M12 and M13 exerted the highest growth inhibition with an IC50 of 19.5 ± 8.6 and 34.9 ± 7.3 µg/mL, respectively. Fraction M12 was further fractionated in three sub-fractions M12a, M12b, and M12c. Fraction M12a was identified as di-ethyl-hexyl-phthalate, fraction M12b as a triglyceride substituted by at least two fatty acids (predominantly oleic acid accompanied with eicosapentaenoic acid) and fraction M12c as another triglyceride substituted with eicosapentaenoic acid and saturated fatty acids. Bioactive triglyceride contained in M12c exerted the highest antiproliferative activity with an IC50 of 11.33 ± 5.6 µg/mL. Biological activity in shrimp had been previously attributed to astaxanthin; this study demonstrated that polyunsaturated fatty acids are the main compounds responsible for antiproliferative activity. PMID:25526568

  1. Tetra- and Penta-Cyclic Triterpenes Interaction with Lipid Bilayer Membrane: A Structural Comparative Study.

    Science.gov (United States)

    Abboud, Rola; Charcosset, Catherine; Greige-Gerges, Hélène

    2016-06-01

    The effect of tetracyclic (cortisol, prednisolone, and 9-fluorocortisol acetate) and pentacyclic (uvaol and erythrodiol) triterpenes (TTPs) on the fluidity of dipalmitoyl phosphatidyl choline (DPPC) liposome membrane was investigated by differential scanning calorimetry, Raman spectroscopy, and fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH). Liposomes were prepared in the absence and presence of TTPs at molar ratios DPPC:TTP 100:1, 100:2.5, and 100:10. All the studied TTPs abolished the pre-transition and modified the intensity of the Raman peak at 715 cm(-1) proving the interaction of TTP molecules with the choline head group of phospholipids. An increase in the Raman height intensity ratios of the peaks I 2935/2880, I 2844/2880, and I 1090/1130, giving information about the ratio disorder/order of the alkyl chains, and a decrease of the main transition temperature demonstrated the interaction of TTPs with the alkyl chains. The tetracyclic TTPs produced broadening of the phase transition profile. Besides, a scarcely splitting of the main transition peak was obtained with prednisolone and 9-fluorocortisol acetate. The results of fluorescence depolarization of DPH showed that the studied molecules fluidized the liposomal membrane at 25, 41, and 50 °C. Pentacyclic TTPs, being more hydrophobic than tetracyclic ones, demonstrated higher fluidizing effect than tetracyclic TTPs in the liquid crystalline phase suggesting a deeper incorporation in the lipid bilayer. The presence of a free polar head group at the ring D seems to control the TTP incorporation in the bilayer and consequently its effect on the membrane fluidity.

  2. Lipid droplet pattern and nondroplet-like structure in two fat mutants of Caenorhabditis elegans revealed by coherent anti-Stokes Raman scattering microscopy

    Science.gov (United States)

    Yi, Yung-Hsiang; Chien, Cheng-Hao; Chen, Wei-Wen; Ma, Tian-Hsiang; Liu, Kuan-Yu; Chang, Yu-Sun; Chang, Ta-Chau; Lo, Szecheng J.

    2014-01-01

    Lipid is an important energy source and essential component for plasma and organelle membranes in all kinds of cells. Coherent anti-Stokes Raman scattering (CARS) microscopy is a label-free and nonlinear optical technique that can be used to monitor the lipid distribution in live organisms. Here, we utilize CARS microscopy to investigate the pattern of lipid droplets in two live Caenorhabditis elegans mutants (fat-2 and fat-3). The CARS images showed a striking decrease in the size, number, and content of lipid droplets in the fat-2 mutant but a slight difference in the fat-3 mutant as compared with the wild-type worm. Moreover, a nondroplet-like structure with enhanced CARS signal was detected for the first time in the uterus of fat-2 and fat-3 mutants. In addition, transgenic fat-2 mutant expressing a GFP fusion protein of vitellogenin-2 (a yolk lipoprotein) revealed that the enhanced CARS signal colocalized with the GFP signal, which suggests that the nondroplet-like structure is primarily due to the accumulation of yolk lipoproteins. Together, this study implies that CARS microscopy is a potential tool to study the distribution of yolk lipoproteins, in addition to lipid droplets, in live animals.

  3. Structure and dynamics of lipid monolayers: Implications for enzyme catalysed lipolysis

    DEFF Research Database (Denmark)

    Peters, Günther H.J.; Toxværd, S.; Larsen, N.B.;

    1995-01-01

    We have investigated the role of the substrate on the interfacial activation of Upases by an interdisciplinary study of the structure and dynamics of 1,2-sn dipalmitoylglycerol monolayers at distinct surface pressures. The diglyceride Langmuir film undergoes two phase transitions occurring at 38....

  4. Low density lipoprotein : structure, dynamics, and interactions of apoB-100 with lipids

    NARCIS (Netherlands)

    Murtola, Teemu; Vuorela, Timo A.; Hyvonen, Marja T.; Marrink, Siewert-Jan; Karttunen, Mikko; Vattulainen, Ilpo

    2011-01-01

    Low-density lipoprotein (LDL) transports cholesterol in the bloodstream and plays an important role in the development of cardiovascular diseases, in particular atherosclerosis. Despite its importance to health, the structure of LDL is not known in detail. This is worrying since the lack of LDL's st

  5. Lipase-catalyzed acidolysis of canola oil with caprylic acid to produce medium-, long- and medium-chain-type structured lipids

    DEFF Research Database (Denmark)

    Wang, Yingyao; Xia, Luan; Xu, Xuebing

    2012-01-01

    Lipase-catalyzed acidolysis of canola oil with caprylic acid was performed to produce structured lipids (SLs) containing medium-chain fatty acid (M) at position sn-1,3 and long-chain fatty acid (L) at the sn-2 position in a solvent-free system. Six commercial lipases from different sources were s...

  6. Isolation and structure elucidation of avocado seed (Persea americana) lipid derivatives that inhibit Clostridium sporogenes endospore germination.

    Science.gov (United States)

    Rodríguez-Sánchez, Dariana Graciela; Pacheco, Adriana; García-Cruz, María Isabel; Gutiérrez-Uribe, Janet Alejandra; Benavides-Lozano, Jorge Alejandro; Hernández-Brenes, Carmen

    2013-07-31

    Avocado fruit extracts are known to exhibit antimicrobial properties. However, the effects on bacterial endospores and the identity of antimicrobial compounds have not been fully elucidated. In this study, avocado seed extracts were tested against Clostridium sporogenes vegetative cells and active endospores. Bioassay-guided purification of a crude extract based on inhibitory properties linked antimicrobial action to six lipid derivatives from the family of acetogenin compounds. Two new structures and four compounds known to exist in nature were identified as responsible for the activity. Structurally, most potent molecules shared features of an acetyl moiety and a trans-enone group. All extracts produced inhibition zones on vegetative cells and active endospores. Minimum inhibitory concentrations (MIC) of isolated molecules ranged from 7.8 to 15.6 μg/mL, and bactericidal effects were observed for an enriched fraction at 19.5 μg/mL. Identified molecules showed potential as natural alternatives to additives and antibiotics used by the food and pharmaceutical industries to inhibit Gram-positive spore-forming bacteria.

  7. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures

    Directory of Open Access Journals (Sweden)

    Jaydeep Bhattacharya

    2011-02-01

    Full Text Available Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic system for membrane fabrication and subsequent liposome fusion onto the nanoporous support structure. The resulting bilayer formation is monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers.

  8. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures.

    Science.gov (United States)

    Bhattacharya, Jaydeep; Kisner, Alexandre; Offenhäusser, Andreas; Wolfrum, Bernhard

    2011-01-01

    Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic system for membrane fabrication and subsequent liposome fusion onto the nanoporous support structure. The resulting bilayer formation is monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers.

  9. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures

    OpenAIRE

    2011-01-01

    Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic...

  10. Structure-activity relationships of ω-Agatoxin IVA in lipid membranes.

    Science.gov (United States)

    Ryu, Jae Ha; Jung, Hoi Jong; Konishi, Shiro; Kim, Ha Hyung; Park, Zee-Yong; Kim, Jae Il

    2017-01-01

    To analyze structural features of ω-Aga IVA, a gating modifier toxin from spider venom, we here investigated the NMR solution structure of ω-Aga IVA within DPC micelles. Under those conditions, the Cys-rich central region of ω-Aga IVA still retains the inhibitor Cys knot motif with three short antiparallel β-strands seen in water. However, (15)N HSQC spectra of ω-Aga IVA within micelles revealed that there are radical changes to the toxin's C-terminal tail and several loops upon binding to micelles. The C-terminal tail of ω-Aga IVA appears to assume a β-turn like conformation within micelles, though it is disordered in water. Whole-cell patch clamp studies with several ω-Aga IVA analogs indicate that both the hydrophobic C-terminal tail and an Arg patch in the core region of ω-Aga IVA are critical for Cav2.1 blockade. These results suggest that the membrane environment stabilizes the structure of the toxin, enabling it to act in a manner similar to other gating modifier toxins, though its mode of interaction with the membrane and the channel is unique. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. An Evaluation of the Crystal Structure of C-terminal Truncated Apolipoprotein A-I in Solution Reveals Structural Dynamics Related to Lipid Binding.

    Science.gov (United States)

    Melchior, John T; Walker, Ryan G; Morris, Jamie; Jones, Martin K; Segrest, Jere P; Lima, Diogo B; Carvalho, Paulo C; Gozzo, Fábio C; Castleberry, Mark; Thompson, Thomas B; Davidson, W Sean

    2016-03-04

    Apolipoprotein (apo) A-I mediates many of the anti-atherogenic functions attributed to high density lipoprotein. Unfortunately, efforts toward a high resolution structure of full-length apoA-I have not been fruitful, although there have been successes with deletion mutants. Recently, a C-terminal truncation (apoA-I(Δ185-243)) was crystallized as a dimer. The structure showed two helical bundles connected by a long, curved pair of swapped helical domains. To compare this structure to that existing under solution conditions, we applied small angle x-ray scattering and isotope-assisted chemical cross-linking to apoA-I(Δ185-243) in its dimeric and monomeric forms. For the dimer, we found evidence for the shared domains and aspects of the N-terminal bundles, but not the molecular curvature seen in the crystal. We also found that the N-terminal bundles equilibrate between open and closed states. Interestingly, this movement is one of the transitions proposed during lipid binding. The monomer was consistent with a model in which the long shared helix doubles back onto the helical bundle. Combined with the crystal structure, these data offer an important starting point to understand the molecular details of high density lipoprotein biogenesis.

  12. Structure and Dynamics Studies of Cytolytic Peptides in Lipid Bilayers using NMR Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh

    2015-01-01

    different and cytolytic peptides were investigated in this work. The peptides were SPF-5506-A4 from Trichoderma sp, Conolysin-Mt1 from Conus mustelinus, and Alamethicin from Trichoderma viride. The studies employed solution and solid-state NMR spectroscopy in combination with different biophysical methods......- and 2H-labelled peptides. While the solution NMR experiments were performed to determine the structure of SPF-5506-A4 and Conolysin-Mt1, the oriented solid-state NMR experiments served to derive information about the orientation of the peptides with respect to the bilayer normal in order to understand...

  13. X-ray reflectivity investgation of structure and kinetics of photoswitchable lipid monolayers

    DEFF Research Database (Denmark)

    Chatterjee, Kuntal; Haushahn, Björn; Shen, Chen;

    The mechanical and dynamic properties of phospholipid membranes are of importance for important biological functions, such as switching of embedded proteins. In order to investigate these properties we study model systems in which amphiphilic photoswitchable molecules are integrated into Langmuir...... transand cis-conformation by illumination with UV and blue light. We have followed the structural changes in this model membrane and the switching kinetics of the system with Langmuir isotherms and in situ X-ray reflectivity at the LISA diffractometer P08, PETRA III....

  14. X-ray reflectivity investgation of structure and kinetics of photoswitchable lipid monolayers

    DEFF Research Database (Denmark)

    Chatterjee, Kuntal; Haushahn, Björn; Shen, Chen;

    The mechanical and dynamic properties of phospholipid membranes are of importance for important biological functions, such as switching of embedded proteins. In order to investigate these properties we study model systems in which amphiphilic photoswitchable molecules are integrated into Langmuir......- and cis-conformation by illumination with UV and blue light. We have followed the structural changes in this model membrane and the switching kinetics of the system with Langmuir isotherms and in situ X-ray reflectivity at the LISA diffractometer P08, PETRA III....

  15. Structure and Dynamics Studies of Cytolytic Peptides in Lipid Bilayers using NMR Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh

    2015-01-01

    Millions of people around the world take antimicrobial drugs every day to fight off bacterial infections. However, the microbes are starting to fight back and to develop resistance towards conventional antibiotics, posing a major challenge in the future. Therefore, there is a need for exploring...... the opportunities for alternative drugs that cannot be overcome by the bacteria. In this context, cytolytic peptides are being investigated and designed to target cell membranes of microbes specifically. In the search for information about the structure and dynamics of membrane-active peptides, three highly...... to characterize different properties of these peptides. Owing to the membrane-active nature of all three, the peptides were studied in model membranes including isotropic bicelles, magnetically aligned bilayers and mechanically aligned bilayers, employing a diverse set of NMR experiments on unlabeled and 15N...

  16. Effect of biocompatible polymers on the structural integrity of lipid bilayers under external stimuli

    Science.gov (United States)

    Wang, Jia-Yu; Kausik, Ravinath; Chen, Chi-Yuan; Han, Song-I.; Marks, Jeremy; Lee, Ka Yee

    2010-03-01

    Cell membrane dysfunction due to loss of structural integrity is the pathology of tissue death in trauma and common diseases. It is now established that certain biocompatible polymers, such as Poloxamer 188, Poloxamine 1107 and polyethylene glycol (PEG), are effective in sealing of injured cell membranes, and able to prevent acute necrosis. Despite these broad applications of these polymers for human health, the fundamental mechanisms by which these polymers interact with cell membranes are still under debate. Here, the effects of a group of biocompatible polymers on phospholipid membrane integrity under osmotic and oxidative stress were explored using giant unilamellar vesicles as model cell membranes. Our results suggest that the adsorption of the polymers on the membrane surface is responsible for the cell membrane resealing process due to its capability of slowing down the surface hydration dynamics.

  17. Physicochemical properties of structured phosphatidylcholine in drug carrier lipid emulsions for drug delivery systems.

    Science.gov (United States)

    Kawaguchi, Emi; Shimokawa, Ken-ichi; Ishii, Fumiyoshi

    2008-03-15

    Drug carrier emulsions were prepared with structured phosphatidylcholine (PC-LM) which has both a long hydrocarbon chain and a medium hydrocarbon chain, and the characteristics of PC-LM as an emulsifier were investigated by measuring the creaming ratio, the surface tension of the emulsion system, and the mean particle size and zeta potential of the oil droplets in emulsions. The emulsion prepared with PC-LM as an emulsifier kept the condition and the ratio of separation was lower than those with purified egg yolk lecithin (PEL). The mean particle size of the emulsion prepared with PC-LM was smaller than that with PEL when using only sonication, approximately 250 nm. When using a high-pressure homogenizer after sonication, the mean emulsion size with PC-LM was also smaller than with PEL, approximately 150 nm. The surface tension of the various emulsions and the zeta potential of the emulsion droplets were measured to investigate the stability of the systems. In emulsions with PC-LM or PEL, the surface tension as an index of stability increased as the pressure of the homogenizer increased. Moreover, the zeta potential of the emulsion droplets prepared with PC-LM also increased with an increase in pressure of the homogenizer. As a result, it was found that the drug carrier emulsion prepared with PC-LM had significant advantages in terms of stability and mean diameter. We considered it could be used for the preparations of nanoparticle dispersion systems in drug delivery systems.

  18. Bilayer Structure and Lipid Dynamics in a Model Stratum Corneum with Oleic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Hoopes, Matthew I.; Noro, Massimo G.; Longo, Marjorie L.; Faller, Roland

    2011-03-31

    The stratum corneum is the uppermost layer of the skin and acts as a barrier to keep out contaminants and retain moisture. Understanding the molecular structure and behavior of this layer will provide guidance for optimizing its biological function. In this study we use a model mixture comprised of equimolar portions of ceramide NS (24:0), lignoceric acid, and cholesterol to model the effect of the addition of small amounts of oleic acid to the bilayer at 300 and 340 K. Five systems at each temperature have been simulated with concentrations between 0 and 0.1 mol % oleic acid. Our major finding is that subdiffusive behavior over the 200 ns time scale is evident in systems at 340 K, with cholesterol diffusion being enhanced with increased oleic acid. Importantly, cholesterol and other species diffuse faster when radial densities indicate nearest neighbors include more cholesterol. We also find that, with the addition of oleic acid, the bilayer midplane and interfacial densities are reduced and there is a 3% decrease in total thickness occurring mostly near the hydrophilic interface at 300 K with reduced overall density at 340 K. Increased interdigitation occurs independent of oleic acid with a temperature increase. Slight ordering of the long non-hydroxy fatty acid of the ceramide occurs near the hydrophilic interface as a function of the oleic acid concentration, but no significant impact on hydrogen bonding is seen in the chosen oleic acid concentrations.

  19. Structural Dynamics of an Isolated-Voltage Sensor Domain in Lipid Bilayer

    Science.gov (United States)

    Chakrapani, Sudha; Cuello, Luis G.; Cortes, Marien D.; Perozo, Eduardo

    2009-01-01

    Summary A strong interplay between the voltage-sensor domain (VSD) and the pore domain (PD) underlies voltage-gated channel functions. In a few voltage-sensitive proteins, the VSD has been shown to function without a canonical PD, although its structure and oligomeric state remain unknown. Here using EPR spectroscopy we show that the isolated-VSD of KvAP can remain monomeric in reconstituted bilayer and retain a transmembrane conformation. We find that water-filled crevices extend deep into the membrane around S3, a scaffold conducive to transport of proton/cations is intrinsic to the VSD. Differences in solvent accessibility in comparison to the full-length KvAP, allowed us to define an interacting footprint of the PD on the VSD. This interaction is centered around S1 and S2 and shows a rotation of 70–100° relative to Kv1.2-Kv2.1 chimera. Sequence-conservation patterns in Kv channels, Hv channels and voltage-sensitive phosphatases reveal several near-universal features suggesting a common molecular architecture for all VSDs. PMID:18334215

  20. Probing the Structure of the Mechanosensitive Channel of Small Conductance in Lipid Bilayers with Pulsed Electron-Electron Double Resonance

    Science.gov (United States)

    Ward, Richard; Pliotas, Christos; Branigan, Emma; Hacker, Christian; Rasmussen, Akiko; Hagelueken, Gregor; Booth, Ian R.; Miller, Samantha; Lucocq, John; Naismith, James H.; Schiemann, Olav

    2014-01-01

    Mechanosensitive channel proteins are important safety valves against osmotic shock in bacteria, and are involved in sensing touch and sound waves in higher organisms. The mechanosensitive channel of small conductance (MscS) has been extensively studied. Pulsed electron-electron double resonance (PELDOR or DEER) of detergent-solubilized protein confirms that as seen in the crystal structure, the outer ring of transmembrane helices do not pack against the pore-forming helices, creating an apparent void. The relevance of this void to the functional form of MscS in the bilayer is the subject of debate. Here, we report PELDOR measurements of MscS reconstituted into two lipid bilayer systems: nanodiscs and bicelles. The distance measurements from multiple mutants derived from the PELDOR data are consistent with the detergent-solution arrangement of the protein. We conclude, therefore, that the relative positioning of the transmembrane helices is preserved in mimics of the cell bilayer, and that the apparent voids are not an artifact of detergent solution but a property of the protein that will have to be accounted for in any molecular mechanism of gating. PMID:24559986

  1. Synthesis and Applications of Structured Lipids%结构脂质的合成及应用

    Institute of Scientific and Technical Information of China (English)

    钟凯; 葛赞; 计晓黎; 吴维高

    2015-01-01

    结构脂质(SLs)是一类具有营养性和功能性的甘油三酯。对结构脂质的合成方法(酯交换法、酸解法和二步法)和几种常见结构脂质(中碳链甘油三酯、中长碳链甘油三酯、类可可脂、人造母乳、磷酸甘油酯、酚酸甘油酯)的应用进行了综述。%Structured lipids(SLs)is a kind of nutritional and functional triglyceride.The synthetic methods of SLs including transesterification method,acidolysis method and two-step method are reviewed.The applica-tions of some SLs,such as medium chain triglyceride,medium and long chain triglyceride,cocoa butter equiva-lents,human milk fat substitutes,phospholipid,mycophenolipid are discussed.

  2. Thermal transitions in serum amyloid A in solution and on the lipid: implications for structure and stability of acute-phase HDL[S

    Science.gov (United States)

    Jayaraman, Shobini; Haupt, Christian; Gursky, Olga

    2015-01-01

    Serum amyloid A (SAA) is an acute-phase protein that circulates mainly on plasma HDL. SAA interactions with its functional ligands and its pathogenic deposition in reactive amyloidosis depend, in part, on the structural disorder of this protein and its propensity to oligomerize. In vivo, SAA can displace a substantial fraction of the major HDL protein, apoA-I, and thereby influence the structural remodeling and functions of acute-phase HDL in ways that are incompletely understood. We use murine SAA1.1 to report the first structural stability study of human plasma HDL that has been enriched with SAA. Calorimetric and spectroscopic analyses of these and other SAA-lipid systems reveal two surprising findings. First, progressive displacement of the exchangeable fraction of apoA-I by SAA has little effect on the structural stability of HDL and its fusion and release of core lipids. Consequently, the major determinant for HDL stability is the nonexchangeable apoA-I. A structural model explaining this observation is proposed, which is consistent with functional studies in acute-phase HDL. Second, we report an α-helix folding/unfolding transition in SAA in the presence of lipid at near-physiological temperatures. This new transition may have potentially important implications for normal functions of SAA and its pathogenic misfolding. PMID:26022803

  3. Infrared spectroscopy used to determine effects of chia and olive oil incorporation strategies on lipid structure of reduced-fat frankfurters.

    Science.gov (United States)

    Herrero, A M; Ruiz-Capillas, C; Pintado, T; Carmona, P; Jimenez-Colmenero, F

    2017-04-15

    This article reports an infrared spectroscopic study, using attenuated total reflectance (ATR-FTIR), on the structural characteristics of lipids in frankfurters as affected by different strategies to replace animal fat with chia flour and olive oil. Three incorporation strategies were considered: direct addition (FCO) and addition in a conventional emulsion (non-gelled) (FCE) or an emulsion gel using alginate as a gelling agent (FCEG). Reduced-fat (all-pork-fat) frankfurters (FP) were used as reference. Proximate composition and specific technological properties (pH, processing loss, texture) were also evaluated. FCE and FCEG frankfurters showed a shift to higher frequencies and the highest (p<0.05) half-bandwidth in the νasCH2 and νsCH2 bands. These spectroscopic results could be related to the fact that the lipid chain was more disorderly in these samples, presumably because there were more lipid interactions than in the reference frankfurter. These features of lipid structure correlated significantly with processing loss and textural behaviour.

  4. NMR structure of rALF-Pm3, an anti-lipopolysaccharide factor from shrimp: model of the possible lipid A-binding site.

    Science.gov (United States)

    Yang, Yinshan; Boze, Hélène; Chemardin, Patrick; Padilla, André; Moulin, Guy; Tassanakajon, Anchalee; Pugnière, Martine; Roquet, Françoise; Destoumieux-Garzón, Delphine; Gueguen, Yannick; Bachère, Evelyne; Aumelas, André

    2009-03-01

    The anti-lipopolysaccharide factor ALF-Pm3 is a 98-residue protein identified in hemocytes from the black tiger shrimp Penaeus monodon. It was expressed in Pichia pastoris from the constitutive glyceraldehyde-3-phosphate dehydrogenase promoter as a folded and (15)N uniformly labeled rALF-Pm3 protein. Its 3D structure was established by NMR and consists of three alpha-helices packed against a four-stranded beta-sheet. The C(34)-C(55) disulfide bond was shown to be essential for the structure stability. By using surface plasmon resonance, we demonstrated that rALF-Pm3 binds to LPS, lipid A and to OM-174, a soluble analogue of lipid A. Biophysical studies of rALF-Pm3/LPS and rALF-Pm3/OM-174 complexes indicated rather high molecular sized aggregates, which prevented us to experimentally determine by NMR the binding mode of these lipids to rALF-Pm3. However, on the basis of striking structural similarities to the FhuA/LPS complex, we designed an original model of the possible lipid A-binding site of ALF-Pm3. Such a binding site, located on the ALF-Pm3 beta-sheet and involving seven charged residues, is well conserved in ALF-L from Limulus polyphemus and in ALF-T from Tachypleus tridentatus. In addition, our model is in agreement with experiments showing that beta-hairpin synthetic peptides corresponding to ALF-L beta-sheet bind to LPS. Delineating lipid A-binding site of ALFs will help go further in the de novo design of new antibacterial or LPS-neutralizing drugs.

  5. Dynamic molecular structure of DPPC-DLPC-cholesterol ternary lipid system by spin-label electron spin resonance.

    Science.gov (United States)

    Chiang, Yun-Wei; Shimoyama, Yuhei; Feigenson, Gerald W; Freed, Jack H

    2004-10-01

    The hydrated ternary lamellar lipid mixture of dipalmitoyl-PC/dilauroyl-PC/cholesterol (DPPC/DLPC/Chol) has been studied by electron spin resonance (ESR) to reveal the dynamic structure on a molecular level of the different phases that exist and coexist over virtually the full range of composition. The spectra for more than 100 different compositions at room temperature were analyzed by nonlinear least-squares fitting to provide the rotational diffusion rates and order parameters of the end-chain labeled phospholipid 16-PC. The ESR spectra exhibit substantial variation as a function of composition, even though the respective phases generally differ rather modestly from each other. The Lalpha and Lbeta phases are clearly distinguished, with the former exhibiting substantially lower ordering and greater motional rates, whereas the well-defined Lo phase exhibits the greatest ordering and relatively fast motional rates. Typically, smaller variations occur within a given phase. The ESR spectral analysis also yields phase boundaries and coexistence regions which are found to be consistent with previous results from fluorescence methods, although new features are found. Phase coexistence regions were in some cases confirmed by observing the existence of isosbestic points in the absorption mode ESR spectra from the phases. The dynamic structural properties of the DPPC-rich Lbeta and DLPC-rich Lalpha phases, within their two-phase coexistence region do not change with composition along a tie-line, but the ratio of the two phases follows the lever rule in accordance with thermodynamic principles. The analysis shows that 16-PC spin-label partitions nearly equally between the Lalpha and Lbeta phases, making it a useful probe for studying such coexisting phases. Extensive study of two-phase coexistence regions requires the determination of tie-lines, which were approximated in this study. However, a method is suggested to accurately determine the tie-lines by ESR.

  6. Structure of the body-centered cubic phase of lipid systems does not consist of indefinitely long straight rods

    OpenAIRE

    Luzzati, Vittorio; Tardieu, Annette; Gulik-Krzywicki, Tadeusz

    1981-01-01

    The observed intensities of the reflections from the body-centered cubic phase of lipid systems are shown to be incompatible with a recently reported model consisting of straight, indefinitely long rods.

  7. Modification of structure and pattern of lipid monolayer on water and solid surfaces in presence of globular protein

    Science.gov (United States)

    Sah, Bijay Kumar; Kundu, Sarathi

    2017-05-01

    Langmuir monolayers of phospholipids at the air-water interface are well-established model systems for mimicking biological membranes and hence are useful for studying lipid-protein interactions. In the present work, phases and phase transformations occurring in the lipid (DMPA) monolayer in the presence of globular protein (BSA) at neutral subphase pH (≈7.0) are highlighted and the corresponding in-plane pattern and morphology are explored from the surface pressure (π) - specific molecular area (A) isotherm, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) both at air-water and air-solid interfaces. Films of pure lipid and lipid-protein complexes are deposited on solid surfaces by Langmuir-Blodgett method. Due to the presence of BSA molecules, phases and domain pattern changes in comparison with that of the pure DMPA. Moreover, accumulations of globular proteins in between lipid domains are also visible through BAM. AFM shows that the mixed film has relatively bigger globular-like morphology in comparison with that of pure DMPA domains. Combination of electrostatic and hydrophobic interactions between protein and lipid are responsible for such modifications.

  8. Regulation of lipid metabolism

    Institute of Scientific and Technical Information of China (English)

    Peng LI

    2011-01-01

    @@ Lipids including cholesterol, phospholipids, fatty acids and triacylglycerols are important cellular constituents involved in membrane structure, energy homeostasis and many biological processes such as signal transduction, organelle development and cell differentiation.Recently, the area of lipid metabolism has drawn a great deal of attention due to its emerging role in the development of metabolic disorders such as obesity, diabetes, atherosclerosis and liver steatosis.We decided to organize a special issue of Frontiers in Biology focusing on our current understanding of lipid metabolism.

  9. Lipid profile and nutritional intake in children and adolescents with Type 1 diabetes improve after a structured dietician training to a Mediterranean-style diet.

    Science.gov (United States)

    Cadario, F; Prodam, F; Pasqualicchio, S; Bellone, S; Bonsignori, I; Demarchi, I; Monzani, A; Bona, G

    2012-02-01

    To evaluate if nutritional intakes and lipid profile fulfill international guidelines and recommendations before and after a structured dietician training to a Mediterranean- style diet in an Italian pediatric population with Type 1 diabetes. A 6-month prospective cohort study. Baseline and after-intervention nutritional intakes, lipid profile, glycated hemoglobin (HbA(1c)), and clinical parameters of 96 children and adolescents with Type 1 diabetes were assessed. A comparative computerized system which was approved and validated by the Italian Diabetologist Association was used to define the amounts of nutrients. At baseline mean daily dietary intakes of carbohydrates, proteins, and lipids were respectively (mean ± SEM) 51.8 ± 0.5, 15.9 ± 0.2, 33.8 ± 0.6%, with a contribution of cholesterol of 248.7 ± 12.5 mg/day. Fiber assumption was 18.0 ± 0.4 g/day. The 64.5% and 29.1% (plipid parameter higher than 75(th) and 95(th) percentiles, respectively, of selected cut points (American Diabetes Association guidelines for total and LDL-cholesterol and American Academy of Pediatrics standards for HDL-cholesterol and triglycerides). Six months after the dietician intervention, dietary lipids and cholesterol decreased (plipid parameter (plipids intake and a suboptimal lipid profile. A structured dietician training to a Mediterranean-style diet improves the quality of nutrient intakes being followed by a reduction of LDL-cholesterol, non- HDL-cholesterol, and total cholesterol:HDL-cholesterol ratios.

  10. Univariate and multivariate molecular spectral analyses of lipid related molecular structural components in relation to nutrient profile in feed and food mixtures

    Science.gov (United States)

    Abeysekara, Saman; Damiran, Daalkhaijav; Yu, Peiqiang

    2013-02-01

    The objectives of this study were (i) to determine lipid related molecular structures components (functional groups) in feed combination of cereal grain (barley, Hordeum vulgare) and wheat (Triticum aestivum) based dried distillers grain solubles (wheat DDGSs) from bioethanol processing at five different combination ratios using univariate and multivariate molecular spectral analyses with infrared Fourier transform molecular spectroscopy, and (ii) to correlate lipid-related molecular-functional structure spectral profile to nutrient profiles. The spectral intensity of (i) CH3 asymmetric, CH2 asymmetric, CH3 symmetric and CH2 symmetric groups, (ii) unsaturation (Cdbnd C) group, and (iii) carbonyl ester (Cdbnd O) group were determined. Spectral differences of functional groups were detected by hierarchical cluster analysis (HCA) and principal components analysis (PCA). The results showed that the combination treatments significantly inflicted modifications (P spectroscopy. These changes were associated with nutrient profiles and functionality.

  11. [Influence of wholemeal bread on functional and structure characteristics erythrocytes membrane and lipids oxidation in fraction of microsome of internal organs in rats].

    Science.gov (United States)

    Vitavskaia, A V; Khasiev, Kh Kh; Murzakhmetova, M K

    2006-01-01

    Acute tests in rats showed, that application of wholemeal bread into a standard vivarium ration (40 g per a rat with body weight 180-200 g) drastically impoves structural and functional characteristics of membranes of erlthrocytes and cells of a number of internal organs. Anhibition of peroxide oxidation of biological membranes lipids of internal organs (liver, ridneys, heart, lungs and brain) takes place, as well as impairment of erythrocytes membranes perkeability and increase of their peroxide resistivity.

  12. MLM型结构脂质的安全性评价——致畸试验%Safety Evaluation of MLM's Structured Lipid-Teratogenicity Test

    Institute of Scientific and Technical Information of China (English)

    郭咪咪; 王瑛瑶; 栾霞

    2016-01-01

    Objective:To study toxicological safety of MLM (M:medium chain fatty acid;L:long chain fatty acid) structured lipid through the teratogenicity test.Methods:Teratogenicity test of rat were carried out to evaluate this structured lipid safety when the 100 times,the 150 times and the 200 times the daily recommended dose of it in people were fed respectively.Results:The weight increment of pregnant rats,the early embryonic development,the growth and development of fetal rats,the development of the fetal rats' bones and internal organs were no significant effects due to each dose group of MLM structured lipid.Conclusion:there were no teratogenic effect to the rats from the MLM structured lipid in that dose range according to teratogenicity test in relevant standards.%目的:通过研究MLM(中碳链-长碳链-中碳链)型结构脂质的致畸性,了解其毒理学安全性.方法:分别以人体每日推荐量的10,150,200倍的MLM型结构脂质制备饲料并喂养孕鼠,通过对大鼠的致畸试验对其安全性评价.结果:MLM型结构脂质各剂量组对孕鼠体重的增长,胚胎早期发育及胎鼠的生长发育,骨骼和内脏发育均无明显影响.结论:根据相关标准中致畸试验结果判定,在试验剂量范围MLM型结构脂质对大鼠无致畸作用.

  13. Lipid domains in bicelles containing unsaturated lipids and cholesterol.

    Science.gov (United States)

    Cho, Hyo Soon; Dominick, Johnna L; Spence, Megan M

    2010-07-22

    We have created a stable bicelle system capable of forming micrometer-scale lipid domains that orient in a magnetic field, suitable for structural biology determination in solid-state NMR. The bicelles consisted of a mixture of cholesterol, saturated lipid (DMPC), and unsaturated lipid (POPC), a mixture commonly used to create domains in model membranes, along with a short chain lipid (DHPC) that allows formation of the bicelle phase. While maintaining a constant molar ratio of long to short chain lipids, q = ([POPC]+[DMPC])/[DHPC] = 3, we varied the concentrations of the unsaturated lipid, POPC, and cholesterol to observe the effects of the components on bicelle stability. Using (31)P solid-state NMR, we observed that unsaturated lipids (POPC) greatly destabilized the alignment of the membranes in the magnetic field, while cholesterol stabilized their alignment. By combining cholesterol and unsaturated lipids in the bicelles, we created membranes aligning uniformly in the magnetic field, despite very high concentrations of unsaturated lipids. These bicelles, with high concentrations of both cholesterol and unsaturated lipid, showed similar phase behavior to bicelles commonly used in structural biology, but aligned over a wider temperature range (291-314 K). Domains were observed by measuring time-dependent diffusion constants reflecting restricted diffusion of the lipids within micrometer-scale regions of the bicelles. Micron-scale domains have never been observed in POPC/DMPC/cholesterol vesicles, implying that bilayers in bicelles show different phase behavior than their counterparts in vesicles, and that bilayers in bicelles favor domain formation.

  14. Comparison of the oral bioavailability of silymarin-loaded lipid nanoparticles with their artificial lipolysate counterparts: implications on the contribution of integral structure.

    Science.gov (United States)

    Shangguan, Mingzhu; Qi, Jianping; Lu, Yi; Wu, Wei

    2015-07-15

    Both solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were artificially broken down into lipolysates. Their oral bioavailability, with silymarin as a model drug, was compared in dogs to highlight the contribution of their integral structure. The lipid nanoparticles were prepared using a conventional hot homogenization method, whereas the lipolysates were obtained through lipolysis in phospholipid- and bile salt-enriched simulated intestinal fluid. More than 80% of vehicle-associated drugs could be transformed into the water-soluble form of mixed micelles. Pharmacokinetics analysis in dogs showed a decrease in bioavailability of 74.86% and 59.09% for lipolysates compared to integral NLCs and SLNs, respectively. It was indicated that lipolysates contributed to a majority of drug absorption. Integral nanoparticles were superior to their lipolysate counterparts, but only marginally; if the approximately 20% of the drug that precipitated during in vitro lipolysis was deducted from the overall absorption amount, the superiority of integral nanoparticles would be significantly compromised. In conclusion, lipolysis was the predominant in vivo absorption mechanism, and the contribution of intact lipid nanoparticles was limited. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. The structure of the CD3 ζζ transmembrane dimer in POPC and raft-like lipid bilayer: a molecular dynamics study.

    Science.gov (United States)

    Petruk, Ariel Alcides; Varriale, Sonia; Coscia, Maria Rosaria; Mazzarella, Lelio; Merlino, Antonello; Oreste, Umberto

    2013-11-01

    Plasma membrane lipids significantly affect assembly and activity of many signaling networks. The present work is aimed at analyzing, by molecular dynamics simulations, the structure and dynamics of the CD3 ζζ dimer in palmitoyl-oleoyl-phosphatidylcholine bilayer (POPC) and in POPC/cholesterol/sphingomyelin bilayer, which resembles the raft membrane microdomain supposed to be the site of the signal transducing machinery. Both POPC and raft-like environment produce significant alterations in structure and flexibility of the CD3 ζζ with respect to nuclear magnetic resonance (NMR) model: the dimer is more compact, its secondary structure is slightly less ordered, the arrangement of the Asp6 pair, which is important for binding to the Arg residue in the alpha chain of the T cell receptor (TCR), is stabilized by water molecules. Different interactions of charged residues with lipids at the lipid-cytoplasm boundary occur when the two environments are compared. Furthermore, in contrast to what is observed in POPC, in the raft-like environment correlated motions between transmembrane and cytoplasmic regions are observed. Altogether the data suggest that when the TCR complex resides in the raft domains, the CD3 ζζ dimer assumes a specific conformation probably necessary to the correct signal transduction.

  16. Structure of Yeast OSBP-Related Protein Osh1 Reveals Key Determinants for Lipid Transport and Protein Targeting at the Nucleus-Vacuole Junction.

    Science.gov (United States)

    Manik, Mohammad Kawsar; Yang, Huiseon; Tong, Junsen; Im, Young Jun

    2017-03-10

    Yeast Osh1 belongs to the oxysterol-binding protein (OSBP) family of proteins and contains multiple targeting modules optimized for lipid transport at the nucleus-vacuole junction (NVJ). The key determinants for NVJ targeting and the role of Osh1 at NVJs have remained elusive because of unknown lipid specificities. In this study, we determined the structures of the ankyrin repeat domain (ANK), and OSBP-related domain (ORD) of Osh1, in complex with Nvj1 and ergosterol, respectively. The Osh1 ANK forms a unique bi-lobed structure that recognizes a cytosolic helical segment of Nvj1. We discovered that Osh1 ORD binds ergosterol and phosphatidylinositol 4-phosphate PI(4)P in a competitive manner, suggesting counter-transport function of the two lipids. Ergosterol is bound to the hydrophobic pocket in a head-down orientation, and the structure of the PI(4)P-binding site in Osh1 is well conserved. Our results suggest that Osh1 performs non-vesicular transport of ergosterol and PI(4)P at the NVJ.

  17. Quantitative structure-activity relationships predicting the antioxidant potency of 17β-estradiol-related polycyclic phenols to inhibit lipid peroxidation.

    Science.gov (United States)

    Prokai, Laszlo; Rivera-Portalatin, Nilka M; Prokai-Tatrai, Katalin

    2013-01-11

    The antioxidant potency of 17β-estradiol and related polycyclic phenols has been well established. This property is an important component of the complex events by which these types of agents are capable to protect neurons against the detrimental consequences of oxidative stress. In order to relate their molecular structure and properties with their capacity to inhibit lipid peroxidation, a marker of oxidative stress, quantitative structure-activity relationship (QSAR) studies were conducted. The inhibition of Fe3+-induced lipid peroxidation in rat brain homogenate, measured through an assay detecting thiobarbituric acid reactive substances for about seventy compounds were correlated with various molecular descriptors. We found that lipophilicity (modeled by the logarithm of the n-octanol/water partition coefficient, logP) was the property that influenced most profoundly the potency of these compounds to inhibit lipid peroxidation in the biological medium studied. Additionally, the important contribution of the bond dissociation enthalpy of the phenolic O-H group, a shape index, the solvent-accessible surface area and the energy required to remove an electron from the highest occupied molecular orbital were also confirmed. Several QSAR equations were validated as potentially useful exploratory tools for identifying or designing novel phenolic antioxidants incorporating the structural backbone of 17β-estradiol to assist therapy development against oxidative stress-associated neurodegeneration.

  18. Quantitative Structure-Activity Relationships Predicting the Antioxidant Potency of 17β-Estradiol-Related Polycyclic Phenols to Inhibit Lipid Peroxidation

    Directory of Open Access Journals (Sweden)

    Katalin Prokai-Tatrai

    2013-01-01

    Full Text Available The antioxidant potency of 17β-estradiol and related polycyclic phenols has been well established. This property is an important component of the complex events by which these types of agents are capable to protect neurons against the detrimental consequences of oxidative stress. In order to relate their molecular structure and properties with their capacity to inhibit lipid peroxidation, a marker of oxidative stress, quantitative structure-activity relationship (QSAR studies were conducted. The inhibition of Fe3+-induced lipid peroxidation in rat brain homogenate, measured through an assay detecting thiobarbituric acid reactive substances for about seventy compounds were correlated with various molecular descriptors. We found that lipophilicity (modeled by the logarithm of the n-octanol/water partition coefficient, logP was the property that influenced most profoundly the potency of these compounds to inhibit lipid peroxidation in the biological medium studied. Additionally, the important contribution of the bond dissociation enthalpy of the phenolic O-H group, a shape index, the solvent-accessible surface area and the energy required to remove an electron from the highest occupied molecular orbital were also confirmed. Several QSAR equations were validated as potentially useful exploratory tools for identifying or designing novel phenolic antioxidants incorporating the structural backbone of 17β-estradiol to assist therapy development against oxidative stress-associated neurodegeneration.

  19. 结构脂的构效关系及酶法制备的研究进展%Research progress of structure-function relationship of structured lipids and enzymatic preparation

    Institute of Scientific and Technical Information of China (English)

    刘宁; 汪勇; 赵强忠; 赵谋明

    2012-01-01

    结构脂具有天然油脂的风味和物理特性,由于对人体具有特殊的生理功能和营养价值而倍受关注。本文基于结构脂的构效关系,对脂肪酶催化分子设计制备结构脂的研究现状进行了综述,系统介绍了人乳替代品、类可可脂、甘油二酯和单甘酯等热门结构脂的研究进展。%The structured lipids,which have similar flavor and physical characteristics as natural lipids,are attracting interestings due to their special physiological functions and nutritional values.Based on the relationship between structure and function,the applications of lipase-catalyzed molecular design on the preparation of structured lipids were summarized,especially certain types of structured lipids,such as human milk fat substitute,cocoa butter,diacylglycerols,monoacylglycerols,and so on.

  20. Lipid somersaults

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Menon, Anant K.

    2016-01-01

    Membrane lipids diffuse rapidly in the plane of the membrane but their ability to flip spontaneously across a membrane bilayer is hampered by a significant energy barrier. Thus spontaneous flip-flop of polar lipids across membranes is very slow, even though it must occur rapidly to support divers...

  1. Structure formation of lipid membranes: Membrane self-assembly and vesicle opening-up to octopus-like micelles

    Science.gov (United States)

    Noguchi, Hiroshi

    2013-02-01

    We briefly review our recent studies on self-assembly and vesicle rupture of lipid membranes using coarse-grained molecular simulations. For single component membranes, lipid molecules self-assemble from random gas states to vesicles via disk-shaped clusters. Clusters aggregate into larger clusters, and subsequently the large disks close into vesicles. The size of vesicles are determined by kinetics than by thermodynamics. When a vesicle composed of lipid and detergent types of molecules is ruptured, a disk-shaped micelle called bicelle can be formed. When both surfactants have negligibly low critical micelle concentration, it is found that bicelles connected with worm-like micelles are also formed depending on the surfactant ratio and spontaneous curvature of the membrane monolayer.

  2. Mass Spectrometry Methodology in Lipid Analysis

    OpenAIRE

    Lin Li; Juanjuan Han; Zhenpeng Wang; Jian'an Liu; Jinchao Wei; Shaoxiang Xiong; Zhenwen Zhao

    2014-01-01

    Lipidomics is an emerging field, where the structures, functions and dynamic changes of lipids in cells, tissues or body fluids are investigated. Due to the vital roles of lipids in human physiological and pathological processes, lipidomics is attracting more and more attentions. However, because of the diversity and complexity of lipids, lipid analysis is still full of challenges. The recent development of methods for lipid extraction and analysis and the combination with bioinformatics tech...

  3. Stability of lipid excipients in solid lipid nanoparticles.

    Science.gov (United States)

    Radomska-Soukharev, Anna

    2007-07-10

    The paper is devoted to the investigation of chemical stability of lipids used as excipients in the production of Solid Lipid Nanoparticles (SLN). Different lipids and amounts of surfactants were considered. Most of the formulations were produced using identical binary surfactant mixtures and concentrations to analyze the effect of the chemical nature of the lipids on their stability in SLN. In some formulations, surfactants were exchanged or their concentration was increased to assess the contribution of surfactants on stability of lipids particles. Solid Lipid Nanoparticles were characterized by photon correlation spectroscopy, laser diffractometry, zeta potential determination and differential scanning calorimetry. Potential effects of lipid crystallinity and modifications were assessed. A gas chromatography (GC) analysis in combination with a method for lipid extraction from aqueous SLN dispersions was used to investigate the chemical stability of the lipid excipients forming the particle matrix. All formulations were produced by the hot homogenization technique. The production process of SLN itself did not affect the chemical stability of lipid excipient forming the particle matrix. The formulations where lipids consisted of trigylicerides showed a negligible decomposition of the structure during incubation at 25 degrees C. Dynasan 118 showed the highest chemical stability (loss<4%) within two years.

  4. General aspects of peptide selectivity towards lipid bilayers and cell membranes studied by variation of the structural parameters of amphipathic helical model peptides.

    Science.gov (United States)

    Dathe, Margitta; Meyer, Jana; Beyermann, Michael; Maul, Björn; Hoischen, Christian; Bienert, Michael

    2002-02-01

    Model compounds of modified hydrophobicity (Eta), hydrophobic moment (mu) and angle subtended by charged residues (Phi) were synthesized to define the general roles of structural motifs of cationic helical peptides for membrane activity and selectivity. The peptide sets were based on a highly hydrophobic, non-selective KLA model peptide with high antimicrobial and hemolytic activity. Variation of the investigated parameters was found to be a suitable method for modifying peptide selectivity towards either neutral or highly negatively charged lipid bilayers. Eta and mu influenced selectivity preferentially via modification of activity on 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) bilayers, while the size of the polar/hydrophobic angle affected the activity against 1-palmitoyl-2-oleoylphosphatidyl-DL-glycerol (POPG). The influence of the parameters on the activity determining step was modest in both lipid systems and the activity profiles were the result of the parameters' influence on the second less pronounced permeabilization step. Thus, the activity towards POPC vesicles was determined by the high permeabilizing efficiency, however, changes in the structural parameters preferentially influenced the relatively moderate affinity. In contrast, intensive peptide accumulation via electrostatic interactions was sufficient for the destabilization of highly negatively charged POPG lipid membranes, but changes in the activity profile, as revealed by the modification of Phi, seem to be preferentially caused by variation of the low permeabilizing efficiency. The parameters proved very effective also in modifying antimicrobial and hemolytic activity. However, their influence on cell selectivity was limited. A threshold value of hydrophobicity seems to exist which restricted the activity modifying potential of mu and Phi on both lipid bilayers and cell membranes.

  5. Dietary rosemary oil alleviates heat stress-induced structural and functional damage through lipid peroxidation in the testes of growing Japanese quail.

    Science.gov (United States)

    Türk, Gaffari; Çeribaşı, Ali O; Şimşek, Ülkü G; Çeribaşı, Songül; Güvenç, Mehmet; Özer Kaya, Şeyma; Çiftçi, Mehmet; Sönmez, Mustafa; Yüce, Abdurrauf; Bayrakdar, Ali; Yaman, Mine; Tonbak, Fadime

    2016-01-01

    Supplementation of natural antioxidants to diets of male poultry has been reported to be effective in reducing or completely eliminating heat stress (HS)-induced reproductive failures. In this study, the aim is to investigate whether rosemary oil (RO) has a protective effect on HS-induced damage in spermatozoa production, testicular histologic structures, apoptosis, and androgenic receptor (AR) through lipid peroxidation mechanisms in growing Japanese quail. Male chicks (n=90) at 15-days of age were assigned to two groups. The first group (n=45) was kept in a thermo-neutral (TN) room at 22°C for 24h/d. The second group (n=45) was kept in a room with a greater ambient temperature of 34°C for 8h/d (from 9:00 AM to 5:00 PM) and 22°C for 16h/d. Animals in each of these two groups were randomly assigned to three subgroups (RO groups: 0, 125, 250ppm), consisting of 15 chicks (six treatment groups in 2×3 factorial design). Each of subgroups was replicated three times with each replicate including five chicks. The HS treatment significantly reduced the testicular spermatogenic cell counts, amount of testicular Bcl-2 (anti-apoptotic marker) and amount of AR. In addition, it significantly increased testicular lipid peroxidation, Bax (apoptotic marker) immunopositive staining, and the Bax/Bcl-2 ratio in conjunction with some histopathologic damage. Dietary supplementation of RO to diets of quail where the HS treatment was imposed alleviated HS-induced almost all negative changes such as increased testicular lipid peroxidation, decreased numbers of spermatogenic cells, and decreased amounts of Bcl-2 and AR, increased ratio of Bax/Bcl-2 and some testicular histopathologic lesion. In conclusion, dietary supplementation of RO for growing male Japanese quail reared in HS environmental conditions alleviates the HS-induced structural and functional damage by providing a decrease in lipid peroxidation.

  6. Composition, structure and absorption of milk lipids: a source of energy, fat-soluble nutrients and bioactive molecules.

    Science.gov (United States)

    German, J Bruce; Dillard, Cora J

    2006-01-01

    Milkfat is a remarkable source of energy, fat-soluble nutrients and bioactive lipids for mammals. The composition and content of lipids in milkfat vary widely among mammalian species. Milkfat is not only a source of bioactive lipid components, it also serves as an important delivery medium for nutrients, including the fat-soluble vitamins. Bioactive lipids in milk include triacylglycerides, diacylglycerides, saturated and polyunsaturated fatty acids, and phospholipids. Beneficial activities of milk lipids include anticancer, antimicrobial, anti-inflammatory, and immunosuppression properties. The major mammalian milk that is consumed by humans as a food commodity is that from bovine whose milkfat composition is distinct due to their diet and the presence of a rumen. As a result of these factors bovine milkfat is lower in polyunsaturated fatty acids and higher in saturated fatty acids than human milk, and the consequences of these differences are still being researched. The physical properties of bovine milkfat that result from its composition including its plasticity, make it a highly desirable commodity (butter) and food ingredient. Among the 12 major milk fatty acids, only three (lauric, myristic, and palmitic) have been associated with raising total cholesterol levels in plasma, but their individual effects are variable-both towards raising low-density lipoproteins and raising the level of beneficial high-density lipoproteins. The cholesterol-modifying response of individuals to consuming saturated fats is also variable, and therefore the composition, functions and biological properties of milkfat will need to be re-evaluated as the food marketplace moves increasingly towards more personalized diets.

  7. Influence of biological media on the structure and behavior of ferrocene-containing cationic lipid/DNA complexes used for DNA delivery.

    Science.gov (United States)

    Golan, Sharon; Aytar, Burcu S; Muller, John P E; Kondo, Yukishige; Lynn, David M; Abbott, Nicholas L; Talmon, Yeshayahu

    2011-06-07

    Biological media affect the physicochemical properties of cationic lipid-DNA complexes (lipoplexes) and can influence their ability to transfect cells. To develop new lipids for efficient DNA delivery, the influence of serum-containing media on the structures and properties of the resulting lipoplexes must be understood. To date, however, a clear and general picture of how serum-containing media influences the structures of lipoplexes has not been established. Some studies suggest that serum can disintegrate lipoplexes formed using certain types of cationic lipids, resulting in the inhibition of transfection. Other studies have demonstrated that lipoplexes formulated from other lipids are stable in the presence of serum and are able to transfect cells efficiently. In this article, we describe the influence of serum-containing media on lipoplexes formed using the redox-active cationic lipid bis(n-ferrocenylundecyl)dimethylammonium bromide (BFDMA). This lipoplex system promotes markedly decreased levels of transgene expression in COS-7 cells as serum concentrations are increased from 0 to 2, 5, 10, and 50% (v/v). To understand the cause of this decrease in transfection efficiency, we used cryogenic transmission electron microscopy (cryo-TEM) and measurements of zeta potential to characterize lipoplexes in cell culture media supplemented with 0, 2, 5, 10, and 50% serum. Cryo-TEM revealed that in serum-free media BFDMA lipoplexes form onionlike, multilamellar nanostructures. However, the presence of serum in the media caused disassociation of the intact multilamellar lipoplexes. At low serum concentrations (2 and 5%), DNA threads appeared to separate from the complex, leaving the nanostructure of the lipoplexes disrupted. At higher serum concentration (10%), disassociation increased and bundles of multilamellae were discharged from the main multilamellar complex. In contrast, lipoplexes characterized in serum-free aqueous salt (Li(2)SO(4)) medium and in OptiMEM cell

  8. Solid-State Nuclear Magnetic Resonance Investigation of the Structural Topology and Lipid Interactions of a Viral Fusion Protein Chimera Containing the Fusion Peptide and Transmembrane Domain.

    Science.gov (United States)

    Yao, Hongwei; Lee, Myungwoon; Liao, Shu-Yu; Hong, Mei

    2016-12-13

    The fusion peptide (FP) and transmembrane domain (TMD) of viral fusion proteins play important roles during virus-cell membrane fusion, by inducing membrane curvature and transient dehydration. The structure of the water-soluble ectodomain of viral fusion proteins has been extensively studied crystallographically, but the structures of the FP and TMD bound to phospholipid membranes are not well understood. We recently investigated the conformations and lipid interactions of the separate FP and TMD peptides of parainfluenza virus 5 (PIV5) fusion protein F using solid-state nuclear magnetic resonance. These studies provide structural information about the two domains when they are spatially well separated in the fusion process. To investigate how these two domains are structured relative to each other in the postfusion state, when the ectodomain forms a six-helix bundle that is thought to force the FP and TMD together in the membrane, we have now expressed and purified a chimera of the FP and TMD, connected by a Gly-Lys linker, and measured the chemical shifts and interdomain contacts of the protein in several lipid membranes. The FP-TMD chimera exhibits α-helical chemical shifts in all the membranes examined and does not cause strong curvature of lamellar membranes or membranes with negative spontaneous curvature. These properties differ qualitatively from those of the separate peptides, indicating that the FP and TMD interact with each other in the lipid membrane. However, no (13)C-(13)C cross peaks are observed in two-dimensional correlation spectra, suggesting that the two helices are not tightly associated. These results suggest that the ectodomain six-helix bundle does not propagate into the membrane to the two hydrophobic termini. However, the loosely associated FP and TMD helices are found to generate significant negative Gaussian curvature to membranes that possess spontaneous positive curvature, consistent with the notion that the FP-TMD assembly may

  9. Fluorescent lipid probes : some properties and applications (a review)

    NARCIS (Netherlands)

    Maier, O; Oberle, [No Value; Hoekstra, D

    2002-01-01

    Odd as it may seem, experimental challenges in lipid research are often hampered by the simplicity of the lipid structure. Since, as in protein research. mutants or overexpression of lipids are not realistic, a considerable amount of lipid research relies on the use Of tagged lipid analogues. Howeve

  10. Fluorescent lipid probes : some properties and applications (a review)

    NARCIS (Netherlands)

    Maier, O; Oberle, [No Value; Hoekstra, D

    Odd as it may seem, experimental challenges in lipid research are often hampered by the simplicity of the lipid structure. Since, as in protein research. mutants or overexpression of lipids are not realistic, a considerable amount of lipid research relies on the use Of tagged lipid analogues.

  11. Structural characterization of the polar lipids of Clostridium novyi NT. Further evidence for a novel anaerobic biosynthetic pathway to plasmalogens.

    Science.gov (United States)

    Guan, Ziqiang; Johnston, Norah C; Aygun-Sunar, Semra; Daldal, Fevzi; Raetz, Christian R H; Goldfine, Howard

    2011-03-01

    A study of the polar lipids of Clostridium novyi NT has revealed the presence of phosphatidylethanolamine (PE) and cardiolipin as major phospholipids with smaller amounts of phosphatidylglycerol (PG), lysyl-PG and alanyl-PG. Other minor phospholipids included phosphatidic acid, CDP-diacylglycerol, phosphatidylserine (PS) and phosphatidylthreonine (PT). PE, PG and amino acyl PG were present in both the diacyl and alk-1'-enyl acyl (plasmalogen) forms and cardiolipin plasmalogens were found to contain one or two alk-1'-enyl chains. In contrast, the precursor lipids phosphatidic acid, CDP-diacylglycerol and PS were present almost exclusively as diacyl phospholipids. These findings are consistent with the hypothesis that plasmalogens are formed from diacylated phospholipids at a late stage of phospholipid formation in Clostridium species. This novel pathway contrasts with the route in animals in which a saturated ether bond is formed at an early stage of plasmalogen biosynthesis and the alk-1-enyl bond is formed by an aerobic mechanism.

  12. G protein-membrane interactions II: Effect of G protein-linked lipids on membrane structure and G protein-membrane interactions.

    Science.gov (United States)

    Casas, Jesús; Ibarguren, Maitane; Álvarez, Rafael; Terés, Silvia; Lladó, Victoria; Piotto, Stefano P; Concilio, Simona; Busquets, Xavier; López, David J; Escribá, Pablo V

    2017-09-01

    G proteins often bear myristoyl, palmitoyl and isoprenyl moieties, which favor their association with the membrane and their accumulation in G Protein Coupled Receptor-rich microdomains. These lipids influence the biophysical properties of membranes and thereby modulate G protein binding to bilayers. In this context, we showed here that geranylgeraniol, but neither myristate nor palmitate, increased the inverted hexagonal (HII) phase propensity of phosphatidylethanolamine-containing membranes. While myristate and palmitate preferentially associated with phosphatidylcholine membranes, geranylgeraniol favored nonlamellar-prone membranes. In addition, Gαi1 monomers had a higher affinity for lamellar phases, while Gβγ and Gαβγ showed a marked preference for nonlamellar prone membranes. Moreover, geranylgeraniol enhanced the binding of G protein dimers and trimers to phosphatidylethanolamine-containing membranes, yet it decreased that of monomers. By contrast, both myristate and palmitate increased the Gαi1 preference for lamellar membranes. Palmitoylation reinforced the binding of the monomer to PC membranes and myristoylation decreased its binding to PE-enriched bilayer. Finally, binding of dimers and trimers to lamellar-prone membranes was decreased by palmitate and myristate, but it was increased in nonlamellar-prone bilayers. These results demonstrate that co/post-translational G protein lipid modifications regulate the membrane lipid structure and that they influence the physico-chemical properties of membranes, which in part explains why G protein subunits sort to different plasma membrane domains. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Structural Characterization of the Polar Lipids of Clostridium novyi NT. Further Evidence for a Novel Anaerobic Biosynthetic Pathway to Plasmalogens

    OpenAIRE

    Guan, Ziqiang; Johnston, Norah C.; Aygun-Sunar, Semra; Daldal, Fevzi; Raetz, Christian R. H.; Goldfine, Howard

    2010-01-01

    A study of the polar lipids of Clostridium novyi NT has revealed the presence of phosphatidylethanolamine (PE) and cardiolipin as major phospholipids with smaller amounts of phosphatidylglycerol (PG), lysyl-PG and alanyl-PG. Other minor phospholipids included phosphatidic acid, CDP-diacylglycerol, phosphatidylserine (PS) and phosphatidylthreonine (PT). PE, PG and amino acyl PG were present in both the diacyl and alk-1’-enyl acyl (plasmalogen) forms and cardiolipin plasmalogens were found to c...

  14. Arrangement of Annexin A2 tetramer and its impact on the structure and diffusivity of supported lipid bilayers

    DEFF Research Database (Denmark)

    Fritz, K.; Fritz, G.; Windschiegl, Barbara

    2010-01-01

    . Based on our results we propose that Anx A2t binds in a side-by-side configuration, i.e., both Anx A2 monomers bind to the bilayer with the p11 dimer positioned on top. Furthermore, we observe a strong decrease of lipid mobility upon binding of Anx A2t to SLBs with varying POPS content. X...... implications for the biochemical mechanism of Anx A2t-induced endo- and exocytosis....

  15. Lipids and membrane lateral organization

    Directory of Open Access Journals (Sweden)

    Sandro eSonnino

    2010-11-01

    Full Text Available Shortly after the elucidation of the very basic structure and properties of cellular membranes, it became evident that cellular membranes are highly organized structures with multiple and multi-dimensional levels of order. Very early observations suggested that the lipid components of biological membranes might be active players in the creations of these levels of order. In the late 80’s, several different and diverse experimental pieces of evidence coalesced together giving rise to the lipid raft hypothesis. Lipid rafts became enormously (and, in the opinion of these authors, sometimes acritically popular, surprisingly not just within the lipidologist community (who is supposed to be naturally sensitive to the fascination of lipid rafts. Today, a PubMed search using the key word lipid rafts returned a list of 3767 papers, including 690 reviews (as a term of comparison, searching over the same time span for a very hot lipid-related key word, ceramide returned 6187 hits with 799 reviews, and a tremendous number of different cellular functions have been described as lipid raft-dependent. However, a clear consensus definition of lipid raft has been proposed only in recent times, and the basic properties, the ruling forces, and even the existence of lipid rafts in living cells have been recently matter of intense debate. The scenario that is gradually emerging from the controversies elicited by the lipid raft hypothesis emphasize multiple roles for membrane lipids in determining membrane order, that encompasses their tendency to phase separation but are clearly not limited to this. In this review, we would like to re-focus the attention of the readers on the importance of lipids in organizing the fine structure of cellular membranes.

  16. Edible arabinoxylan-based films. 1. Effects of lipid type on water vapor permeability, film structure, and other physical characteristics.

    Science.gov (United States)

    Péroval, Claudine; Debeaufort, Frédéric; Despré, Denis; Voilley, Andrée

    2002-07-01

    Arabinoxylans (AX) are natural fibers extracted from maize bran, an industrial byproduct. To promote this polymer as a food ingredient, development of edible coatings and films had been proposed. Indeed, composite arabinoxylan-based films were prepared by emulsifying a fat: palmitic acid, oleic acid, triolein, or a hydrogenated palm oil (OK35). Lipid effects on water vapor permeability (WVP), surface hydrophobicity (contact angles), lipid particle size, and mechanical properties were investigated. Results showed that OK35-AX emulsion films had the lowest WVP. Emulsified films presented a bimodal particle size distribution; however, the smallest particle mean diameter (0.54 microm) was observed in OK35-AX emulsion films. Contact angles of water comparable to those observed for LDPE films (>90 degrees ) are measured on the OK35-AX film surface. Finally, only triolein-AX emulsion films had elongation higher than films without lipid. These results suggest that OK35 enhances functional properties of AX-based films and should be retained for further research.

  17. Introduction to fatty acids and lipids.

    Science.gov (United States)

    Burdge, Graham C; Calder, Philip C

    2015-01-01

    The purpose of this article is to describe the structure, function and metabolism of fatty acids and lipids that are of particular importance in the context of parenteral nutrition. Lipids are a heterogeneous group of molecules that share the common property of hydrophobicity. Lipids range in structure from simple short hydrocarbon chains to more complex molecules, including triacylglycerols, phospholipids and sterols and their esters. Lipids within each class may differ structurally. Fatty acids are common components of complex lipids, and these differ according to chain length and the presence, number and position of double bonds in the hydrocarbon chain. Structural variation among complex lipids and among fatty acids gives rise to functional differences that result in different impacts upon metabolism and upon cell and tissue responses. Fatty acids and complex lipids exhibit a variety of structural variations that influence their metabolism and their functional effects.

  18. Probing Structural Dynamics and Topology of the KCNE1 Membrane Protein in Lipid Bilayers via Site-Directed Spin Labeling and Electron Paramagnetic Resonance Spectroscopy.

    Science.gov (United States)

    Sahu, Indra D; Craig, Andrew F; Dunagan, Megan M; Troxel, Kaylee R; Zhang, Rongfu; Meiberg, Andrew G; Harmon, Corrinne N; McCarrick, Robert M; Kroncke, Brett M; Sanders, Charles R; Lorigan, Gary A

    2015-10-20

    KCNE1 is a single transmembrane protein that modulates the function of voltage-gated potassium channels, including KCNQ1. Hereditary mutations in the genes encoding either protein can result in diseases such as congenital deafness, long QT syndrome, ventricular tachyarrhythmia, syncope, and sudden cardiac death. Despite the biological significance of KCNE1, the structure and dynamic properties of its physiologically relevant native membrane-bound state are not fully understood. In this study, the structural dynamics and topology of KCNE1 in bilayered lipid vesicles was investigated using site-directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) spectroscopy. A 53-residue nitroxide EPR scan of the KCNE1 protein sequence including all 27 residues of the transmembrane domain (45-71) and 26 residues of the N- and C-termini of KCNE1 in lipid bilayered vesicles was analyzed in terms of nitroxide side-chain motion. Continuous wave-EPR spectral line shape analysis indicated the nitroxide spin label side-chains located in the KCNE1 TMD are less mobile when compared to the extracellular region of KCNE1. The EPR data also revealed that the C-terminus of KCNE1 is more mobile when compared to the N-terminus. EPR power saturation experiments were performed on 41 sites including 18 residues previously proposed to reside in the transmembrane domain (TMD) and 23 residues of the N- and C-termini to determine the topology of KCNE1 with respect to the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) lipid bilayers. The results indicated that the transmembrane domain is indeed buried within the membrane, spanning the width of the lipid bilayer. Power saturation data also revealed that the extracellular region of KCNE1 is solvent-exposed with some of the portions partially or weakly interacting with the membrane surface. These results are consistent with the previously published solution NMR

  19. Mass Spectrometry Methodology in Lipid Analysis

    Directory of Open Access Journals (Sweden)

    Lin Li

    2014-06-01

    Full Text Available Lipidomics is an emerging field, where the structures, functions and dynamic changes of lipids in cells, tissues or body fluids are investigated. Due to the vital roles of lipids in human physiological and pathological processes, lipidomics is attracting more and more attentions. However, because of the diversity and complexity of lipids, lipid analysis is still full of challenges. The recent development of methods for lipid extraction and analysis and the combination with bioinformatics technology greatly push forward the study of lipidomics. Among them, mass spectrometry (MS is the most important technology for lipid analysis. In this review, the methodology based on MS for lipid analysis was introduced. It is believed that along with the rapid development of MS and its further applications to lipid analysis, more functional lipids will be identified as biomarkers and therapeutic targets and for the study of the mechanisms of disease.

  20. Uncovering the lipidic basis for the preparation of functional nicotinic acetylcholine receptor detergent complexes for structural studies.

    Science.gov (United States)

    Quesada, Orestes; González-Freire, Carol; Ferrer, María Carla; Colón-Sáez, José O; Fernández-García, Emily; Mercado, Juan; Dávila, Alejandro; Morales, Reginald; Lasalde-Dominicci, José A

    2016-09-19

    This study compares the lipid composition, including individual phospholipid molecular species of solubilized nAChR detergent complexes (nAChR-DCs) with those of the bulk lipids from their source, Torpedo californica (Tc) electric tissue. This lipidomic analysis revealed seventy-seven (77) phospholipid species in the Tc tissue. Analysis of affinity-purified nAChR-DCs prepared with C-12 to C-16 phospholipid analog detergents alkylphosphocholine (FC) and lysofoscholine (LFC) demonstrated that nAChR-DCs prepared with FC12, LFC14, and LFC16 contained >60 phospholipids/nAChR, which was more than twice of those prepared with FC14, FC16, and LFC12. Significantly, all the nAChR-DCs lacked ethanolamine and anionic phospholipids, contained only four cholesterol molecules, and a limited number of phospholipid molecular species per nAChR. Upon incorporation into oocytes, FC12 produce significant functionality, whereas LFC14 and LFC16 nAChR-DCs displayed an increased functionality as compared to the crude Tc membrane. All three nAChR-DCs displayed different degrees of alterations in macroscopic activation and desensitization kinetics.

  1. ' q-Titration' of long-chain and short-chain lipids differentiates between structured and mobile residues of membrane proteins studied in bicelles by solution NMR spectroscopy

    Science.gov (United States)

    Son, Woo Sung; Park, Sang Ho; Nothnagel, Henry J.; Lu, George J.; Wang, Yan; Zhang, Hua; Cook, Gabriel A.; Howell, Stanley C.; Opella, Stanley J.

    2012-01-01

    ' q-Titration' refers to the systematic comparison of signal intensities in solution NMR spectra of uniformly 15N labeled membrane proteins solubilized in micelles and isotropic bicelles as a function of the molar ratios ( q) of the long-chain lipids (typically DMPC) to short-chain lipids (typically DHPC). In general, as q increases, the protein resonances broaden and correspondingly have reduced intensities due to the overall slowing of protein reorientation. Since the protein backbone signals do not broaden uniformly, the differences in line widths (and intensities) enable the narrower (more intense) signals associated with mobile residues to be differentiated from the broader (less intense) signals associated with "structured" residues. For membrane proteins with between one and seven trans-membrane helices in isotropic bicelles, we have been able to find a value of q between 0.1 and 1.0 where only signals from mobile residues are observed in the spectra. The signals from the structured residues are broadened so much that they cannot be observed under standard solution NMR conditions. This q value corresponds to the ratio of DMPC:DHPC where the signals from the structured residues are "titrated out" of the spectrum. This q value is unique for each protein. In magnetically aligned bilayers ( q > 2.5) no signals are observed in solution NMR spectra of membrane proteins because the polypeptides are "immobilized" by their interactions with the phospholipid bilayers on the relevant NMR timescale (˜10 5 Hz). No signals are observed from proteins in liposomes (only long-chain lipids) either. We show that it is feasible to obtain complementary solution NMR and solid-state NMR spectra of the same membrane protein, where signals from the mobile residues are present in the solution NMR spectra, and signals from the structured residues are present in the solid-state NMR spectra. With assigned backbone amide resonances, these data are sufficient to describe major features

  2. Lipid Ion Channels

    CERN Document Server

    Heimburg, Thomas

    2010-01-01

    The interpretation electrical phenomena in biomembranes is usually based on the assumption that the experimentally found discrete ion conduction events are due to a particular class of proteins called ion channels while the lipid membrane is considered being an inert electrical insulator. The particular protein structure is thought to be related to ion specificity, specific recognition of drugs by receptors and to macroscopic phenomena as nerve pulse propagation. However, lipid membranes in their chain melting regime are known to be highly permeable to ions, water and small molecules, and are therefore not always inert. In voltage-clamp experiments one finds quantized conduction events through protein-free membranes in their melting regime similar to or even undistinguishable from those attributed to proteins. This constitutes a conceptual problem for the interpretation of electrophysiological data obtained from biological membrane preparations. Here, we review the experimental evidence for lipid ion channels...

  3. How Do Lipids Localize in Lewy Bodies?

    NARCIS (Netherlands)

    Chaudhary, Himanshu; Subramaniam, Vinod; Claessens, Mireille

    2014-01-01

    Lewy bodies are the pathological hallmark of Parkinson's disease (PD). While fibrillar α-synuclein (αS) is the main protein component of Lewy bodies, these structures also contain lipids. To elucidate the presence of lipids in Lewy bodies, we investigated the interaction of lipids with monomeric and

  4. Binding of oligoarginine to membrane lipids and heparan sulfate: structural and thermodynamic characterization of a cell-penetrating peptide.

    Science.gov (United States)

    Gonçalves, Elisabete; Kitas, Eric; Seelig, Joachim

    2005-02-22

    Cell-penetrating peptides (CPPs) comprise a group of arginine-rich oligopeptides that are able to deliver exogenous cargo into cells. A first step in the internalization of CPPs is their binding to the cell surface, a reaction likely to involve membrane phospholipids and/or heparan sulfate proteoglycans (HSPGs). The present work characterizes the interaction of R(9), one of the most efficient CPPs, with either heparan sulfate (HS) or lipid vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG). Isothermal titration calorimetry shows that R(9) binds to HS with high affinity. Assuming that HS has n independent and equivalent binding sites for R(9), we find an association constant of 3.1 x 10(6) M(-1) at 28 degrees C. At this temperature, the reaction enthalpy is DeltaH(degrees)pep = - 5.5 kcal/mol and approximately 7 R(9) molecules bind per HS chain, which is equivalent to approximately 0.95 cationic/anionic charge ratio. Delta decreases in magnitude upon an increase in temperature, and the reaction becomes entropy-driven at higher temperatures (>or=37 degrees C). The positive heat-capacity change entailed by this reaction (DeltaC(degrees)P = +167 cal mol(-1) K(-1)) indicates the loss of polar residues on R(9)-HS binding, suggesting that hydrophobic forces play no major role on binding. Calorimetric analysis of the interaction of R(9) with POPC/POPG (75:25) vesicles reveals an association constant of 8.2 x 10(4) M(-1) at 28 degrees C. Using a surface partition equilibrium model to correct for electrostatic effects, we find an intrinsic partition constant of approximately 900 M(-1), a value that is also confirmed by electrophoretic mobility measurements. This corresponds to an electrostatic contribution of approximately 33% to the total free energy of binding. Deuterium nuclear magnetic resonance (NMR) shows no change in the headgroup conformation of POPC and POPG, suggesting

  5. Mass Spectrometry for Profiling LOS and Lipid A Structures from Whole-Cell Lysates: Directly from a Few Bacterial Colonies or from Liquid Broth Cultures.

    Science.gov (United States)

    Kocsis, Béla; Kilár, Anikó; Péter, Szandra; Dörnyei, Ágnes; Sándor, Viktor; Kilár, Ferenc

    2017-01-01

    Lipopolysaccharides (LPSs, endotoxins) are components of the outer cell membrane of most Gram-negative bacteria and can play an important role in a number of diseases of bacteria, including Gram-negative sepsis. The hydrophilic carbohydrate part of LPSs consists of a core oligosaccharide (in the case of an R-type LPS or lipooligosaccharide, LOS) linked to an O-polysaccharide chain (in the case of an S-type LPS), which is responsible for O-specific immunogenicity. The hydrophobic lipid A anchor is composed of a phosphorylated diglucosamine backbone to which varying numbers of ester- and amide-linked fatty acids are attached and this part of the LPSs is associated with endotoxicity. The detailed chemical characterization of endotoxins requires long-lasting large-scale isolation procedures, by which high-purity LPSs can be obtained. However, when a large number of bacterial samples and their LPS content are to be compared prompt, small-scale isolation methods are used for the preparation of endotoxins directly from bacterial cell cultures. The purity of the endotoxins extracted by these methods may not be high, but it is sufficient for analysis.Here, we describe a fast and easy micromethod suitable for extracting small quantities of LOS and a slightly modified micromethod for the detection of the lipid A constituents of the LPSs from bacteria grown in different culture media and evaluate the structures with mass spectrometry. The cellular LOS and lipid A were obtained from crude isolates of heat-killed cells, which were then subjected to matrix-assisted laser desorption/ionization mass spectrometry analysis. The observed ions in the 10-colony samples were similar to those detected for purified samples. The total time for the sample preparation and the MS analysis is less than 3 h.

  6. Oxidative stability of structured lipids containing C18:0, C18:1, C18:2, C18:3 or CLA in sn 2-position - as bulk lipids and in milk drinks

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Nielsen, Nina Skall; Xu, Xuebing

    2004-01-01

    by enzymatic interesterification with caprylic acid. Oxidative stability was compared in the five lipids themselves and in milk drinks containing 5% of the different SL. During storage, samples were taken for chemical and physical analyses. Moreover, sensory assessments were performed on milk drinks....... The oxidative stability of our SL was very different when comparing (a) bulk lipids and milk drink and (b) the five different batches of each product. SL based on oleic acid was the most unstable as bulk lipid, while SL based on linoleic acid was the most unstable in milk drink. SL based on CLA was the second...

  7. Structure and phase transformations of DPPC lipid bilayers in the presence of nanoparticles: insights from coarse-grained molecular dynamics simulations.

    Science.gov (United States)

    Prates Ramalho, J P; Gkeka, P; Sarkisov, L

    2011-04-05

    In this article, we investigate fluid-gel transformations of a DPPC lipid bilayer in the presence of nanoparticles, using coarse-grained molecular dynamics. Two types of nanoparticles are considered, specifically a 3 nm hydrophobic nanoparticle located in the core of the bilayer and a 6 nm charged nanoparticle located at the interface between the bilayer and water phase. Both negatively and positively charged nanoparticles at the bilayer interface are investigated. We demonstrate that the presence of all types of nanoparticles induces disorder effects in the structure of the lipid bilayer. These effects are characterized using computer visualization of the gel phase in the presence of nanoparticles, radial distribution functions, and order parameters. The 3 nm hydrophobic nanoparticle immersed in the bilayer core and the positively charged nanoparticle at the bilayer surface have no effect on the temperature of the fluid-gel transformation, compared to the bulk case. Interestingly, a negatively charged hydrophobic nanoparticle located at the surface of the bilayer causes slight shift of the fluid-gel transformation to a lower temperature, compared to the bulk bilayer case.

  8. Lipid functionalized biopolymers: A review.

    Science.gov (United States)

    Qurat-Ul-Ain; Zia, Khalid Mahmood; Zia, Fatima; Ali, Muhammad; Rehman, Saima; Zuber, Mohammad

    2016-12-01

    Lipids are the main source of energy and widely used for various applications. In this review, the modification of lipids by using them in combination with other biomaterials like natural and synthetic polymers is elaborated. These new blends have characteristic features of both polymers and are characterized by different techniques (NMR, DSC, TGA, IR and Raman spectroscopy etc.) to understand their structure, properties and functional behavior. Lipids are hydrophobic, have anti-oxidant and anti-bacterial properties and thus impart hydrophobicity and flexibility to the polymers. While the polymers, on the other hand, make the lipids tougher. Properties of few polymers such as starch, polyethylene protein and chitosan that have brittleness, low combustion rate and hydrophobicity, are improved by incorporation of lipids ultimately increased their flexibility, combustion rate and hydrophobicity respectively. This review article is also focused on emerging fields for the applications of these composite materials. The most notable application of composite materials are in the field of paint industry.

  9. Determination of structural topology of a membrane protein in lipid bilayers using polarization optimized experiments (POE) for static and MAS solid state NMR spectroscopy.

    Science.gov (United States)

    Mote, Kaustubh R; Gopinath, T; Veglia, Gianluigi

    2013-10-01

    The low sensitivity inherent to both the static and magic angle spinning techniques of solid-state NMR (ssNMR) spectroscopy has thus far limited the routine application of multidimensional experiments to determine the structure of membrane proteins in lipid bilayers. Here, we demonstrate the advantage of using a recently developed class of experiments, polarization optimized experiments, for both static and MAS spectroscopy to achieve higher sensitivity and substantial time-savings for 2D and 3D experiments. We used sarcolipin, a single pass membrane protein, reconstituted in oriented bicelles (for oriented ssNMR) and multilamellar vesicles (for MAS ssNMR) as a benchmark. The restraints derived by these experiments are then combined into a hybrid energy function to allow simultaneous determination of structure and topology. The resulting structural ensemble converged to a helical conformation with a backbone RMSD ~0.44 Å, a tilt angle of 24° ± 1°, and an azimuthal angle of 55° ± 6°. This work represents a crucial first step toward obtaining high-resolution structures of large membrane proteins using combined multidimensional oriented solid-state NMR and magic angle spinning solid-state NMR.

  10. Determination of structural topology of a membrane protein in lipid bilayers using polarization optimized experiments (POE) for static and MAS solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mote, Kaustubh R. [University of Minnesota, Department of Chemistry (United States); Gopinath, T. [University of Minnesota, Department of Biochemistry, Molecular Biology and Biophysics (United States); Veglia, Gianluigi, E-mail: vegli001@umn.edu [University of Minnesota, Department of Chemistry (United States)

    2013-10-15

    The low sensitivity inherent to both the static and magic angle spinning techniques of solid-state NMR (ssNMR) spectroscopy has thus far limited the routine application of multidimensional experiments to determine the structure of membrane proteins in lipid bilayers. Here, we demonstrate the advantage of using a recently developed class of experiments, polarization optimized experiments, for both static and MAS spectroscopy to achieve higher sensitivity and substantial time-savings for 2D and 3D experiments. We used sarcolipin, a single pass membrane protein, reconstituted in oriented bicelles (for oriented ssNMR) and multilamellar vesicles (for MAS ssNMR) as a benchmark. The restraints derived by these experiments are then combined into a hybrid energy function to allow simultaneous determination of structure and topology. The resulting structural ensemble converged to a helical conformation with a backbone RMSD {approx}0.44 A, a tilt angle of 24 Degree-Sign {+-} 1 Degree-Sign , and an azimuthal angle of 55 Degree-Sign {+-} 6 Degree-Sign . This work represents a crucial first step toward obtaining high-resolution structures of large membrane proteins using combined multidimensional oriented solid-state NMR and magic angle spinning solid-state NMR.

  11. LIBP-Pred: web server for lipid binding proteins using structural network parameters; PDB mining of human cancer biomarkers and drug targets in parasites and bacteria.

    Science.gov (United States)

    González-Díaz, Humberto; Munteanu, Cristian R; Postelnicu, Lucian; Prado-Prado, Francisco; Gestal, Marcos; Pazos, Alejandro

    2012-03-01

    Lipid-Binding Proteins (LIBPs) or Fatty Acid-Binding Proteins (FABPs) play an important role in many diseases such as different types of cancer, kidney injury, atherosclerosis, diabetes, intestinal ischemia and parasitic infections. Thus, the computational methods that can predict LIBPs based on 3D structure parameters became a goal of major importance for drug-target discovery, vaccine design and biomarker selection. In addition, the Protein Data Bank (PDB) contains 3000+ protein 3D structures with unknown function. This list, as well as new experimental outcomes in proteomics research, is a very interesting source to discover relevant proteins, including LIBPs. However, to the best of our knowledge, there are no general models to predict new LIBPs based on 3D structures. We developed new Quantitative Structure-Activity Relationship (QSAR) models based on 3D electrostatic parameters of 1801 different proteins, including 801 LIBPs. We calculated these electrostatic parameters with the MARCH-INSIDE software and they correspond to the entire protein or to specific protein regions named core, inner, middle, and surface. We used these parameters as inputs to develop a simple Linear Discriminant Analysis (LDA) classifier to discriminate 3D structure of LIBPs from other proteins. We implemented this predictor in the web server named LIBP-Pred, freely available at , along with other important web servers of the Bio-AIMS portal. The users can carry out an automatic retrieval of protein structures from PDB or upload their custom protein structural models from their disk created with LOMETS server. We demonstrated the PDB mining option performing a predictive study of 2000+ proteins with unknown function. Interesting results regarding the discovery of new Cancer Biomarkers in humans or drug targets in parasites have been discussed here in this sense.

  12. Substrate-supported lipid nanotube arrays.

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, A. I.; Poluektov, O. G.; Chemistry; North Carolina State

    2003-07-16

    This Communication describes the self-assembly of phospholipids into lipid nanotubes inside nanoporous anodic aluminum oxide substrate. Orientations of the lipid molecules in such lipid nanoscale structures were verified by high-resolution spin labeling EPR at 95 GHz. The static order parameter of lipids in such nanotube arrays was determined from low-temperature EPR spectra and was found to be exceptionally high, S{sub static} {approx} 0.9. We propose that substrate-supported lipid nanotube arrays have potential for building robust biochips and biosensors in which rigid nanoporous substrates protect the bilayer surface from contamination. The total bilayer surface in the lipid nanotube arrays is much greater than that in the planar substrate-supported membranes. The lipid nanotube arrays seem to be suitable for developing patterned lipid deposition and could be potentially used for patterning of membrane-associated molecules.

  13. Lipid droplets, lipophagy, and beyond.

    Science.gov (United States)

    Wang, Chao-Wen

    2016-08-01

    Lipids are essential components for life. Their various structural and physical properties influence diverse cellular processes and, thereby, human health. Lipids are not genetically encoded but are synthesized and modified by complex metabolic pathways, supplying energy, membranes, signaling molecules, and hormones to affect growth, physiology, and response to environmental insults. Lipid homeostasis is crucial, such that excess fatty acids (FAs) can be harmful to cells. To prevent such lipotoxicity, cells convert excess FAs into neutral lipids for storage in organelles called lipid droplets (LDs). These organelles do not simply manage lipid storage and metabolism but also are involved in protein quality management, pathogenesis, immune responses, and, potentially, neurodegeneration. In recent years, a major trend in LD biology has centered around the physiology of lipid mobilization via lipophagy of fat stored within LDs. This review summarizes key findings in LD biology and lipophagy, offering novel insights into this rapidly growing field. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

  14. Roles of Lipids in Photosynthesis.

    Science.gov (United States)

    Kobayashi, Koichi; Endo, Kaichiro; Wada, Hajime

    2016-01-01

    Thylakoid membranes in cyanobacterial cells and chloroplasts of algae and higher plants are the sites of oxygenic photosynthesis. The lipid composition of the thylakoid membrane is unique and highly conserved among oxygenic photosynthetic organisms. Major lipids in thylakoid membranes are glycolipids, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol, and the phospholipid, phosphatidylglycerol. The identification of almost all genes involved in the biosynthesis of each lipid class over the past decade has allowed the generation and isolation of mutants of various photosynthetic organisms incapable of synthesizing specific lipids. Numerous studies using such mutants have revealed that these lipids play important roles not only in the formation of the lipid bilayers of thylakoid membranes but also in the folding and assembly of the protein subunits in photosynthetic complexes. In addition to the studies with the mutants, recent X-ray crystallography studies of photosynthetic complexes in thylakoid membranes have also provided critical information on the association of lipids with photosynthetic complexes and their activities. In this chapter, we summarize our current understanding about the structural and functional involvement of thylakoid lipids in oxygenic photosynthesis.

  15. 脂筏微区超分子聚集体结构的稳定性%Stabilities of Supramolecular Complex Structures in Lipid Rafts Microdomains

    Institute of Scientific and Technical Information of China (English)

    孙润广; 张静; 郝长春; 陈莹莹; 杨谦

    2011-01-01

    The dynamic and stability characteristics of lipid raft microdomains dominate the functions of cell membranes. The flask-shaped caveolae, spherical and ellipsoidal structure of lipid rafts extracted from animal cells have been observed. The results of simulated experiments showed that the films of SM/Chol/DOPC took on obvious liquid ordered and liquid disordered coexisted phase. It could be induced to rearrangement by DOPE and ceramide on SM/Chol phase. In the mixed monolayers, the excess molecular area and excess Gibbs free energy determines the molecular interactions and stability respectively. The biological significance and the relationship between structure and function lipid rafts were explored on super-molecular level by combining extraction from cells in vivo and simulated in vitro method. This project conduction can provide theoretical evidence and experimental support for studying biomembrane.%脂筏微区结构的动态特征与稳定性决定着细胞膜的功能.脂筏在体分离形态观测呈现出烧瓶状凹陷、球状及椭球状结构.体外模拟实验表明,鞘磷脂( SM)/胆固醇(Chol )/1,2-二油酸甘油-3-磷脂酰胆碱( DOPC)呈现出明显的液态有序相和液态无序相共存的相分离膜结构.1,2-二油酸甘油-3-磷脂酰乙醇胺(DOPE)和神经酰胺(Ceramide)促使SM/Chol液态有序相发生重排.单层膜分析表明过量分子面积决定分子间的相互作用,过量吉布斯自由能决定膜的稳定性.通过动物细胞提取脂筏与体外模拟脂筏相结合的方法,从超分子水平阐述了脂筏微区结构与功能的生物学意义,为生物膜的研究提供了理论依据和实验支持.

  16. The effect of low calorie structured lipid palm mid fraction, virgin coconut oil and canola oil blend on rats body weight and plasma profile

    Science.gov (United States)

    Bakar, Aftar Mizan Abu; Ayob, Mohd Khan; Maskat, Mohamad Yusof

    2016-11-01

    This study was carried out to evaluate the effect of low calorie cocoa butter substitutes, the structured lipids (SLs) on rats' body weight and plasma lipid levels. The SLs were developed from a ternary blending of palm mid fraction (PMF), virgin coconut oil (VCO) and canola oil (CO). The optimized blends were then underwent enzymatic acidolysisusing sn-1,3-specific lipase. This process produced A12, a SL which hasa solid fat content almost comparable to cocoa butter but has low calories. Therefore, it has a high potential to be used for cocoa butter substitute with great nutritional values. Fourty two Sprague Dawley rats were divided into 6 groups and were force feed for a period of 2 months (56 days) and the group were Control 1(rodent chow), Control 2(cocoa butter), Control 3(PMF:VCO:CO 90:5:5 - S3 blend), High doseSL (A12:C8+S3), Medium dose SL (A12:C8+S3) and Low dose SL (A12:C8+S3). The body weight of each rat was recorded once daily. The plasma profile of treated and control rats, which comprised of total cholesterol, HDL cholesterol, LDL cholesterol and triglyceride was measured on day 0 (baseline) and day 56 (post-treatment). Low calorie structured lipid (SL) was synthesized through acidolysis reaction using sn 1-3-specific lipase of ThermomycesLanuginos (TLIM) among 25 samples with optimum parameter obtained from the RSM. Blood samples for plasma separation were collected using cardiac puncture and requiring anesthesia via tail vein(Anesthetics for rats: Ketamine/Xylazine) for day 0 and day 56. Results of the study showed that rats in group 1 and group 2 has gained weight by 1.66 g and 4.75 g respectively and showed significant difference (plipid revealed that the total blood cholesterol content of rats fed with either low dosage (1.39 ± 0.08 mmol/L), medium dosage (1.40 ± 0.08 mmol/L) or high dosage (1.42 ± 0.07 mmol/L) of SLs contains C8:0 for 56 days was significantly lower (p0.05) between G3 on day 0 and 56 days for total cholesterol. Meanwhile

  17. Immobilization, Regiospecificity Characterization and Application of Aspergillus oryzae Lipase in the Enzymatic Synthesis of the Structured Lipid 1,3-Dioleoyl-2-Palmitoylglycerol.

    Directory of Open Access Journals (Sweden)

    Haiying Cai

    Full Text Available The enzymatic synthesis of 1,3-dioleoyl-2-palmitoylglycerol (OPO, one of the main components of human milk fats, has been hindered by the relatively high cost of sn-1,3-specific lipases and the deficiency in biocatalyst stability. The sn-1,3-specific lipase from Aspergillus oryzae (AOL is highly and efficiently immobilized with the polystyrene-based hydrophobic resin D3520, with a significant 49.54-fold increase in specific lipase activity compared with the AOL powder in catalyzing the synthesis of OPO through the acidolysis between palm stearin and oleic acid (OA. The optimal immobilization conditions were investigated, including time course, initial protein concentration and solution pH. The sn-1,3 specificity of lipases under different immobilization conditions was evaluated and identified as positively associated with the lipase activity, and the pH of the immobilization solution influenced the regiospecificity and synthetic activity of these lipases. Immobilized AOL D3520, as the biocatalyst, was used for the enzymatic synthesis of the structured lipid OPO through the acidolysis between palm stearin and OA. The following conditions were optimized for the synthesis of structured lipid OPO: 65 °C temperature; 1:8 substrate molar ratio between palm stearin and OA; 8% (w/w enzyme load; 3.5% water content of the immobilized lipase; and 1 h reaction time. Under these conditions, highly efficient C52 production (45.65% was achieved, with a tripalmitin content of 2.75% and a sn-2 palmitic acid (PA proportion of 55.08% in the system.

  18. Progress in detection and structural characterization of glycosphingolipids in crude lipid extracts by enzymatic phospholipid disintegration combined with thin-layer chromatography immunodetection and IR-MALDI mass spectrometry.

    Science.gov (United States)

    Kouzel, Ivan U; Pirkl, Alexander; Pohlentz, Gottfried; Soltwisch, Jens; Dreisewerd, Klaus; Karch, Helge; Müthing, Johannes

    2014-01-21

    In order to proceed in detection and structural analysis of glycosphingolipids (GSLs) in crude lipid extracts, which still remains a challenge in glycosphingolipidomics, we developed a strategy to structurally characterize neutral GSLs in total lipid extracts prepared from in vitro propagated human monocytic THP-1 cells, which were used as a model cell line. The procedure divides into (1) extraction of total lipids from cellular material, (2) enzymatical disintegration of phospholipids by treatment of the crude lipid extract with phospholipase C, (3) subsequent multiple thin-layer chromatography (TLC) overlay detection of individual GSLs with a mixture of various anti-GSL antibodies, and (4) structural analysis of immunostained GSLs directly on the TLC plate using infrared matrix-assisted laser desorption/ionization orthogonal time-of-flight mass spectrometry (IR-MALDI-o-TOF MS) in combination with collision-induced dissociation (CID). Whereas GSLs were mostly undetectable in untreated crude lipid extracts, pretreatment with phospholipase C resulted in clear-cut mass spectra. MS(1) and MS(2) analysis gave similar results when compared to those obtained with a highly purified neutral GSL preparation of THP-1 cells, which served as a control. We could demonstrate in this study the feasibility of simultaneous multiple immunodetection of individual neutral GSLs in one and the same TLC run and their structural characterization in crude lipid extracts after phospholipase C treatment, thereby avoiding laborious and long-lasting sample purification. This powerful combinatorial technique allows for efficient structural characterization of GSLs in small tissue samples and takes a step forward in the emerging field of glycosphingolipidomics.

  19. Stratum corneum barrier lipids in cholesteatoma

    DEFF Research Database (Denmark)

    Svane-Knudsen, V; Halkier-Sørensen, L; Rasmussen, G;

    2000-01-01

    Specimens from primary cholesteatomas were examined under the electron microscope using a lipid-retaining method that is best suited for intracellular lipids and a method that is best for intercellular lipids. In the stratum granulosum of the squamous epithelium, a large number of Odland bodies...... emerged. When the corneocyte reaches the transitional stage to the stratum corneum, the Odland bodies accumulate near the cell membrane and discharge their contents of lipid and enzymes. The lipids are reorganized into multiple long sheets of lamellar structures that embrace the keratinized corneocytes......, as seen in the formation and maintenance of the cutaneous permeability barrier. In this study we draw the attention to the facts that the cholesteatoma epithelium is capable of producing not only cholesterol, but also several lipids, and that the lipid molecules are organized in multilamellar structures...

  20. Stratum Corneum Barrier Lipids in Cholesteatoma

    DEFF Research Database (Denmark)

    Svane-Knudsen, V; Halkier-Sørensen, L; Rasmussen, G

    2000-01-01

    emerged. When the corneocyte reaches the transitional stage to the stratum corneum, the Odland bodies accumulate near the cell membrane and discharge their contents of lipid and enzymes. The lipids are reorganized into multiple long sheets of lamellar structures that embrace the keratinized corneocytes......Specimens from primary cholesteatomas were examined under the electron microscope using a lipid-retaining method that is best suited for intracellular lipids and a method that is best for intercellular lipids. In the stratum granulosum of the squamous epithelium, a large number of Odland bodies......, as seen in the formation and maintenance of the cutaneous permeability barrier. In this study we draw the attention to the facts that the cholesteatoma epithelium is capable of producing not only cholesterol, but also several lipids, and that the lipid molecules are organized in multilamellar structures...

  1. Effect of freeze-drying, cryoprotectants and storage conditions on the stability of secondary structure of insulin-loaded solid lipid nanoparticles.

    Science.gov (United States)

    Soares, Sandra; Fonte, Pedro; Costa, Ana; Andrade, José; Seabra, Vítor; Ferreira, Domingos; Reis, Salette; Sarmento, Bruno

    2013-11-18

    This study aims to monitor the secondary structure behaviour of insulin when it is encapsulated into solid lipid nanoparticles (SLN), under the influence of several critical processing parameters. Insulin was used as a therapeutic protein model. Physicochemical properties of insulin-loaded SLN (Ins-SLN) were assessed, with special focus on the insulin secondary structure after its encapsulation into SLN and after freeze-drying using different cryoprotectants (glucose, fructose and sorbitol). Additionally, a 6-month stability study was performed to evaluate the maintenance of insulin secondary structure over time at different storage conditions (4 °C/60% RH, 25 °C/60% RH, 40 °C/75% RH). Ins-SLN were successfully produced with a mean and narrow particle size around 400 nm, zeta potential around -13 mV, an insulin association efficiency of 84%. Physical-chemical properties of SLN were maintained after freeze-drying. FTIR results showed that encapsulated insulin maintained a native-like structure in a degree of similarity around 92% after production, and 84% after freeze-drying. After 6 months, freeze-dried Ins-SLN without cryoprotectant stored at 40 °C/75% RH presented the same degree of structure preservation and morphology. Results revealed that insulin structure can be significantly protected by SLN matrix itself, without a cryoprotectant agent, even using a non-optimized freeze-drying process, and under the harsher storage conditions. Multivariable experimental settled the process parameters to fit with the desired product quality attributes regarding protein and nanoparticle stability.

  2. Fluorescopic evaluation of protein-lipid relations in cellular signalling.

    NARCIS (Netherlands)

    Pap, E.H.W.

    1994-01-01

    IntroductionCellular communication is partly mediated through the modulation of protein activity, structure and dynamics by lipids. In contrast to the biochemical aspects of lipid signalling, relatively little is known about the physical properties of the "signal" lipids (lipids involved in cellular

  3. Electronic polymers in lipid membranes.

    Science.gov (United States)

    Johansson, Patrik K; Jullesson, David; Elfwing, Anders; Liin, Sara I; Musumeci, Chiara; Zeglio, Erica; Elinder, Fredrik; Solin, Niclas; Inganäs, Olle

    2015-06-10

    Electrical interfaces between biological cells and man-made electrical devices exist in many forms, but it remains a challenge to bridge the different mechanical and chemical environments of electronic conductors (metals, semiconductors) and biosystems. Here we demonstrate soft electrical interfaces, by integrating the metallic polymer PEDOT-S into lipid membranes. By preparing complexes between alkyl-ammonium salts and PEDOT-S we were able to integrate PEDOT-S into both liposomes and in lipid bilayers on solid surfaces. This is a step towards efficient electronic conduction within lipid membranes. We also demonstrate that the PEDOT-S@alkyl-ammonium:lipid hybrid structures created in this work affect ion channels in the membrane of Xenopus oocytes, which shows the possibility to access and control cell membrane structures with conductive polyelectrolytes.

  4. Lipid dynamics at dendritic spines.

    Science.gov (United States)

    Dotti, Carlos Gerardo; Esteban, Jose Antonio; Ledesma, María Dolores

    2014-01-01

    Dynamic changes in the structure and composition of the membrane protrusions forming dendritic spines underlie memory and learning processes. In recent years a great effort has been made to characterize in detail the protein machinery that controls spine plasticity. However, we know much less about the involvement of lipids, despite being major membrane components and structure determinants. Moreover, protein complexes that regulate spine plasticity depend on specific interactions with membrane lipids for proper function and accurate intracellular signaling. In this review we gather information available on the lipid composition at dendritic spine membranes and on its dynamics. We pay particular attention to the influence that spine lipid dynamism has on glutamate receptors, which are key regulators of synaptic plasticity.

  5. Crystal Structure of Phosphatidylglycerophosphatase (PGPase), a Putative Membrane-Bound Lipid Phosphatase, Reveals a Novel Binuclear Metal Binding Site and Two Proton Wires

    Energy Technology Data Exchange (ETDEWEB)

    Kumaran,D.; Bonnano, J.; Burley, S.; Swaminathan, S.

    2006-01-01

    Phosphatidylglycerophosphatase (PGPase), an enzyme involved in lipid metabolism, catalyzes formation of phosphatidylglycerol from phosphatidylglycerophosphate. Phosphatidylglycerol is a multifunctional phospholipid, found in the biological membranes of many organisms. Here, we report the crystal structure of Listeria monocytogenes PGPase at 1.8 Angstroms resolution. PGPase, an all-helical molecule, forms a homotetramer. Each protomer contains an independent active site with two metal ions, Ca{sup 2+} and Mg{sup 2+}, forming a hetero-binuclear center located in a hydrophilic cavity near the surface of the molecule. The binuclear center, conserved ligands, metal-bound water molecules, and an Asp-His dyad form the active site. The catalytic mechanism of this enzyme is likely to proceed via binuclear metal activated nucleophilic water. The binuclear metal-binding active-site environment of this structure should provide insights into substrate binding and metal-dependent catalysis. A long channel with inter-linked linear water chains, termed 'proton wires', is observed at the tetramer interface. Comparison of similar water chain structures in photosynthetic reaction centers (RCs), Cytochrome f, gramicidin, and bacteriorhodopsin, suggests that PGPase may conduct protons via proton wires.

  6. Structure of a heterogeneous, glycosylated, lipid-bound, in vivo-grown protein crystal at atomic resolution from the viviparous cockroach Diploptera punctata

    Directory of Open Access Journals (Sweden)

    Sanchari Banerjee

    2016-07-01

    Full Text Available Macromolecular crystals for X-ray diffraction studies are typically grown in vitro from pure and homogeneous samples; however, there are examples of protein crystals that have been identified in vivo. Recent developments in micro-crystallography techniques and the advent of X-ray free-electron lasers have allowed the determination of several protein structures from crystals grown in cellulo. Here, an atomic resolution (1.2 Å crystal structure is reported of heterogeneous milk proteins grown inside a living organism in their functional niche. These in vivo-grown crystals were isolated from the midgut of an embryo within the only known viviparous cockroach, Diploptera punctata. The milk proteins crystallized in space group P1, and a structure was determined by anomalous dispersion from the native S atoms. The data revealed glycosylated proteins that adopt a lipocalin fold, bind lipids and organize to form a tightly packed crystalline lattice. A single crystal is estimated to contain more than three times the energy of an equivalent mass of dairy milk. This unique storage form of nourishment for developing embryos allows access to a constant supply of complete nutrients. Notably, the crystalline cockroach-milk proteins are highly heterogeneous with respect to amino-acid sequence, glycosylation and bound fatty-acid composition. These data present a unique example of protein heterogeneity within a single in vivo-grown crystal of a natural protein in its native environment at atomic resolution.

  7. Structure of a heterogeneous, glycosylated, lipid-bound, in vivo-grown protein crystal at atomic resolution from the viviparous cockroach Diploptera punctata.

    Science.gov (United States)

    Banerjee, Sanchari; Coussens, Nathan P; Gallat, François-Xavier; Sathyanarayanan, Nitish; Srikanth, Jandhyam; Yagi, Koichiro J; Gray, James S S; Tobe, Stephen S; Stay, Barbara; Chavas, Leonard M G; Ramaswamy, Subramanian

    2016-07-01

    Macromolecular crystals for X-ray diffraction studies are typically grown in vitro from pure and homogeneous samples; however, there are examples of protein crystals that have been identified in vivo. Recent developments in micro-crystallography techniques and the advent of X-ray free-electron lasers have allowed the determination of several protein structures from crystals grown in cellulo. Here, an atomic resolution (1.2 Å) crystal structure is reported of heterogeneous milk proteins grown inside a living organism in their functional niche. These in vivo-grown crystals were isolated from the midgut of an embryo within the only known viviparous cockroach, Diploptera punctata. The milk proteins crystallized in space group P1, and a structure was determined by anomalous dispersion from the native S atoms. The data revealed glycosylated proteins that adopt a lipocalin fold, bind lipids and organize to form a tightly packed crystalline lattice. A single crystal is estimated to contain more than three times the energy of an equivalent mass of dairy milk. This unique storage form of nourishment for developing embryos allows access to a constant supply of complete nutrients. Notably, the crystalline cockroach-milk proteins are highly heterogeneous with respect to amino-acid sequence, glycosylation and bound fatty-acid composition. These data present a unique example of protein heterogeneity within a single in vivo-grown crystal of a natural protein in its native environment at atomic resolution.

  8. The Crystal Structure of the Lipid II-degrading Bacteriocin Syringacin M Suggests Unexpected Evolutionary Relationships between Colicin M-like Bacteriocins

    Science.gov (United States)

    Grinter, Rhys; Roszak, Aleksander W.; Cogdell, Richard J.; Milner, Joel J.; Walker, Daniel

    2012-01-01

    Colicin-like bacteriocins show potential as next generation antibiotics with clinical and agricultural applications. Key to these potential applications is their high potency and species specificity that enables a single pathogenic species to be targeted with minimal disturbance of the wider microbial community. Here we present the structure and function of the colicin M-like bacteriocin, syringacin M from Pseudomonas syringae pv. tomato DC3000. Syringacin M kills susceptible cells through a highly specific phosphatase activity that targets lipid II, ultimately inhibiting peptidoglycan synthesis. Comparison of the structures of syringacin M and colicin M reveals that, in addition to the expected similarity between the homologous C-terminal catalytic domains, the receptor binding domains of these proteins, which share no discernible sequence homology, share a striking structural similarity. This indicates that the generation of the novel receptor binding and species specificities of these bacteriocins has been driven by diversifying selection rather than diversifying recombination as suggested previously. Additionally, the structure of syringacin M reveals the presence of an active site calcium ion that is coordinated by a conserved aspartic acid side chain and is essential for catalytic activity. We show that mutation of this residue to alanine inactivates syringacin M and that the metal ion is absent from the structure of the mutant protein. Consistent with the presence of Ca2+ in the active site, we show that syringacin M activity is supported by Ca2+, along with Mg2+ and Mn2+, and the protein is catalytically inactive in the absence of these ions. PMID:22995910

  9. Monoacyl phosphatidylcholine inhibits the formation of lipid multilamellar structures during in vitro lipolysis of self-emulsifying drug delivery systems

    DEFF Research Database (Denmark)

    Tran, Thuy; Siqueira, Scheyla D V S; Amenitsch, Heinz

    2016-01-01

    The colloidal structures formed during lipolysis of self-emulsifying drug delivery systems (SEDDS) might affect the solubilisation and possibly the absorption of drugs. The aim of the current study is to elucidate the structures formed during the in vitro lipolysis of four SEDDS containing medium....... However, SEDDS containing 20-30% w/w MAPC did not form MLS during the lipolysis. The cryo-TEM and DLS studies showed that MAPC-free SEDDS formed coarse emulsions while MAPC-containing SEDDS formed nanoemulsions during the dispersion in digestion medium. From the first minute and during the entire...

  10. Isolation and analysis of membrane lipids and lipid rafts in common carp (Cyprinus carpio L.).

    Science.gov (United States)

    Brogden, Graham; Propsting, Marcus; Adamek, Mikolaj; Naim, Hassan Y; Steinhagen, Dieter

    2014-03-01

    Cell membranes act as an interface between the interior of the cell and the exterior environment and facilitate a range of essential functions including cell signalling, cell structure, nutrient uptake and protection. It is composed of a lipid bilayer with integrated proteins, and the inner leaflet of the lipid bilayer comprises of liquid ordered (Lo) and liquid disordered (Ld) domains. Lo microdomains, also named as lipid rafts are enriched in cholesterol, sphingomyelin and certain types of proteins, which facilitate cell signalling and nutrient uptake. Lipid rafts have been extensively researched in mammals and the presence of functional lipid rafts was recently demonstrated in goldfish, but there is currently very little knowledge about their composition and function in fish. Therefore a protocol was established for the analysis of lipid rafts and membranous lipids in common carp (Cyprinus carpio L.) tissues. Twelve lipids were identified and analysed in the Ld domain of the membrane with the most predominant lipids found in all tissues being; triglycerides, cholesterol, phosphoethanolamine and phosphatidylcholine. Four lipids were identified in lipid rafts in all tissues analysed, triglycerides (33-62%) always found in the highest concentration followed by cholesterol (24-32%), phosphatidylcholine and sphingomyelin. Isolation of lipid rafts was confirmed by identifying the presence of the lipid raft associated protein flotillin, present at higher concentrations in the detergent resistant fraction. The data provided here build a lipid library of important carp tissues as a baseline for further studies into virus entry, protein trafficking or environmental stress analysis.

  11. Effect of structured lipids based on fish oil on the growth and fatty acid composition in Rainbow Trout (Oncorhynchus mykiss)

    DEFF Research Database (Denmark)

    Nielsen, Nina Skall; Gøttsche, Jesper; Holm, Jørgen

    2005-01-01

    The aim of the study was to investigate whether it was possible a) to increase the relative incorporation of n - 3 very long chain polyunsaturated fatty acids (VLCPUFA) in a low VLCPUFA diet by feeding trout structured triacylglycerols and b) to reduce fat accumulation by feeding trout a diet con...

  12. A study on the structural features of SELK, an over-expressed protein in hepatocellular carcinoma, by molecular dynamics simulations in a lipid-water system.

    Science.gov (United States)

    Polo, Andrea; Guariniello, Stefano; Colonna, Giovanni; Ciliberto, Gennaro; Costantini, Susan

    2016-10-20

    Human SELK is a small trans-membrane selenoprotein characterized by a single trans-membrane helix, while the N-terminal region protrudes into the lumen and the long C-terminal domain into the cytoplasm. SELK is over-expressed in some cancers, like hepatocellular carcinoma; however its precise role in cancer development is presently unknown. SELK is involved in promoting the calcium flux, catalyzing palmitoylation reactions and protein degradation in the endoplasmic reticulum (ER). Therefore, this protein should bind many different proteins like p97/VCP in the supramolecular complex involved in the ER degradation pathway. To study the structural features of SELK in the membrane, we have modeled the protein and then subjected it to molecular dynamics simulations in a lipid-water system. The model shows a N-terminal domain with three β-strands and a short helix, a well-defined trans-membrane helix and a C-terminal domain that lacks a persistent secondary structure and contains long disordered regions. The trajectory analysis during the simulation evidences that: (i) the N-terminal region explores a limited conformational space and is stabilized by intra-peptide H-bonds as well with membrane lipids and water, (ii) the trans-membrane helix was found to be quite stable and (iii) the disordered C-terminal region is stabilized by H-bonds with clustered water molecules as well as by rapidly interchanging intra-peptidic H-bonds, with a structural tendency to compact around the four HUB residues found for this domain. Moreover, N-terminal and C-terminal clusters are distributed differently in the conformational space suggesting that their dynamics are coupled complicatedly through the membrane. Further analyses have shown that the N-terminal has a tendency to pivot around the insertion with the TM-helix through the fluctuations of the three β-strands, which, in turn, show features similar to WW-domains. These results will be useful to study the SELK, SELS and VCP complex

  13. Hybrid lipid-based nanostructures

    Science.gov (United States)

    Dayani, Yasaman

    Biological membranes serve several important roles, such as structural support of cells and organelles, regulation of ionic and molecular transport, barriers to non-mediated transport, contact between cells within tissues, and accommodation of membrane proteins. Membrane proteins and other vital biomolecules incorporated into the membrane need a lipid membrane to function. Due to importance of lipid bilayers and their vital function in governing many processes in the cell, the development of various models as artificial lipid membranes that can mimic cell membranes has become a subject of great interest. Using different models of artificial lipid membranes, such as liposomes, planar lipid bilayers and supported or tethered lipid bilayers, we are able to study many biophysical processes in biological membranes. The ability of different molecules to interact with and change the structure of lipid membranes can be also investigated in artificial lipid membranes. An important application of lipid bilayer-containing interfaces is characterization of novel membrane proteins for high throughput drug screening studies to investigate receptor-drug interactions and develop biosensor systems. Membrane proteins need a lipid bilayer environment to preserve their stability and functionality. Fabrication of materials that can interact with biomolecules like proteins necessitates the use of lipid bilayers as a mimic of cell membranes. The objective of this research is to develop novel hybrid lipid-based nanostructures mimicking biological membranes. Toward this aim, two hybrid biocompatible structures are introduced: lipid bilayer-coated multi-walled carbon nanotubes (MWCNTs) and hydrogel-anchored liposomes with double-stranded DNA anchors. These structures have potential applications in biosensing, drug targeting, drug delivery, and biophysical studies of cell membranes. In the first developed nanostructure, lipid molecules are covalently attached to the surfaces of MWCNTs, and

  14. Lipid composition of human meibum

    Directory of Open Access Journals (Sweden)

    R. Schnetler

    2013-12-01

    Full Text Available The structure and function of meibomian gland lipids in the tear film are highly complex. Evidence shows that the precorneal tear film consists of discrete layers: the inner mucin layer, the middle aqueous layer and the outer lipid layer. In this review we focus on the outer, biphasic lipid layer of the tear film which consists of a ‘thick’ outer, non-polar layer  and a ‘thin’ inner, polar layer. We discuss the main composition of the polar and non-polar lipids within meibum (wax esters, cholesteryl esters, mono-, di- and tri-acylglycerols, ceramides, phospholipids  et cetera. We address the composition of meibomian lipids in subjects suffering from various ocular diseases in comparison with the composition in healthy individuals. Further analysis is needed to determine whether a correlation exists between the etiology of various ocular diseases and the fluctuation on the lipids as well as to establish whether or not tear lipid analysis can be used as a diagnostic tool.

  15. Dietary structured lipids for post-weaning piglets: fat digestibility, nitrogen retention and fatty acid profiles of tissues

    DEFF Research Database (Denmark)

    Straarup, Ellen Marie; Danielsen, V.; Høy, Carl-Erik

    2006-01-01

    In four groups of post-weaning piglets the effects of triacylglycerol structure and fatty acid profiles of four dietary fats on apparent faecal nutrient digestibility, nitrogen retention and fatty acid profiles of platelet and erythrocyte membranes, liver, adipose tissue and skeletal muscle were...... to the third week in the groups R1 and R2. Fatty acid profiles in platelet and erythrocyte membranes and in tissues reflected the fatty acid profile of the dietary fat, except for medium-chain fatty acids, which were only found in low proportions, indicating that 10:0 was mainly used as an energy source....... examined. Dietary fats included as 10% (w/w) of the diets were two structured fats of rapeseed oil interesterified with tridecanoin (R1) or coconut oil (R2), respectively, one mixture of rapeseed oil and coconut oil (R3) and rapeseed oil as control (R4). Faeces and urine from piglets weaned at 28 days...

  16. Dietary structured lipids for post-weaning piglets: fat digestibility, nitrogen retention and fatty acid profiles of tissues

    DEFF Research Database (Denmark)

    Straarup, Ellen Marie; Danielsen, V.; Høy, Carl-Erik

    2006-01-01

    In four groups of post-weaning piglets the effects of triacylglycerol structure and fatty acid profiles of four dietary fats on apparent faecal nutrient digestibility, nitrogen retention and fatty acid profiles of platelet and erythrocyte membranes, liver, adipose tissue and skeletal muscle were...... interesterified fats or the physical mixtures (R1, R2 and R3) compared with rapeseed oil (R4). Apparent faecal nitrogen digestibility and retention were similar in all four groups in the three periods, but increased with time. Apparent faecal fat digestibilities were significantly improved from the first...... examined. Dietary fats included as 10% (w/w) of the diets were two structured fats of rapeseed oil interesterified with tridecanoin (R1) or coconut oil (R2), respectively, one mixture of rapeseed oil and coconut oil (R3) and rapeseed oil as control (R4). Faeces and urine from piglets weaned at 28 days...

  17. Lipid membranes on nanostructured silicon.

    Energy Technology Data Exchange (ETDEWEB)

    Slade, Andrea Lynn; Lopez, Gabriel P. (University of New Mexico, Albuquerque, NM); Ista, Linnea K. (University of New Mexico, Albuquerque, NM); O' Brien, Michael J. (University of New Mexico, Albuquerque, NM); Sasaki, Darryl Yoshio; Bisong, Paul (University of New Mexico, Albuquerque, NM); Zeineldin, Reema R. (University of New Mexico, Albuquerque, NM); Last, Julie A.; Brueck, Stephen R. J. (University of New Mexico, Albuquerque, NM)

    2004-12-01

    A unique composite nanoscale architecture that combines the self-organization and molecular dynamics of lipid membranes with a corrugated nanotextured silicon wafer was prepared and characterized with fluorescence microscopy and scanning probe microscopy. The goal of this project was to understand how such structures can be assembled for supported membrane research and how the interfacial interactions between the solid substrate and the soft, self-assembled material create unique physical and mechanical behavior through the confinement of phases in the membrane. The nanometer scale structure of the silicon wafer was produced through interference lithography followed by anisotropic wet etching. For the present study, a line pattern with 100 nm line widths, 200 nm depth and a pitch of 360 nm pitch was fabricated. Lipid membranes were successfully adsorbed on the structured silicon surface via membrane fusion techniques. The surface topology of the bilayer-Si structure was imaged using in situ tapping mode atomic force microscopy (AFM). The membrane was observed to drape over the silicon structure producing an undulated topology with amplitude of 40 nm that matched the 360 nm pitch of the silicon structure. Fluorescence recovery after photobleaching (FRAP) experiments found that on the microscale those same structures exhibit anisotropic lipid mobility that was coincident with the silicon substructure. The results showed that while the lipid membrane maintains much of its self-assembled structure in the composite architecture, the silicon substructure indeed influences the dynamics of the molecular motion within the membrane.

  18. Lipid signaling in plants

    NARCIS (Netherlands)

    Munnik, T.

    2010-01-01

    This book highlights the current status of plant lipid signaling. Written by leading researchers in the field, the chapters include detailed information on the measurement, regulation and function of phospholipases, lipid kinases, lipid phosphatases, inositolpolyphosphates, polyphosphoinositides, ph

  19. Lipid Metabolism Disorders

    Science.gov (United States)

    ... metabolic disorder, something goes wrong with this process. Lipid metabolism disorders, such as Gaucher disease and Tay-Sachs disease, involve lipids. Lipids are fats or fat-like substances. They ...

  20. Molecular restructuring of water and lipids upon the interaction of DNA with lipid monolayers.

    Science.gov (United States)

    Campen, R Kramer; Ngo, Thuy T M; Sovago, Maria; Ruysschaert, Jean-Marie; Bonn, Mischa

    2010-06-16

    Understanding the molecular mechanism of DNA/lipid interaction is critical in optimizing the use of lipid cofactors in gene therapy. Here, we address this question by employing label-free vibrational sum frequency (VSF) spectroscopy to study the interaction of DNA with lipid monolayers of the cationic lipids DPTAP(1,2-dipalmitoyl-3-trimethylammonium-propane) and diC14-amidine as well as the zwitterionic lipid DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) in the presence and absence of calcium. Our approach has the advantage both of allowing us to explicitly probe intermolecular interactions and of providing insight into the structure of water and lipids around DNA at the lipid interface. We find, by examination of the OD stretch of interfacial D(2)O, that water structure differs markedly between systems containing DNA adsorbed to cationic and those that contain DNA adsorbed to zwitterionic lipid monolayers (in the presence or absence of Ca(2+)). The spectral response of interfacial water in the cationic system is consistent with a highly structured, undercoordinated, structural 'type' of water. Further, by investigation of CH stretch modes of the diC14-amidine lipid tails, we demonstrate that the adsorption of DNA to this lipid leads to increased ordering of lipid tails.

  1. Distribution of medium-chain FA in different lipid classes after administration of specific structured TAG in rats

    DEFF Research Database (Denmark)

    Mu, Huiling; Høy, Carl-Erik

    2002-01-01

    -sn-glycerol (12:0/18:2/12:0). We conclude that the enterocyte has the ability to reacylate the MCFA into TAG and that the intestinal absorption of MCFA from STAG mainly occurs by resynthesis of TAG. Caprylic acid from STAG is not incorporated into phospholipids, whereas lauric acid from STAG can be incorporated......Structured TAG (STAG) containing medium-chain FA (MCFA) in the sn-1,3 positions and essential FA in the sn-2 position were synthesized by lipase-catalyzed acidolysis. In our previous studies we found that part of the MCFA from STAG could be absorbed in the small intestine; however, it was unclear...

  2. Association of structural variants of the gene of apolipoprotein B with coronary heart disease and serum lipid level

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, V.A.; Puzyrev, V.P.; Lemza, S.V. [Institute of Medical Genetics, Tomsk (Russian Federation); Karpov, R.S.; Fedorov, A.Yu. [Institute of Cardiology, Tomsk (Russian Federation)

    1995-07-01

    Xba I and EcoR I polymorphism of the apolipoprotein B (APOB) gene was studied by PCR. A significant increase in the frequency of allele X{sup +} and haplotype X{sup +}E{sup +} was demonstrated in patients with coronarographically documented coronary heart disease (CHD) over that of the general population. Association of allele E{sup {minus}} with increased levels of serum triglycerides was found. The results provide evidence about the contribution of structural variants of the APOB gene to determining CHD. 21 refs., 4 tabs.

  3. Effects of Two Types of Melatonin-Loaded Nanocapsules with Distinct Supramolecular Structures: Polymeric (NC and Lipid-Core Nanocapsules (LNC on Bovine Embryo Culture Model.

    Directory of Open Access Journals (Sweden)

    Eliza Rossi Komninou

    Full Text Available Melatonin has been used as a supplement in culture medium to improve the efficiency of in vitro produced mammalian embryos. Through its ability to scavenge toxic oxygen derivatives and regulate cellular mRNA levels for antioxidant enzymes, this molecule has been shown to play a protective role against damage by free radicals, to which in vitro cultured embryos are exposed during early development. In vivo and in vitro studies have been performed showing that the use of nanocapsules as active substances carriers increases stability, bioavailability and biodistribution of drugs, such as melatonin, to the cells and tissues, improving their antioxidant properties. These properties can be modulated through the manipulation of formula composition, especially in relation to the supramolecular structures of the nanocapsule core and the surface area that greatly influences drug release mechanisms in biological environments. This study aimed to evaluate the effects of two types of melatonin-loaded nanocapsules with distinct supramolecular structures, polymeric (NC and lipid-core (LNC nanocapsules, on in vitro cultured bovine embryos. Embryonic development, apoptosis, reactive oxygen species (ROS production, and mRNA levels of genes involved in cell apoptosis, ROS and cell pluripotency were evaluated after supplementation of culture medium with non-encapsulated melatonin (Mel, melatonin-loaded polymeric nanocapsules (Mel-NC and melatonin-loaded lipid-core nanocapsules (Mel-LNC at 10-6, 10-9, and 10-12 M drug concentrations. The highest hatching rate was observed in embryos treated with 10-9 M Mel-LNC. When compared to Mel and Mel-NC treatments at the same concentration (10-9 M, Mel-LNC increased embryo cell number, decreased cell apoptosis and ROS levels, down-regulated mRNA levels of BAX, CASP3, and SHC1 genes, and up-regulated mRNA levels of CAT and SOD2 genes. These findings indicate that nanoencapsulation with LNC increases the protective effects of

  4. Effects of Two Types of Melatonin-Loaded Nanocapsules with Distinct Supramolecular Structures: Polymeric (NC) and Lipid-Core Nanocapsules (LNC) on Bovine Embryo Culture Model

    Science.gov (United States)

    Komninou, Eliza Rossi; Remião, Mariana Härter; Lucas, Caroline Gomes; Domingues, William Borges; Basso, Andrea Cristina; Jornada, Denise Soledade; Deschamps, João Carlos; Beck, Ruy Carlos Ruver; Pohlmann, Adriana Raffin; Bordignon, Vilceu; Seixas, Fabiana Kömmling; Campos, Vinicius Farias; Guterres, Silvia Stanisçuaski; Collares, Tiago

    2016-01-01

    Melatonin has been used as a supplement in culture medium to improve the efficiency of in vitro produced mammalian embryos. Through its ability to scavenge toxic oxygen derivatives and regulate cellular mRNA levels for antioxidant enzymes, this molecule has been shown to play a protective role against damage by free radicals, to which in vitro cultured embryos are exposed during early development. In vivo and in vitro studies have been performed showing that the use of nanocapsules as active substances carriers increases stability, bioavailability and biodistribution of drugs, such as melatonin, to the cells and tissues, improving their antioxidant properties. These properties can be modulated through the manipulation of formula composition, especially in relation to the supramolecular structures of the nanocapsule core and the surface area that greatly influences drug release mechanisms in biological environments. This study aimed to evaluate the effects of two types of melatonin-loaded nanocapsules with distinct supramolecular structures, polymeric (NC) and lipid-core (LNC) nanocapsules, on in vitro cultured bovine embryos. Embryonic development, apoptosis, reactive oxygen species (ROS) production, and mRNA levels of genes involved in cell apoptosis, ROS and cell pluripotency were evaluated after supplementation of culture medium with non-encapsulated melatonin (Mel), melatonin-loaded polymeric nanocapsules (Mel-NC) and melatonin-loaded lipid-core nanocapsules (Mel-LNC) at 10−6, 10−9, and 10−12 M drug concentrations. The highest hatching rate was observed in embryos treated with 10−9 M Mel-LNC. When compared to Mel and Mel-NC treatments at the same concentration (10−9 M), Mel-LNC increased embryo cell number, decreased cell apoptosis and ROS levels, down-regulated mRNA levels of BAX, CASP3, and SHC1 genes, and up-regulated mRNA levels of CAT and SOD2 genes. These findings indicate that nanoencapsulation with LNC increases the protective effects of

  5. Effects of Two Types of Melatonin-Loaded Nanocapsules with Distinct Supramolecular Structures: Polymeric (NC) and Lipid-Core Nanocapsules (LNC) on Bovine Embryo Culture Model.

    Science.gov (United States)

    Komninou, Eliza Rossi; Remião, Mariana Härter; Lucas, Caroline Gomes; Domingues, William Borges; Basso, Andrea Cristina; Jornada, Denise Soledade; Deschamps, João Carlos; Beck, Ruy Carlos Ruver; Pohlmann, Adriana Raffin; Bordignon, Vilceu; Seixas, Fabiana Kömmling; Campos, Vinicius Farias; Guterres, Silvia Stanisçuaski; Collares, Tiago

    2016-01-01

    Melatonin has been used as a supplement in culture medium to improve the efficiency of in vitro produced mammalian embryos. Through its ability to scavenge toxic oxygen derivatives and regulate cellular mRNA levels for antioxidant enzymes, this molecule has been shown to play a protective role against damage by free radicals, to which in vitro cultured embryos are exposed during early development. In vivo and in vitro studies have been performed showing that the use of nanocapsules as active substances carriers increases stability, bioavailability and biodistribution of drugs, such as melatonin, to the cells and tissues, improving their antioxidant properties. These properties can be modulated through the manipulation of formula composition, especially in relation to the supramolecular structures of the nanocapsule core and the surface area that greatly influences drug release mechanisms in biological environments. This study aimed to evaluate the effects of two types of melatonin-loaded nanocapsules with distinct supramolecular structures, polymeric (NC) and lipid-core (LNC) nanocapsules, on in vitro cultured bovine embryos. Embryonic development, apoptosis, reactive oxygen species (ROS) production, and mRNA levels of genes involved in cell apoptosis, ROS and cell pluripotency were evaluated after supplementation of culture medium with non-encapsulated melatonin (Mel), melatonin-loaded polymeric nanocapsules (Mel-NC) and melatonin-loaded lipid-core nanocapsules (Mel-LNC) at 10-6, 10-9, and 10-12 M drug concentrations. The highest hatching rate was observed in embryos treated with 10-9 M Mel-LNC. When compared to Mel and Mel-NC treatments at the same concentration (10-9 M), Mel-LNC increased embryo cell number, decreased cell apoptosis and ROS levels, down-regulated mRNA levels of BAX, CASP3, and SHC1 genes, and up-regulated mRNA levels of CAT and SOD2 genes. These findings indicate that nanoencapsulation with LNC increases the protective effects of melatonin

  6. Nanoscale infrared (IR) spectroscopy and imaging of structural lipids in human stratum corneum using an atomic force microscope to directly detect absorbed light from a tunable IR laser source.

    Science.gov (United States)

    Marcott, Curtis; Lo, Michael; Kjoller, Kevin; Domanov, Yegor; Balooch, Guive; Luengo, Gustavo S

    2013-06-01

    An atomic force microscope (AFM) and a tunable infrared (IR) laser source have been combined in a single instrument (AFM-IR) capable of producing ~200-nm spatial resolution IR spectra and absorption images. This new capability enables IR spectroscopic characterization of human stratum corneum at unprecendented levels. Samples of normal and delipidized stratum corneum were embedded, cross-sectioned and mounted on ZnSe prisms. A pulsed tunable IR laser source produces thermomechanical expansion upon absorption, which is detected through excitation of contact resonance modes in the AFM cantilever. In addition to reducing the total lipid content, the delipidization process damages the stratum corneum morphological structure. The delipidized stratum corneum shows substantially less long-chain CH2 -stretching IR absorption band intensity than normal skin. AFM-IR images that compare absorbances at 2930/cm (lipid) and 3290/cm (keratin) suggest that regions of higher lipid concentration are located at the perimeter of corneocytes in the normal stratum corneum.

  7. Trends in lipoplex physical properties dependent on cationic lipid structure, vehicle and complexation procedure do not correlate with biological activity.

    Science.gov (United States)

    Ferrari, M E; Rusalov, D; Enas, J; Wheeler, C J

    2001-04-01

    Using a group of structurally related cytofectins, the effects of different vehicle constituents and mixing techniques on the physical properties and biological activity of lipoplexes were systematically examined. Physical properties were examined using a combination of dye accessibility assays, centrifugation, gel electrophoresis and dynamic light scattering. Biological activity was examined using in vitro transfection. Lipoplexes were formulated using two injection vehicles commonly used for in vivo delivery (PBS pH 7.2 and 0.9% saline), and a sodium phosphate vehicle previously shown to enhance the biological activity of naked pDNA and lipoplex formulations. Phosphate was found to be unique in its effect on lipoplexes. Specifically, the accessible pDNA in lipoplexes formulated with cytofectins containing a gamma-amine substitution in the headgroup was dependent on alkyl side chain length and sodium phosphate concentration, but the same effects were not observed when using cytofectins containing a beta-OH headgroup substitution. The physicochemical features of the phosphate anion, which give rise to this effect in gamma-amine cytofectins, were deduced using a series of phosphate analogs. The effects of the formulation vehicle on transfection were found to be cell type-dependent; however, of the formulation variables examined, the liposome/pDNA mixing method had the greatest effect on transgene expression in vitro. Thus, though predictive physical structure relationships involving the vehicle and cytofectin components of the lipoplex were uncovered, they did not extrapolate to trends in biological activity.

  8. Comparison of structure and organization of cutaneous lipids in a reconstructed skin model and human skin: spectroscopic imaging and chromatographic profiling.

    Science.gov (United States)

    Tfayli, Ali; Bonnier, Franck; Farhane, Zeineb; Libong, Danielle; Byrne, Hugh J; Baillet-Guffroy, Arlette

    2014-06-01

    The use of animals for scientific research is increasingly restricted by legislation, increasing the demand for human skin models. These constructs present comparable bulk lipid content to human skin. However, their permeability is significantly higher, limiting their applicability as models of barrier function, although the molecular origins of this reduced barrier function remain unclear. This study analyses the stratum corneum (SC) of one such commercially available reconstructed skin model (RSM) compared with human SC by spectroscopic imaging and chromatographic profiling. Total lipid composition was compared by chromatographic analysis (HPLC). Raman spectroscopy was used to evaluate the conformational order, lateral packing and distribution of lipids in the surface and skin/RSM sections. Although HPLC indicates that all SC lipid classes are present, significant differences are observed in ceramide profiles. Raman imaging demonstrated that the RSM lipids are distributed in a non-continuous matrix, providing a better understanding of the limited barrier function.

  9. Shape fluctuations of large unilamellar lipid vesicles observed by laser light scattering: influence of the small-scale structure.

    Science.gov (United States)

    Brocca, Paola; Cantù, Laura; Corti, Mario; Del Favero, Elena; Motta, Simona

    2004-03-16

    In the present paper, we apply the dynamic laser light scattering technique to investigate the dependence of the characteristic times of thermally induced shape fluctuation of large unilamellar vesicles (LUVs) on bilayer composition. After addressing single-component LUVs made of two common phospholipids, dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC), we investigate the changes in vesicle shape fluctuation times due to the presence of cholesterol and gangliosides (GM1), added in small amounts. The experimental results show that the addition of a second component, even in small amount, to DMPC vesicles induces a change in membrane fluctuation times. Moreover, in the case of ganglioside addition, also the disposition of GM1 within the bilayer is of importance. Quite unexpectedly, the symmetric or asymmetric disposition of GM1 has opposite effects on bilayer dynamics, the first resulting in a "hardening" and the second in a "softening" of the membrane. Those results support that the small-scale structure of the bilayer is important in determining the overall dynamics of the vesicle. They also suggest that the physiological disposition of GM1 in the outer leaflet of real cells has a significative result in mechanical terms, positively affecting the dynamics of the membrane.

  10. Deuterium-labelled N-acyl-l-homoserine lactones (AHLs) - inter-kingdom signalling molecules - synthesis, structural studies, and interactions with model lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Jakubczyk, Dorota [Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe (Germany); Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Barth, Christoph; Anastassacos, Frances; Koelsch, Patrick; Schepers, Ute [Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Kubas, Adam; Fink, Karin [Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Brenner-Weiss, Gerald [Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Braese, Stefan [Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2012-04-15

    N-Acyl-l-homoserine lactones (AHLs) are synthesized by Gram-negative bacteria. These quorum-sensing molecules play an important role in the context of bacterial infection and biofilm formation. They also allow communication between microorganisms and eukaryotic cells (inter-kingdom signalling). However, very little is known about the entire mechanism of those interactions. Precise structural studies are required to analyse the different AHL isomers as only one form is biologically most active. Theoretical studies combined with experimental infrared and Raman spectroscopic data are therefore undertaken to characterise the obtained compounds. To mimic interactions between AHL and cell membranes, we studied the insertion of AHL in supported lipid bilayers, using vibrational sum-frequency-generation spectroscopy. Deuterium-labelled AHLs were thus synthesized. Starting from readily available deuterated fatty acids, a two-step procedure towards deuterated N-acyl-l-homoserine lactones with varying chain lengths is described. This included the acylation of Meldrum's acid followed by amidation. Additionally, the detailed analytical evaluation of the products is presented herein. (orig.)

  11. Characteristics of structured lipid prepared by lipase-catalyzed acidolysis of roasted sesame oil and caprylic acid in a bench-scale continuous packed bed reactor.

    Science.gov (United States)

    Kim, Byung Hee; Akoh, Casimir C

    2006-07-12

    Structured lipid (SL) was prepared from roasted sesame oil and caprylic acid (CA) by Rhizomucor miehei lipase-catalyzed acidolysis in a bench-scale continuous packed bed reactor. Total incorporation and acyl migration of CA in the SL were 42.5 and 3.1 mol %, respectively, and the half-life of the lipase was 19.2 days. The SL displayed different physical and chemical properties, less saturated dark brown color, lower viscosity, lower melting and crystallization temperature ranges, higher melting and crystallization enthalpies, higher smoke point, higher saponification value, and lower iodine value, in comparison to those of unmodified sesame oil. The oxidative stability of purified SL was lower than that of sesame oil. There were no differences in the contents of unsaponifiables including tocopherols and phytosterols. However, total sesame lignans content was decreased in SL due to the loss of sesamol when compared to sesame oil. Most of the 70 volatiles present in roasted sesame oil were removed from SL during short-path distillation of SL. These results indicate that the characteristics of SL are different from those of original sesame oil in several aspects except for the contents of tocopherols and phytosterols.

  12. Synthesis of structured lipid enriched with omega fatty acids and sn-2 palmitic acid by enzymatic esterification and its incorporation in powdered infant formula.

    Science.gov (United States)

    Nagachinta, Supakana; Akoh, Casimir C

    2013-05-08

    Structured lipid (SL) enriched with arachidonic (ARA) and docosahexaenoic (DHA) acids was produced from tripalmitin using Lipozyme TL IM. The effects of acyl donors, that is, free fatty acids vs fatty acid ethyl esters, on the reactions were compared. The highest total incorporation of ARA and DHA was obtained when the reaction continued for 24 h, at a substrate mole ratio of 9, using free fatty acids as acyl donors (acidolysis). The SL prepared by a large-scale acidolysis reaction contained 17.69 ± 0.09% total ARA, 10.75 ± 0.15% total DHA, and 48.53 ± 1.40% sn-2 palmitic acid. SL thermograms exhibited multiple peaks indicating complexity of the triacylglycerol (TAG) distribution. RP-HPLC analysis of SL revealed nine of 26 TAG molecular species that were similar to those of human milk fat. Powdered infant formulas containing the SL were prepared by wet-mixing/spray-drying and dry-blending methods. Formula prepared with microencapsulated SL and the dry-blending method had better oxidative stability and color quality.

  13. ENERGY-TRANSDUCING PROPERTIES OF PRIMARY PROTON PUMPS RECONSTITUTED INTO ARCHAEAL BIPOLAR LIPID VESICLES

    NARCIS (Netherlands)

    ELFERINK, MGL; DEWIT, JG; DRIESSEN, AJM; KONINGS, WN; Elferink, Marieke G.L.

    1993-01-01

    Archaeal lipids differ considerably from eubacterial and eukaryotic lipids in their structure and physical properties. From the membranes of the extreme thermophilic archaea Sulfolobus acidocaldarius a tetraether lipid fraction was isolated, which can form closed and stable monolayer liposomes in

  14. The molecular face of lipid rafts in model membranes

    NARCIS (Netherlands)

    Risselada, H. Jelger; Marrink, Siewert J.

    2008-01-01

    Cell membranes contain a large number of different lipid species. Such a multicomponent mixture exhibits a complex phase behavior with regions of structural and compositional heterogeneity. Especially domains formed in ternary mixtures, composed of saturated and unsaturated lipids together with

  15. Lipid Nanoparticles for Ocular Gene Delivery

    Directory of Open Access Journals (Sweden)

    Yuhong Wang

    2015-06-01

    Full Text Available Lipids contain hydrocarbons and are the building blocks of cells. Lipids can naturally form themselves into nano-films and nano-structures, micelles, reverse micelles, and liposomes. Micelles or reverse micelles are monolayer structures, whereas liposomes are bilayer structures. Liposomes have been recognized as carriers for drug delivery. Solid lipid nanoparticles and lipoplex (liposome-polycation-DNA complex, also called lipid nanoparticles, are currently used to deliver drugs and genes to ocular tissues. A solid lipid nanoparticle (SLN is typically spherical, and possesses a solid lipid core matrix that can solubilize lipophilic molecules. The lipid nanoparticle, called the liposome protamine/DNA lipoplex (LPD, is electrostatically assembled from cationic liposomes and an anionic protamine-DNA complex. The LPD nanoparticles contain a highly condensed DNA core surrounded by lipid bilayers. SLNs are extensively used to deliver drugs to the cornea. LPD nanoparticles are used to target the retina. Age-related macular degeneration, retinitis pigmentosa, and diabetic retinopathy are the most common retinal diseases in humans. There have also been promising results achieved recently with LPD nanoparticles to deliver functional genes and micro RNA to treat retinal diseases. Here, we review recent advances in ocular drug and gene delivery employing lipid nanoparticles.

  16. DMSO Induces Dehydration near Lipid Membrane Surfaces

    Science.gov (United States)

    Cheng, Chi-Yuan; Song, Jinsuk; Pas, Jolien; Meijer, Lenny H.H.; Han, Songi

    2015-01-01

    Dimethyl sulfoxide (DMSO) has been broadly used in biology as a cosolvent, a cryoprotectant, and an enhancer of membrane permeability, leading to the general assumption that DMSO-induced structural changes in cell membranes and their hydration water play important functional roles. Although the effects of DMSO on the membrane structure and the headgroup dehydration have been extensively studied, the mechanism by which DMSO invokes its effect on lipid membranes and the direct role of water in this process are unresolved. By directly probing the translational water diffusivity near unconfined lipid vesicle surfaces, the lipid headgroup mobility, and the repeat distances in multilamellar vesicles, we found that DMSO exclusively weakens the surface water network near the lipid membrane at a bulk DMSO mole fraction (XDMSO) of DMSO was found to effectively destabilize the hydration water structure at the lipid membrane surface at XDMSO 0.1, DMSO enters the lipid interface and restricts the lipid headgroup motion. We postulate that DMSO acts as an efficient cryoprotectant even at low concentrations by exclusively disrupting the water network near the lipid membrane surface, weakening the cohesion between water and adhesion of water to the lipid headgroups, and so mitigating the stress induced by the volume change of water during freeze-thaw. PMID:26200868

  17. Lipides polaires marins

    OpenAIRE

    Fanni Jacques; Linder Michel; Parmentier Michel

    2004-01-01

    Les lipides polaires marins, notamment les phospholipides (PL), retiennent depuis quelques années l’attention des chercheurs et des industriels en raison de leur composition, particulièrement riche en acides gras polyinsaturés à longue chaîne (AGPI-LC). Ils combinent ainsi les propriétés reconnues des AGPI-LC à l’intérêt métabolique et structural des phospholipides. Les sources sont nombreuses et d’accès très diversifié. Le défi industriel provient de leurs caractéristiques amphiphiles et aro...

  18. Structural lipid changes and NKA activity of gill cells´ basolateral membranes as response to increasing salinity and atrazine stressors in sea lamprey (Petromyzon marinus, L. juveniles

    Directory of Open Access Journals (Sweden)

    Maria João Lança

    2015-12-01

    Modulation of BLM lipids associated with NKA activity seems to be the strategy adopted by gill cells of juveniles to compensate for osmotic and ionic stressors and for contact/resistance to ATZ exposure.

  19. Encapsulation with structured triglycerides

    Science.gov (United States)

    Lipids provide excellent materials to encapsulate bioactive compounds for food and pharmaceutical applications. Lipids are renewable, biodegradable, and easily modified to provide additional chemical functionality. The use of structured lipids that have been modified with photoactive properties are ...

  20. Stratum Corneum Barrier Lipids in Cholesteatoma

    DEFF Research Database (Denmark)

    Svane-Knudsen, V; Halkier-Sørensen, L; Rasmussen, G

    2000-01-01

    emerged. When the corneocyte reaches the transitional stage to the stratum corneum, the Odland bodies accumulate near the cell membrane and discharge their contents of lipid and enzymes. The lipids are reorganized into multiple long sheets of lamellar structures that embrace the keratinized corneocytes...

  1. Lipid polarity and sorting in epithelial cells

    NARCIS (Netherlands)

    van Meer, G.; Simons, K.

    1988-01-01

    Apical and basolateral membrane domains of epithelial cell plasma membranes possess unique lipid compositions. The tight junction, the structure separating the two domains, forms a diffusion barrier for membrane components and thereby prevents intermixing of the two sets of lipids. The barrier appar

  2. Keratins and lipids in ethnic hair.

    Science.gov (United States)

    Cruz, C F; Fernandes, M M; Gomes, A C; Coderch, L; Martí, M; Méndez, S; Gales, L; Azoia, N G; Shimanovich, U; Cavaco-Paulo, A

    2013-06-01

    Human hair has an important and undeniable relevance in society due to its important role in visual appearance and social communication. Hair is mainly composed of structural proteins, mainly keratin and keratin associated proteins and lipids. Herein, we report a comprehensive study of the content and distribution of the lipids among ethnic hair, African, Asian and Caucasian hair. More interestingly, we also report the study of the interaction between those two main components of hair, specifically, the influence of the hair internal lipids in the structure of the hair keratin. This was achieved by the use of a complete set of analytical tools, such as thin layer chromatography-flame ionization detector, X-ray analysis, molecular dynamics simulation and confocal microscopy. The experimental results indicated different amounts of lipids on ethnic hair compositions and higher percentage of hair internal lipids in African hair. In this type of hair, the axial diffraction of keratin was not observed in X-ray analysis, but after hair lipids removal, the keratin returned to its typical packing arrangement. In molecular dynamic simulation, lipids were shown to intercalate dimers of keratin, changing its structure. From those results, we assume that keratin structure may be influenced by higher concentration of lipids in African hair. © 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  3. Glycosphingolipid-facilitated membrane insertion and internalization of cobra cardiotoxin. The sulfatide.cardiotoxin complex structure in a membrane-like environment suggests a lipid-dependent cell-penetrating mechanism for membrane binding polypeptides.

    Science.gov (United States)

    Wang, Chia-Hui; Liu, Jyung-Hurng; Lee, Shao-Chen; Hsiao, Chwan-Deng; Wu, Wen-Guey

    2006-01-06

    Cobra cardiotoxins, a family of basic polypeptides having lipid- and heparin-binding capacities similar to the cell-penetrating peptides, induce severe tissue necrosis and systolic heart arrest in snakebite victims. Whereas cardiotoxins are specifically retained on the cell surface via heparan sulfate-mediated processes, their lipid binding ability appears to be responsible, at least in part, for cardiotoxin-induced membrane leakage and cell death. Although the exact role of lipids involved in toxin-mediated cytotoxicity remains largely unknown, monoclonal anti-sulfatide antibody O4 has recently been shown to inhibit the action of CTX A3, the major cardiotoxin from Taiwan cobra venom, on cardiomyocytes by preventing cardiotoxin-induced membrane leakage and CTX A3 internalization into mitochondria. Here, we show that anti-sulfatide acts by blocking the binding of CTX A3 to the sulfatides in the plasma membrane to prevent sulfatide-dependent CTX A3 membrane pore formation and internalization. We also describe the crystal structure of a CTX A3-sulfatide complex in a membrane-like environment at 2.3 angstroms resolution. The unexpected orientation of the sulfatide fatty chains in the structure allows prediction of the mode of toxin insertion into the plasma membrane. CTX A3 recognizes both the headgroup and the ceramide interfacial region of sulfatide to induce a lipid conformational change that may play a key role in CTX A3 oligomerization and cellular internalization. This proposed lipid-mediated toxin translocation mechanism may also shed light on the cellular uptake mechanism of the amphiphilic cell-penetrating peptides known to involve multiple internalization pathways.

  4. Peptaibol antiamoebin I: spatial structure, backbone dynamics, interaction with bicelles and lipid-protein nanodiscs, and pore formation in context of barrel-stave model.

    Science.gov (United States)

    Shenkarev, Zakhar O; Paramonov, Alexander S; Lyukmanova, Ekaterina N; Gizatullina, Albina K; Zhuravleva, Anastasia V; Tagaev, Andrey A; Yakimenko, Zoya A; Telezhinskaya, Irina N; Kirpichnikov, Mikhail P; Ovchinnikova, Tatiana V; Arseniev, Alexander S

    2013-05-01

    Antiamoebin I (Aam-I) is a membrane-active peptaibol antibiotic isolated from fungal species belonging to the genera Cephalosporium, Emericellopsis, Gliocladium, and Stilbella. In comparison with other 16-amino acid-residue peptaibols, e.g., zervamicin IIB (Zrv-IIB), Aam-I possesses relatively weak biological and channel-forming activities. In MeOH solution, Aam-I demonstrates fast cooperative transitions between right-handed and left-handed helical conformation of the N-terminal (1-8) region. We studied Aam-I spatial structure and backbone dynamics in the membrane-mimicking environment (DMPC/DHPC bicelles)(1) ) by heteronuclear (1) H,(13) C,(15) N-NMR spectroscopy. Interaction with the bicelles stabilizes the Aam-I right-handed helical conformation retaining significant intramolecular mobility on the ms-μs time scale. Extensive ms-μs dynamics were also detected in the DPC and DHPC micelles and DOPG nanodiscs. In contrast, Zrv-IIB in the DPC micelles demonstrates appreciably lesser mobility on the μs-ms time scale. Titration with Mn(2+) and 16-doxylstearate paramagnetic probes revealed Aam-I binding to the bicelle surface with the N-terminus slightly immersed into hydrocarbon region. Fluctuations of the Aam-I helix between surface-bound and transmembrane (TM) state were observed in the nanodisc membranes formed from the short-chain (diC12 : 0) DLPC/DLPG lipids. All the obtained experimental data are in agreement with the barrel-stave model of TM pore formation, similarly to the mechanism proposed for Zrv-IIB and other peptaibols. The observed extensive intramolecular dynamics explains the relatively low activity of Aam-I.

  5. Structure-specific effects of lipidated oxytocin analogs on intracellular calcium levels, parental behavior, and oxytocin concentrations in the plasma and cerebrospinal fluid in mice.

    Science.gov (United States)

    Cherepanov, Stanislav M; Yokoyama, Shigeru; Mizuno, Akira; Ichinose, Wataru; Lopatina, Olga; Shabalova, Anna A; Salmina, Alla B; Yamamoto, Yasuhiko; Okamoto, Hiroshi; Shuto, Satoshi; Higashida, Haruhiro

    2017-02-01

    Oxytocin (OT) is a neuroendocrine nonapeptide that plays an important role in social memory and behavior. Nasal administration of OT has been shown to improve trust in healthy humans and social interaction in autistic subjects in some clinical trials. As a central nervous system (CNS) drug, however, OT has two unfavorable characteristics: OT is short-acting and shows poor permeability across the blood-brain barrier, because it exists in charged form in the plasma and has short half-life. To overcome these drawbacks, an analog with long-lasting effects is required. We previously synthesized the analog, lipo-oxytocin-1 (LOT-1), in which two palmitoyl groups are conjugated to the cysteine and tyrosine residues. In this study, we synthesized and evaluated the analogs lipo-oxytocin-2 (LOT-2) and lipo-oxytocin-3 (LOT-3), which feature the conjugation of one palmitoyl group at the cysteine and tyrosine residues, respectively. In human embryonic kidney-293 cells overexpressing human OT receptors, these three LOTs demonstrated comparably weak effects on the elevation of intracellular free calcium concentrations after OT receptor activation, compared to the effects of OT. The three LOTs and OT exhibited different time-dependent effects on recovery from impaired pup retrieval behavior in sires of CD38-knockout mice. Sires treated with LOT-1 showed the strongest effect, whereas others had no or little effects at 24 h after injection. These results indicated that LOTs have structure-specific agonistic effects, and suggest that lipidation of OT might have therapeutic benefits for social impairment.

  6. Studies of reaction variables for lipase-catalyzed production of alpha-linolenic acid enriched structured lipid and oxidative stability with antioxidants.

    Science.gov (United States)

    Mitra, Kanika; Shin, Jung-Ah; Lee, Jeung-Hee; Kim, Seong-Ai; Hong, Soon-Taek; Sung, Chang-Keun; Xue, Cheng Lian; Lee, Ki-Teak

    2012-01-01

    Alpha-linolenic acid (ALA) enriched structured lipid (SL) was produced by lipase-catalyzed interesterification from perilla oil (PO) and corn oil (CO). The effects of different reaction conditions (substrate molar ratio [PO/CO 1:1 to 1:3], reaction time [0 to 24 h], and reaction temperature [55 to 65 °C]) were studied. Lipozyme RM IM from Rhizomucor miehei was used as biocatalyst. We obtained 32.39% of ALA in SL obtained under the optimized conditions (molar ratio-1:1 [PO:CO], temperature-60 °C, reaction time-15 h). In SL, the major triacylglycerol (TAG) species (linolenoyl-linolenoyl-linolenoyl glycerol [LnLnLn], linolenoyl-linolenoyl-linoleoyl glycerol [LnLnL]) mainly from PO and linoleoyl-linoleoyl-oleoyl glycerol (LLO), linoleoyl-oleoyl-oleoyl glycerol (LOO), palmitoyl-linoleoyl-oleoyl glycerol (PLO) from CO decreased while linolenoyl-linolenoyl-oleoyl glycerol (LnLnO) (18.41%), trilinolein (LLL) (9.06%), LLO (16.66%), palmitoyl-linoleoyl-linoleoyl glycerol (PLL) (9.69%) were increased compared to that of physical blend. Total tocopherol content (28.01 mg/100 g), saponification value (SV) (192.2), and iodine value (IV) (161.9) were obtained. Furthermore, oxidative stability of the SL was also investigated by addition of 3 different antioxidants (each 200 ppm of rosemary extract [SL-ROS], BHT [SL-BHT], catechin [SL-CAT]) was added into SL and stored in 60 °C oven for 30 d. 2-Thiobabituric acid-reactive substances (TBARS) value was 0.16 mg/kg in SL-CAT and 0.18 mg/kg in SL-ROS as compared with 0.22 mg/kg in control (SL) after oxidation. The lowest peroxide value (POV, 200.9 meq/kg) and longest induction time (29.88 h) was also observed in SL-CAT.

  7. The effects of processing and mastication on almond lipid bioaccessibility using novel methods of in vitro digestion modelling and micro-structural analysis.

    Science.gov (United States)

    Mandalari, Giuseppina; Grundy, Myriam M-L; Grassby, Terri; Parker, Mary L; Cross, Kathryn L; Chessa, Simona; Bisignano, Carlo; Barreca, Davide; Bellocco, Ersilia; Laganà, Giuseppina; Butterworth, Peter J; Faulks, Richard M; Wilde, Peter J; Ellis, Peter R; Waldron, Keith W

    2014-11-14

    A number of studies have demonstrated that consuming almonds increases satiety but does not result in weight gain, despite their high energy and lipid content. To understand the mechanism of almond digestion, in the present study, we investigated the bioaccessibility of lipids from masticated almonds during in vitro simulated human digestion, and determined the associated changes in cell-wall composition and cellular microstructure. The influence of processing on lipid release was assessed by using natural raw almonds (NA) and roasted almonds (RA). Masticated samples from four healthy adults (two females, two males) were exposed to a dynamic gastric model of digestion followed by simulated duodenal digestion. Between 7·8 and 11·1 % of the total lipid was released as a result of mastication, with no significant differences between the NA and RA samples. Significant digestion occurred during the in vitro gastric phase (16·4 and 15·9 %) and the in vitro duodenal phase (32·2 and 32·7 %) for the NA and RA samples, respectively. Roasting produced a smaller average particle size distribution post-mastication; however, this was not significant in terms of lipid release. Light microscopy showed major changes that occurred in the distribution of lipid in all cells after the roasting process. Further changes were observed in the surface cells of almond fragments and in fractured cells after exposure to the duodenal environment. Almond cell walls prevented lipid release from intact cells, providing a mechanism for incomplete nutrient absorption in the gut. The composition of almond cell walls was not affected by processing or simulated digestion.

  8. Influence of Tribulus terrestris extract on lipid profile and endothelial structure in developing atherosclerotic lesions in the aorta of rabbits on a high-cholesterol diet.

    Science.gov (United States)

    Tuncer, M Altug; Yaymaci, Bengi; Sati, Leyla; Cayli, Sevil; Acar, Goksemin; Altug, Tuncay; Demir, Ramazan

    2009-01-01

    The aim of this study was to investigate the pleotropic effects of an extract of a traditional herb, Tribulus terrestris (TT), on the lipid profile and vascular endothelium of the abdominal aorta in New Zealand rabbits fed a cholesterol-rich diet. Eighteen rabbits were randomly divided into three groups (n=6 for each). One experimental group (EG-I) was given a cholesterol-rich diet, a second experimental group (EG-II) was treated with TT following a cholesterol-rich diet, and a control group (CG) was fed a standard diet. Blood samples were collected on day 0 and then at weeks 4 and 12 to determine total serum cholesterol (TC), high density lipid-cholesterol (HDL-C), low density lipid-cholesterol (LDL-C) and triglyceride (TG) levels. Tissues were collected from the abdominal aorta for immunohistochemistry and transmission and scanning electron microscopy. In EG-II, the serum lipid profile was significantly lower than that of EG-I at week 12 with a reduction of TC: 65%; LDL-C: 66%; HDL-C: 64%; TG: 55%. Ultrastructural analysis revealed that endothelial damage was more prominent in EG-I compared to EG-II. The ruptured endothelial linings and damaged cellular surfaces increased in EG-I compared to EG-II. Our data indicate that dietary intake of TT can significantly lower serum lipid profiles, decrease endothelial cellular surface damage and rupture and may partially repair the endothelial dysfunction resulting from hyperlipidemia.

  9. The interaction between purple membrane and membrane lipid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Bacteriorhodopsin in purple membrane was reconstituted into different lipid vesicles. The effect of three different lipids on the structure and function of bacteriorhodopsin in lipid vesicles was studied by the observation on freeze-fracture eletron microscopy, the rotational diffusion of bacteriorhodopsin in lipid vesicles, the measurement of absorption spectrum, and the absorbance change with time. For these prepared samples, the results showed that DMPC was the stable lipid environment of bacteriorhodopsin; egg-pc causeed the loss of retinal chromophore of bacteriorhodopsin and it was not reversible change, cholesterol could stabilize the bacteriorhodopsin in lipid environment,but it caused the aggregation of bacteriorhodopsin.

  10. Lipid corralling and poloxamer squeeze-out in membranes

    DEFF Research Database (Denmark)

    Wu, G.H.; Majewski, J.; Ege, C.;

    2004-01-01

    Using x-ray scattering measurements we have quantitatively determined the effect of poloxamer 188 (P188), a polymer known to seal damaged membranes, on the structure of lipid monolayers. P188 selectively inserts into low lipid-density regions of the membrane and "corrals" lipid molecules to pack...... tightly, leading to unexpected Bragg peaks at low nominal lipid density and inducing lipid/poloxamer phase separation. At tighter lipid packing, the once inserted P188 is squeezed out, allowing the poloxamer to gracefully exit when the membrane integrity is restored....

  11. Lipid Bilayer Composition Affects Transmembrane Protein Orientation and Function

    Directory of Open Access Journals (Sweden)

    Katie D. Hickey

    2011-01-01

    Full Text Available Sperm membranes change in structure and composition upon ejaculation to undergo capacitation, a molecular transformation which enables spermatozoa to undergo the acrosome reaction and be capable of fertilization. Changes to the membrane environment including lipid composition, specifically lipid microdomains, may be responsible for enabling capacitation. To study the effect of lipid environment on proteins, liposomes were created using lipids extracted from bull sperm membranes, with or without a protein (Na+ K+-ATPase or -amylase. Protein incorporation, function, and orientation were determined. Fluorescence resonance energy transfer (FRET confirmed protein inclusion in the lipid bilayer, and protein function was confirmed using a colourometric assay of phosphate production from ATP cleavage. In the native lipid liposomes, ATPase was oriented with the subunit facing the outer leaflet, while changing the lipid composition to 50% native lipids and 50% exogenous lipids significantly altered this orientation of Na+ K+-ATPase within the membranes.

  12. Morphological and Stress Vulnerability Indices for Human Coronary Plaques and Their Correlations with Cap Thickness and Lipid Percent: An IVUS-Based Fluid-Structure Interaction Multi-patient Study.

    Directory of Open Access Journals (Sweden)

    Liang Wang

    2015-12-01

    Full Text Available Plaque vulnerability, defined as the likelihood that a plaque would rupture, is difficult to quantify due to lack of in vivo plaque rupture data. Morphological and stress-based plaque vulnerability indices were introduced as alternatives to obtain quantitative vulnerability assessment. Correlations between these indices and key plaque features were investigated. In vivo intravascular ultrasound (IVUS data were acquired from 14 patients and IVUS-based 3D fluid-structure interaction (FSI coronary plaque models with cyclic bending were constructed to obtain plaque wall stress/strain and flow shear stress for analysis. For the 617 slices from the 14 patients, lipid percentage, min cap thickness, critical plaque wall stress (CPWS, strain (CPWSn and flow shear stress (CFSS were recorded, and cap index, lipid index and morphological index were assigned to each slice using methods consistent with American Heart Association (AHA plaque classification schemes. A stress index was introduced based on CPWS. Linear Mixed-Effects (LME models were used to analyze the correlations between the mechanical and morphological indices and key morphological factors associated with plaque rupture. Our results indicated that for all 617 slices, CPWS correlated with min cap thickness, cap index, morphological index with r = -0.6414, 0.7852, and 0.7411 respectively (p<0.0001. The correlation between CPWS and lipid percentage, lipid index were weaker (r = 0.2445, r = 0.2338, p<0.0001. Stress index correlated with cap index, lipid index, morphological index positively with r = 0.8185, 0.3067, and 0.7715, respectively, all with p<0.0001. For all 617 slices, the stress index has 66.77% agreement with morphological index. Morphological and stress indices may serve as quantitative plaque vulnerability assessment supported by their strong correlations with morphological features associated with plaque rupture. Differences between the two indices may lead to better plaque

  13. Combining vibrational biomolecular spectroscopy with chemometric techniques for the study of response and sensitivity of molecular structures/functional groups mainly related to lipid biopolymer to various processing applications.

    Science.gov (United States)

    Yu, Gloria Qingyu; Yu, Peiqiang

    2015-09-01

    The objectives of this project were to (1) combine vibrational spectroscopy with chemometric multivariate techniques to determine the effect of processing applications on molecular structural changes of lipid biopolymer that mainly related to functional groups in green- and yellow-type Crop Development Centre (CDC) pea varieties [CDC strike (green-type) vs. CDC meadow (yellow-type)] that occurred during various processing applications; (2) relatively quantify the effect of processing applications on the antisymmetric CH3 ("CH3as") and CH2 ("CH2as") (ca. 2960 and 2923 cm(-1), respectively), symmetric CH3 ("CH3s") and CH2 ("CH2s") (ca. 2873 and 2954 cm(-1), respectively) functional groups and carbonyl C=O ester (ca. 1745 cm(-1)) spectral intensities as well as their ratios of antisymmetric CH3 to antisymmetric CH2 (ratio of CH3as to CH2as), ratios of symmetric CH3 to symmetric CH2 (ratio of CH3s to CH2s), and ratios of carbonyl C=O ester peak area to total CH peak area (ratio of C=O ester to CH); and (3) illustrate non-invasive techniques to detect the sensitivity of individual molecular functional group to the various processing applications in the recently developed different types of pea varieties. The hypothesis of this research was that processing applications modified the molecular structure profiles in the processed products as opposed to original unprocessed pea seeds. The results showed that the different processing methods had different impacts on lipid molecular functional groups. Different lipid functional groups had different sensitivity to various heat processing applications. These changes were detected by advanced molecular spectroscopy with chemometric techniques which may be highly related to lipid utilization and availability. The multivariate molecular spectral analyses, cluster analysis, and principal component analysis of original spectra (without spectral parameterization) are unable to fully distinguish the structural differences in the

  14. Microemulsion extrusion technique : a new method to produce lipid nanoparticles

    NARCIS (Netherlands)

    de Jesus, Marcelo Bispo; Radaic, Allan; Zuhorn, Inge S.; de Paula, Eneida

    2013-01-01

    Solid lipid nanoparticles (SLN) and nano-structured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization

  15. Microemulsion extrusion technique : a new method to produce lipid nanoparticles

    NARCIS (Netherlands)

    de Jesus, Marcelo Bispo; Radaic, Allan; Zuhorn, Inge S.; de Paula, Eneida

    2013-01-01

    Solid lipid nanoparticles (SLN) and nano-structured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization

  16. Importance of the hexagonal lipid phase in biological membrane organisation

    Directory of Open Access Journals (Sweden)

    Juliette eJouhet

    2013-12-01

    Full Text Available Abstract:Domains are present in every natural membrane. They are characterised by a distinctive protein and/or lipid composition. Their size is highly variable from the nano- to the micrometer scale. The domains confer specific properties to the membrane leading to original structure and function. The determinants leading to domain organisation are therefore important but remain obscure. This review presents how the ability of lipids to organize into hexagonal II or lamellar phases can promote particular local structures within membranes. Since biological membranes are composed of a mixture of lipids, each with distinctive biophysical properties, lateral and transversal sorting of lipids can promote creation of domains inside the membrane through local modulation of the lipid phase. Lipid biophysical properties have been characterized for long based on in vitro analyses using non-natural lipid molecules; their re-examinations using natural lipids might open interesting perspectives on membrane architecture occurring in vivo in various cellular and physiological contexts.

  17. Charge-reversal Lipids, Peptide-based Lipids, and Nucleoside-based Lipids for Gene Delivery

    Science.gov (United States)

    LaManna, Caroline M.; Lusic, Hrvoje; Camplo, Michel; McIntosh, Thomas J.; Barthélémy, Philippe; Grinstaff, Mark W.

    2013-01-01

    headgroup into the lipid provides a mechanism to affect the binding of the lipid to the nucleic acid, to influence the supramolecular lipoplex structure, and to enhance gene transfection activity. Lastly, we discuss the in-vitro successes we have had when using lipids possessing a nucleoside headgroup to create unique self-assembled structures and to deliver DNA to cells. In this Account, we state our hypotheses and design elements as well as describe the techniques that we have utilized in our research, in order to provide readers with the tools to characterize and engineer new vectors. PMID:22439686

  18. Doxorubicin Lipid Complex Injection

    Science.gov (United States)

    Doxorubicin lipid complex is used to treat ovarian cancer that has not improved or that has worsened after treatment with other medications. Doxorubicin lipid complex is also used to treat Kaposi's ...

  19. Irinotecan Lipid Complex Injection

    Science.gov (United States)

    Irinotecan lipid complex is used in combination with other medications to treat pancreatic cancer that has spread to other ... worsened after treatment with other chemotherapy medications. Irinotecan lipid complex is in a class of antineoplastic medications ...

  20. Daunorubicin Lipid Complex Injection

    Science.gov (United States)

    Daunorubicin lipid complex is used to treat advanced Kaposi's sarcoma (a type of cancer that causes abnormal tissue to ... body) related to acquired immunodeficiency syndrome (AIDS). Daunorubicin lipid complex is in a class of medications called ...

  1. Vincristine Lipid Complex Injection

    Science.gov (United States)

    Vincristine lipid complex is used to treat a certain type of acute lymphoblastic leukemia (ALL; a type of cancer ... least two different treatments with other medications. Vincristine lipid complex is in a class of medications called ...

  2. Parenteral Nutrition and Lipids.

    Science.gov (United States)

    Raman, Maitreyi; Almutairdi, Abdulelah; Mulesa, Leanne; Alberda, Cathy; Beattie, Colleen; Gramlich, Leah

    2017-04-14

    Lipids have multiple physiological roles that are biologically vital. Soybean oil lipid emulsions have been the mainstay of parenteral nutrition lipid formulations for decades in North America. Utilizing intravenous lipid emulsions in parenteral nutrition has minimized the dependence on dextrose as a major source of nonprotein calories and prevents the clinical consequences of essential fatty acid deficiency. Emerging literature has indicated that there are benefits to utilizing alternative lipids such as olive/soy-based formulations, and combination lipids such as soy/MCT/olive/fish oil, compared with soybean based lipids, as they have less inflammatory properties, are immune modulating, have higher antioxidant content, decrease risk of cholestasis, and improve clinical outcomes in certain subgroups of patients. The objective of this article is to review the history of IVLE, their composition, the different generations of widely available IVLE, the variables to consider when selecting lipids, and the complications of IVLE and how to minimize them.

  3. Biologic Activity of Porphyromonas endodontalis complex lipids

    Science.gov (United States)

    Mirucki, Christopher S.; Abedi, Mehran; Jiang, Jin; Zhu, Qiang; Wang, Yu-Hsiung; Safavi, Kamran E.; Clark, Robert B.; Nichols, Frank C.

    2014-01-01

    Introduction Periapical infections secondary to pulpal necrosis are associated with bacterial contamination of the pulp. Porphyromonas endodontalis, a Gram-negative organism, is considered to be a pulpal pathogen. P. gingivalis is phylogenetically related to P. endodontalis and synthesizes several classes of novel complex lipids that possess biological activity, including the capacity to promote osteoclastogenesis and osteoclast activation. The purpose of this study was to extract and characterize constituent lipids of P. endodontalis, and evaluate their capacity to promote pro-inflammatory secretory responses in the macrophage cell line, RAW 264.7, as well as their capacity to promote osteoclastogenesis and inhibit osteoblast activity. Methods Constituent lipids of both organisms were fractionated by HPLC and were structurally characterized using electrospray-mass spectrometry (ESI-MS) or ESI-MS/MS. The virulence potential of P. endodontalis lipids was then compared with known biologically active lipids isolated from P. gingivalis. Results P. endodontalis total lipids were shown to promote TNF-α secretion from RAW 264.7 cells and the serine lipid fraction appeared to account for the majority of this effect. P. endodontalis lipid preparations also increased osteoclast formation from RAW 264.7 cells but osteoblast differentiation in culture was inhibited and appeared to be dependent on TLR2 expression. Conclusions These effects underscore the importance of P. endodontalis lipids in promoting inflammatory and bone cell activation processes that could lead to periapical pathology. PMID:25146013

  4. Impact of Lipid Oxidization on Vertical Structures and Electrostatics of Phospholipid Monolayers Revealed by Combination of Specular X-ray Reflectivity and Grazing-Incidence X-ray Fluorescence.

    Science.gov (United States)

    Korytowski, Agatha; Abuillan, Wasim; Makky, Ali; Konovalov, Oleg; Tanaka, Motomu

    2015-07-30

    The influence of phospholipid oxidization of floating monolayers on the structure perpendicular to the global plane and on the density profiles of ions near the lipid monolayer has been investigated by a combination of grazing incidence X-ray fluorescence (GIXF) and specular X-ray reflectivity (XRR). Systematic variation of the composition of the floating monolayers unravels changes in the thickness, roughness and electron density of the lipid monolayers as a function of molar fraction of oxidized phospholipids. Simultaneous GIXF measurements enable one to qualitatively determine the element-specific density profiles of monovalent (K(+) or Cs(+)) and divalent ions (Ca(2+)) in the vicinity of the interface in the presence and absence of two types of oxidized phospholipids (PazePC and PoxnoPC) with high spatial accuracy (±5 Å). We found the condensation of Ca(2+) near carboxylated PazePC was more pronounced compared to PoxnoPC with an aldehyde group. In contrast, the condensation of monovalent ions could hardly be detected even for pure oxidized phospholipid monolayers. Moreover, pure phospholipid monolayers exhibited almost no ion specific condensation near the interface. The quantitative studies with well-defined floating monolayers revealed how the elevation of lipid oxidization level alters the structures and functions of cell membranes.

  5. Lipid nanoparticle interactions and assemblies

    Science.gov (United States)

    Preiss, Matthew Ryan

    Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron

  6. Lipid emulsions

    Directory of Open Access Journals (Sweden)

    Robins, Margaret M.

    2000-04-01

    Full Text Available Emulsions are liquid-liquid mixtures with one liquid contained as droplets within the other. The droplets are typically 1mm in diameter, and the properties of the emulsions are very dependent on the droplet structure, which is stabilised by surface-active emulsifier molecules. Most food emulsions are made from the raw ingredients using an homogenisation process to form small droplets. The paper describes methods of measuring droplet size and emulsion stability, and discusses the physical origin of emulsion texture, flavour and appearance.Las emulsiones son mezclas líquido-líquido con un líquido contenido en forma de gotas dentro de otro líquido. Las gotas tienen normalmente 1 mm de diámetro y las propiedades de las emulsiones dependen en gran medida de la estructura de la gota, la cual está estabilizada por las moléculas emulsionantes. La mayoría de las emulsiones alimenticias están constituidas a partir de materias primas usando un proceso de homogeneización que permite formar gotas pequeñas. El artículo describe métodos de medida del tamaño de gota y estabilidad de las emulsiones, y discute el origen físico de la textura, flavor y apariencia de la emulsión.

  7. Cyclohexane Rings Reduce Membrane Permeability to Small Ions in Archaea-Inspired Tetraether Lipids.

    Science.gov (United States)

    Koyanagi, Takaoki; Leriche, Geoffray; Onofrei, David; Holland, Gregory P; Mayer, Michael; Yang, Jerry

    2016-01-26

    Extremophile archaeal organisms overcome problems of membrane permeability by producing lipids with structural elements that putatively improve membrane integrity compared to lipids from other life forms. Herein, we describe a series of lipids that mimic some key structural features of archaeal lipids, such as: 1) single tethering of lipid tails to create fully transmembrane tetraether lipids and 2) the incorporation of small rings into these tethered segments. We found that membranes formed from pure tetraether lipids leaked small ions at a rate that was about two orders of magnitude slower than common bilayer-forming lipids. Incorporation of cyclopentane rings into the tetraether lipids did not affect membrane leakage, whereas a cyclohexane ring reduced leakage by an additional 40 %. These results show that mimicking certain structural features of natural archaeal lipids results in improved membrane integrity, which may help overcome limitations of many current lipid-based technologies.

  8. The antioxidant behaviour of melatonin and structural analogues during lipid peroxidation depends not only on their functional groups but also on the assay system.

    Science.gov (United States)

    Fagali, Natalia; Catalá, Angel

    2012-07-13

    There is no general agreement yet on the antioxidant effect of pineal indoles against lipid peroxidation. Accordingly, the main goal of the present work was to study the antioxidant activity of melatonin (MLT), N-acetylserotonin (NAS), 5-HO-tryptophan (5HO-TRP) and 5-methoxytryptamine (5MTP) in two different lipid systems with high content of polyunsaturated fatty acids (PUFAs): triglycerides (rich in 20:5 n-3, 22:6 n-3) dissolved in chloroform and sonicated liposomes made of retinal lipids (rich in 22:6 n-3). In the triglyceride-chloroform-system the peroxidation reaction was initiated by cumene hydroperoxide (CHP) whereas liposomes were peroxidized with Fe(2+). The techniques employed at the present work were: (1) TBARS production, (2) DPPH assay, (3) determination of conjugated dienes production and (4) analysis of fatty acid profile by GC-MS. Butylated hydroxytoluene (BHT) was employed as a reference because of its well known antioxidant capacity. Our results showed that MLT and 5MTP were unable to protect PUFAs against lipid peroxidation in both systems, whereas NAS and 5HO-TRP were better antioxidants that BHT in the triglyceride-system but ineffective in the liposome-system. We conclude that the antioxidant behaviour of pineal indoles depends not only on their functional groups but also on the assay system and could be explained by the polar paradox theory.

  9. Abstracts of Plenary Lectures and Posters. International Symposium of the Structure and Function of Plant Lipids (7th) held in Davis, California on July 27-August 1, 1986,

    Science.gov (United States)

    1986-08-01

    isolated from oil palm (Elaeis guineensis and £Liete oLeifera) mesocarp 16 - 20 weeks after anthesis. Embryoids (EZaeis m’neenois) at different...fruit and was maximum at 20 weeks. The embryoid protoplasts were more active in lipid biosynthesis compared to mesocarp protoplasts and incorporated

  10. Synergistic effects in gene delivery-a structure-activity approach to the optimisation of hybrid dendritic-lipidic transfection agents.

    Science.gov (United States)

    Jones, Simon P; Gabrielson, Nathan P; Pack, Daniel W; Smith, David K

    2008-10-21

    Novel gene delivery agents based on combining cholesterol units with spermine-functionalised dendrons exhibit enhanced transfection ability-we report significant synergistic effects in mixed (hybrid) systems which combine aspects of both main classes of synthetic vectors, i.e., cationic polymers and lipids.

  11. Temperature dependent heterogeneous rotational correlation in lipids

    Science.gov (United States)

    Dadashvand, Neda; Othon, Christina M.

    2016-12-01

    Lipid structures exhibit complex and highly dynamic lateral structure; and changes in lipid density and fluidity are believed to play an essential role in membrane targeting and function. The dynamic structure of liquids on the molecular scale can exhibit complex transient density fluctuations. Here the lateral heterogeneity of lipid dynamics is explored in free standing lipid monolayers. As the temperature is lowered the probes exhibit increasingly broad and heterogeneous rotational correlation. This increase in heterogeneity appears to exhibit a critical onset, similar to those observed for glass forming fluids. We explore heterogeneous relaxation in in a single constituent lipid monolayer of 1, 2-dimyristoyl-sn-glycero-3-phosphocholine by measuring the rotational diffusion of a fluorescent probe (1-palmitoyl-2-[1]-sn-glycero-3-phosphocholine), which is embedded in the lipid monolayer at low labeling density. Dynamic distributions are measured using wide-field time-resolved fluorescence anisotropy. The observed relaxation exhibits a narrow, liquid-like distribution at high temperatures (τ ˜ 2.4 ns), consistent with previous experimental measures (Dadashvand et al 2014 Struct. Dyn. 1 054701, Loura and Ramalho 2007 Biochim. Biophys. Acta 1768 467-478). However, as the temperature is quenched, the distribution broadens, and we observe the appearance of a long relaxation population (τ ˜ 16.5 ns). This supports the heterogeneity observed for lipids at high packing densities, and demonstrates that the nanoscale diffusion and reorganization in lipid structures can be significantly complex, even in the simplest amorphous architectures. Dynamical heterogeneity of this form can have a significant impact on the organization, permeability and energetics of lipid membrane structures.

  12. Quality by Design (QbD)-enabled development of aceclofenac loaded-nano structured lipid carriers (NLCs): An improved dermatokinetic profile for inflammatory disorder(s).

    Science.gov (United States)

    Garg, Neeraj K; Sharma, Gajanand; Singh, Bhupinder; Nirbhavane, Pradip; Tyagi, Rajeev K; Shukla, Rahul; Katare, O P

    2017-01-30

    Present study was designed to prepare and characterize aceclofenac loaded nanostructured lipid carriers (NLCs) employing Quality by Design (QbD)-oriented approach. The NLCs were evaluated for their transdermal penetration potential and stability. Aceclofenac loaded nanostructured lipid carriers (NLCs) were prepared & characterized, by employing Quality by Design (QbD)-oriented approach and further evaluated for transdermal penetration potential and stability. Different lipids and surfactants were chosen to prepare NLCs using microemulsion method as critical material attributes (CMAs). A 3(3) factorial design was used for optimization of NLCs, and evaluating them for different critical quality attributes (CQAs), viz. particle size, polydispersity index (PDI), zeta potential, in vitro drug release, entrapment efficiency. The effect of CMAs such as lipids, oil: lipid ratio and concentration of surfactants on CQAs viz. drug entrapment efficiency and particle size were systematically evaluated to optimize NLCs. The optimized NLCs were further incorporated into carbopol gel and characterized for texture and rheology profile followed by in vitro and in vivo evaluations. The optimized ACE-NLCs were found to be spherical, nanometric in size with higher drug loading and entrapment efficiency. Results of the in vitro drug release study showed that the developed formulation followed Korsmeyer-Peppas model showing Fickian diffusion. The release was biphasic i.e., initial burst release followed by sustained drug release upto 48h. The optimized NLCs-based gel formulation showed superior texture, rheological profile and showed better cell uptake efficiency on hyperkeratinocytic cells (HaCaT cell lines) with higher ex vivo skin permeability efficiency vis-à-vis marketed formulation. In conclusion, dermatokinetic modeling and pharmacodynamic study using carrageenan induced edema mice suggests that aceclofenac loaded NLCs hydrogel may provide a better delivery alternative to target

  13. Lipides polaires marins

    Directory of Open Access Journals (Sweden)

    Fanni Jacques

    2004-03-01

    Full Text Available Les lipides polaires marins, notamment les phospholipides (PL, retiennent depuis quelques années l’attention des chercheurs et des industriels en raison de leur composition, particulièrement riche en acides gras polyinsaturés à longue chaîne (AGPI-LC. Ils combinent ainsi les propriétés reconnues des AGPI-LC à l’intérêt métabolique et structural des phospholipides. Les sources sont nombreuses et d’accès très diversifié. Le défi industriel provient de leurs caractéristiques amphiphiles et aromatiques particulièrement marquées qui rend leur extraction très difficile.

  14. Structure and dynamics of H2O vis-á-vis phenylalanine recognition at a DPPC lipid membrane via interfacial H-bond types: Insights from polarized FT-IRRAS and ADMP simulations

    Science.gov (United States)

    Sarangi, Nirod Kumar; Ramesh, Nivarthi; Patnaik, Archita

    2015-01-01

    Preferential and enantioselective interactions of l-/d-Phenylalanine (l-Phe and d-Phe) and butoxycarbonyl-protected l-/d-Phenylalanine (LPA and DPA) as guest with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (l-DPPC) as host were tapped by using real time Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS). Polarization-modulated FT-IRRAS of DPPC monolayers above the phenylalanine modified subphases depicted fine structure/conformation differences under considerations of controlled 2D surface pressure. Selective molecular recognition of d-enantiomer over l-enantiomer driven by the DPPC head group via H-bonding and electrostatic interactions was evident spectroscopically. Accordingly, binding constants (K) of 145, 346, 28, and 56 M-1 for LPA, DPA, l-Phe, and d-Phe, respectively, were estimated. The real time FT-IRRAS water bands were strictly conformation sensitive. The effect of micro-solvation on the structure and stability of the 1:1 diastereomeric l-lipid⋯, LPA/DPA and l-lipid⋯, (l/d)-Phe adducts was investigated with the aid of Atom-centered Density Matrix Propagation (ADMP), a first principle quantum mechanical molecular dynamics approach. The phosphodiester fragment was the primary site of hydration where specific solvent interactions were simulated through single- and triple- "water-phosphate" interactions, as water cluster's "tetrahedral dice" to a "trimeric motif" transformation as a partial de-clusterization was evident. Under all the hydration patterns considered in both static and dynamic descriptions of density functional theory, l-lipid/d-amino acid enantiomer adducts continued to be stable structures while in dynamic systems, water rearranged without getting "squeezed-out" in the process of recognition. In spite of the challenging computational realm of this multiscale problem, the ADMP simulated molecular interactions complying with polarized vibrational spectroscopy unraveled a novel route to chiral recognition and

  15. LipidHome: a database of theoretical lipids optimized for high throughput mass spectrometry lipidomics.

    Directory of Open Access Journals (Sweden)

    Joseph M Foster

    Full Text Available Protein sequence databases are the pillar upon which modern proteomics is supported, representing a stable reference space of predicted and validated proteins. One example of such resources is UniProt, enriched with both expertly curated and automatic annotations. Taken largely for granted, similar mature resources such as UniProt are not available yet in some other "omics" fields, lipidomics being one of them. While having a seasoned community of wet lab scientists, lipidomics lies significantly behind proteomics in the adoption of data standards and other core bioinformatics concepts. This work aims to reduce the gap by developing an equivalent resource to UniProt called 'LipidHome', providing theoretically generated lipid molecules and useful metadata. Using the 'FASTLipid' Java library, a database was populated with theoretical lipids, generated from a set of community agreed upon chemical bounds. In parallel, a web application was developed to present the information and provide computational access via a web service. Designed specifically to accommodate high throughput mass spectrometry based approaches, lipids are organised into a hierarchy that reflects the variety in the structural resolution of lipid identifications. Additionally, cross-references to other lipid related resources and papers that cite specific lipids were used to annotate lipid records. The web application encompasses a browser for viewing lipid records and a 'tools' section where an MS1 search engine is currently implemented. LipidHome can be accessed at http://www.ebi.ac.uk/apweiler-srv/lipidhome.

  16. The differential protein and lipid compositions of noncaveolar lipid microdomains and caveolae

    Institute of Scientific and Technical Information of China (English)

    Yao Yao; Shangyu Hong; Hu Zhou; Taichang Yuan; Rong Zeng; Kan Liao

    2009-01-01

    Morphologically, caveolae and lipid rafts are two different membrane structures. They are often reported to share similar lipid and protein compositions, and are considered to be two subtypes of membrane lipid microdomains. By modifying sucrose density gradient flotation centrifugation, which is used to isolate lipid microdomains, we were able to separate caveolae and noncaveolar lipid microdomains into two distinct fractions. The caveolar membranes are membrane vesicles of 100-nm diameter, enriched with caveolin-1 and flotillin-1. The noncaveolar lipid microdomains are amorphous membranes and most likely the coalescence of heterogeneous lipid rafts. They are depleted of caveolin-1 and are more enriched with cholesterol and sphingolipids than the caveolae. Many membrane proteins, such as insulin-like growth factor-1 receptor (membrane receptor), aquaporin-1 (membrane transporter), Thy-1 and N-cadherin (glycosylphosphatidylinositol-anchored membrane protein and membrane glycoprotein), are specifically associated with noncaveolar lipid microdomains, but not with caveolae. These results indicate that the lipid and protein compositions of caveolae differ from those of noncaveolar lipid microdomains. The difference in their protein compositions implies that these two membrane microdomains may have different cellular functions.

  17. DNA release from lipoplexes by anionic lipids: correlation with lipid mesomorphism, interfacial curvature, and membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Tarahovsky, Yury S.; Koynova, Rumiana; MacDonald, Robert C. (Northwestern)

    2010-01-18

    DNA release from lipoplexes is an essential step during lipofection and is probably a result of charge neutralization by cellular anionic lipids. As a model system to test this possibility, fluorescence resonance energy transfer between DNA and lipid covalently labeled with Cy3 and BODIPY, respectively, was used to monitor the release of DNA from lipid surfaces induced by anionic liposomes. The separation of DNA from lipid measured this way was considerably slower and less complete than that estimated with noncovalently labeled DNA, and depends on the lipid composition of both lipoplexes and anionic liposomes. This result was confirmed by centrifugal separation of released DNA and lipid. X-ray diffraction revealed a clear correlation of the DNA release capacity of the anionic lipids with the interfacial curvature of the mesomorphic structures developed when the anionic and cationic liposomes were mixed. DNA release also correlated with the rate of fusion of anionic liposomes with lipoplexes. It is concluded that the tendency to fuse and the phase preference of the mixed lipid membranes are key factors for the rate and extent of DNA release. The approach presented emphasizes the importance of the lipid composition of both lipoplexes and target membranes and suggests optimal transfection may be obtained by tailoring lipoplex composition to the lipid composition of target cells.

  18. 脂分子对整合膜蛋白结构与功能的影响%How Do Lipids Affect the Structure and Function of Integral Membrane Proteins

    Institute of Scientific and Technical Information of China (English)

    衡杰; 吴岩; 王先平; 张凯

    2012-01-01

    In living cells, integral membrane protein (IMPs) and lipid bilayer compose a complex and dynamic entirety. The lipid surrounding membrane proteins is called non-annular lipid. In contrast, lipid molecules, that bound tightly to transmembrane α-helices or at protein-protein interfaces by hydrophobic bond and electrostatic interaction are called non-annular lipid. There are some non-annular sites at IMPs that the hydrophobic molecules can bind and regulate the target proteins function. During co-evolution between IMPs and lipids, some important interactions are preserved. Some general principals about chemical interaction between non-annular lipids and IMPs have been proposed. For instance, lipid head groups often interact with polar amino acid residues via ion pairs and hydrogen bonds. Understanding lipids and IMPs interaction will not only facilitate membrane protein structural study but also provide us a more complete picture of the cellular metabolic regulation.%生物体内,整合膜蛋白镶嵌在磷脂双分子层中,与膜脂分子形成一个动态的复合物.包裹在整合膜蛋白周围的脂类分子通常称为环形脂分子,而另一类脂分子通过氢键、疏水作用和静电力结合在整合膜蛋白的跨膜螺旋之间或膜蛋白复合物亚基间的界面上,这些分子被称为非环形脂分子.整合膜蛋白表面与非环形脂作用的位点称为非环形位点,是蛋白活性调控的重要位置.非环形位点对于分析细胞如何通过疏水分子实现对整合膜蛋白结构和功能的精确调节作用具有普遍意义.膜脂分子与整合膜蛋白的长期共进化,使二者间的化学相互作用具有一些明显的特征.例如,脂分子头部附近,常常有两个甚至更多的氨基酸残基与其形成氢键,这些氨基酸残基通常采用一个带正电的残基与一个极性残基的组合方式;Trp和Tyr常出现在脂相-水相的界面上,便于与脂分子形成范德华力相互作用,这为整

  19. Signature lipid biomarkers for in situ microbial biomass, community structure and nutritional status of deep subsurface microbiota in relation to geochemical gradients. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    White, D.C.; Ringelberg, D.B.

    1998-02-01

    To obtain a better understanding of the microbial ecology of the deep subsurface, it was necessary to employ alternate techniques for the identification of microorganisms in situ. Classical microbiological techniques assay only those organisms which are culturable with bias occurring towards the media selected. Since culturable microorganisms typically represents only 0.1 to 10% of the extant microbiota, techniques for the direct assay of microorganisms in situ were needed. The analysis of cellular lipid biomarkers is a technique whereby microbial communities can be assayed directly in a variety of environmental matrices. Through the quantitative recovery of lipid biomarkers, estimations of cell biomass, community composition and community nutritional and/or physiological status can be obtained.

  20. Cell Adhesion Induced Using Surface Modification with Cell-Penetrating Peptide-Conjugated Poly(ethylene glycol)-Lipid: A New Cell Glue for 3D Cell-Based Structures.

    Science.gov (United States)

    Teramura, Yuji; Asif, Sana; Ekdahl, Kristina N; Gustafson, Elisabet; Nilsson, Bo

    2017-01-11

    We synthesized a novel material, cell-penetrating peptide-conjugated poly(ethylene glycol)-lipid (CPP-PEG-lipid), that can induce the adhesion of floating cells. Firm cell adhesion with spreading could be induced by cell surface modification with the CPP-PEG-lipids. Cell adhesion was induced by CPPs but not by any other cationic short peptides we tested. Here, we demonstrated adherence using the floating cell line CCRF-CEM as well as primary human T cells, B cells, erythrocytes, and hepatocytes. As compared to cells grown in suspension, adherent cells were more rapidly induced to attach to substrates with the cell-surface modification. The critical factor for attachment was localization of CPPs at the cell membrane by PEG-lipids with PEG > 20 kDa. These cationic CPPs on PEG chains were able to interact with substrate surfaces such as polystyrene (PS) surfaces, glass surfaces, and PS microfibers that are negatively charged, inducing firm cell adhesion and cell spreading. Also, as opposed to normal cationic peptides that interact strongly with cell membranes, CPPs were less interactive with the cell surfaces because of their cell-penetrating property, making them more available for adhering cells to the substrate surface. No effects on cell viability or cell proliferation were observed after the induction of cell adhesion. With this technique, cells could be easily immobilized onto PS microfibers, an important step in fabricating 3D cell-based structures. Cells immobilized onto 3D PS microfibers were alive, and human hepatocytes showed normal production of urea and albumin on the microfibers. This method is novel in inducing firm cell adhesion via a one-step treatment.

  1. The emerging roles of lipids in circadian control.

    Science.gov (United States)

    Adamovich, Yaarit; Aviram, Rona; Asher, Gad

    2015-08-01

    Lipids play vital roles in a wide variety of cellular functions. They act as structural components in cell membranes, serve as a major form of energy storage, and function as key signaling molecules. Mounting evidence points towards a tight interplay between lipids and circadian clocks. In mammals, circadian clocks regulate the daily physiology and metabolism, and disruption of circadian rhythmicity is associated with altered lipid homeostasis and pathologies such as fatty liver and obesity. Concomitantly, emerging evidence suggest that lipids are embedded within the core clock circuitry and participate in circadian control. Recent advances in lipidomics methodologies and their application in chronobiology studies have shed new light on the cross talk between circadian clocks and lipid homeostasis. We review herein the latest literature related to the involvement of lipids in circadian clock's function and highlight the contribution of circadian lipidomics studies to our understanding of circadian rhythmicity and lipid homeostasis. This article is part of a Special Issue entitled Brain Lipids.

  2. Cloning, structural characterization and expression analysis of a novel lipid storage droplet protein-1 (LSD-1) gene in Chinese honeybee (Apis cerana cerana).

    Science.gov (United States)

    Liu, Li; Gong, Zhihong; Guo, Xingqi; Xu, Baohua

    2012-03-01

    Lipid storage droplet 1 (LSD-1), a PAT family protein located around lipid droplets in insects, is intimately linked to lipid droplets formation and lipid metabolism. Conjugated linoleic acid (CLA) and rosiglitazone (Rosi) have previously been shown to modulate the expression of several PAT family proteins through peroxisome proliferator-activated receptor-γ (PPARγ). In the present study, we isolated and characterized a novel LSD-1 gene, referred to AccLSD-1, from Chinese honeybee (Apis cerana cerana). Sequence analysis indicated that the central region of LSD-1 protein had significant sequence similarity and a typical LSD-1 gene was composed of 8 exons and 7 introns. Interestingly, the first intron of AccLSD-1 including several PPARγ-response elements (PPREs) was located in 5' UTR. Analysis of 5'-flanking region of AccLSD-1 revealed a number of putative cis-acting elements, including three PPREs. Quantitative real-time PCR showed that AccLSD-1 expressed ubiquitously from feeding larva to adult, and its expression level was highest at brown-eyed pupae (Pb) stage. The effect of CLA, Rosi and combination on AccLSD-1 expressions indicated 1% CLA and 0.5 mg/ml Rosi were considered as the suitable diets for rearing adult workers in laboratory, and AccLSD-1 was down-regulated by CLA whereas up-regulated by Rosi. Furthermore, the combination of CLA and Rosi remarkly rescued the suppression of AccLSD-1 expression by CLA alone. These results suggest that AccLSD-1 is associated with A. cerana cerana development, especially during pupal metamorphosis, and can be regulated by CLA or Rosi possibly via activating PPARγ.

  3. Chemically Stable Lipids for Membrane Protein Crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Ishchenko, Andrii; Peng, Lingling; Zinovev, Egor; Vlasov, Alexey; Lee, Sung Chang; Kuklin, Alexander; Mishin, Alexey; Borshchevskiy, Valentin; Zhang, Qinghai; Cherezov, Vadim (MIPT); (USC); (Scripps)

    2017-05-01

    The lipidic cubic phase (LCP) has been widely recognized as a promising membrane-mimicking matrix for biophysical studies of membrane proteins and their crystallization in a lipidic environment. Application of this material to a wide variety of membrane proteins, however, is hindered due to a limited number of available host lipids, mostly monoacylglycerols (MAGs). Here, we designed, synthesized, and characterized a series of chemically stable lipids resistant to hydrolysis, with properties complementary to the widely used MAGs. In order to assess their potential to serve as host lipids for crystallization, we characterized the phase properties and lattice parameters of mesophases made of two most promising lipids at a variety of different conditions by polarized light microscopy and small-angle X-ray scattering. Both lipids showed remarkable chemical stability and an extended LCP region in the phase diagram covering a wide range of temperatures down to 4 °C. One of these lipids has been used for crystallization and structure determination of a prototypical membrane protein bacteriorhodopsin at 4 and 20 °C.

  4. Topologies, structures and parameter files for lipid simulations in GROMACS with the OPLS-aa force field: DPPC, POPC, DOPC, PEPC, and cholesterol

    Directory of Open Access Journals (Sweden)

    Waldemar Kulig

    2015-12-01

    Full Text Available In this data article we provide topologies and force field parameters files for molecular dynamics simulations of lipids in the OPLS-aa force field using the GROMACS package. This is the first systematic parameterization of lipid molecules in this force field. Topologies are provided for four phosphatidylcholines: saturated DPPC, mono-cis unsaturated POPC and DOPC, and mono-trans unsaturated PEPC. Parameterization of the phosphatidylcholines was achieved in two steps: first, we supplemented the OPLS force field parameters for DPPC with new parameters for torsion angles and van der Waals parameters for the carbon and hydrogen atoms in the acyl chains, as well as new partial atomic charges and parameters for torsion angles in the phosphatidylcholine and glycerol moieties [1]. Next, we derived parameters for the cis and trans double bonds and the neighboring them single bonds [2]. Additionally, we provide GROMACS input files with parameters describing simulation conditions (md.mdp, which are strongly recommended to be used with these lipids models. The data are associated with the research article “Cis and trans unsaturated phosphatidylcholine bilayers: a molecular dynamics simulation study” [2] and provided as supporting materials.

  5. Direct visualization of lipid domains in human skin stratum corneum's lipid membranes

    DEFF Research Database (Denmark)

    Plasencia, I; Norlen, Lars; Bagatolli, Luis

    2007-01-01

    ; and iii), whether pH has a direct effect on the lipid matrix phase behavior. In this work the lateral structure of membranes composed of lipids extracted from human skin stratum corneum was studied in a broad temperature range (10 degrees C-90 degrees C) using different techniques such as differential......The main function of skin is to serve as a physical barrier between the body and the environment. This barrier capacity is in turn a function of the physical state and structural organization of the stratum corneum extracellular lipid matrix. This lipid matrix is essentially composed of very long...... scanning calorimetry, fluorescence spectroscopy, and two-photon excitation and laser scanning confocal fluorescence microscopy. Here we show that hydrated bilayers of human skin stratum corneum lipids express a giant sponge-like morphology with dimensions corresponding to the global three...

  6. Extraction, chromatographic and mass spectrometric methods for lipid analysis.

    Science.gov (United States)

    Pati, Sumitra; Nie, Ben; Arnold, Robert D; Cummings, Brian S

    2016-05-01

    Lipids make up a diverse subset of biomolecules that are responsible for mediating a variety of structural and functional properties as well as modulating cellular functions such as trafficking, regulation of membrane proteins and subcellular compartmentalization. In particular, phospholipids are the main constituents of biological membranes and play major roles in cellular processes like transmembrane signaling and structural dynamics. The chemical and structural variety of lipids makes analysis using a single experimental approach quite challenging. Research in the field relies on the use of multiple techniques to detect and quantify components of cellular lipidomes as well as determine structural features and cellular organization. Understanding these features can allow researchers to elucidate the biochemical mechanisms by which lipid-lipid and/or lipid-protein interactions take place within the conditions of study. Herein, we provide an overview of essential methods for the examination of lipids, including extraction methods, chromatographic techniques and approaches for mass spectrometric analysis.

  7. Lipid droplet mobilization: The different ways to loosen the purse strings.

    Science.gov (United States)

    D'Andrea, Sabine

    2016-01-01

    Cytosolic lipid droplets are dynamic lipid-storage organelles that play a crucial role as reservoirs of metabolic energy and membrane precursors. These organelles are present in virtually all cell types, from unicellular to pluricellular organisms. Despite similar structural organization, lipid droplets are heterogeneous in morphology, distribution and composition. The protein repertoire associated to lipid droplet controls the organelle dynamics. Distinct structural lipid droplet proteins are associated to specific lipolytic pathways. The role of these structural lipid droplet-associated proteins in the control of lipid droplet degradation and lipid store mobilization is discussed. The control of the strictly-regulated lipolysis in lipid-storing tissues is compared between mammals and plants. Differences in the cellular regulation of lipolysis between lipid-storing tissues and other cell types are also discussed.

  8. α-Synuclein senses lipid packing defects and induces lateral expansion of lipids leading to membrane remodeling.

    Science.gov (United States)

    Ouberai, Myriam M; Wang, Juan; Swann, Marcus J; Galvagnion, Celine; Guilliams, Tim; Dobson, Christopher M; Welland, Mark E

    2013-07-19

    There is increasing evidence for the involvement of lipid membranes in both the functional and pathological properties of α-synuclein (α-Syn). Despite many investigations to characterize the binding of α-Syn to membranes, there is still a lack of understanding of the binding mode linking the properties of lipid membranes to α-Syn insertion into these dynamic structures. Using a combination of an optical biosensing technique and in situ atomic force microscopy, we show that the binding strength of α-Syn is related to the specificity of the lipid environment (the lipid chemistry and steric properties within a bilayer structure) and to the ability of the membranes to accommodate and remodel upon the interaction of α-Syn with lipid membranes. We show that this interaction results in the insertion of α-Syn into the region of the headgroups, inducing a lateral expansion of lipid molecules that can progress to further bilayer remodeling, such as membrane thinning and expansion of lipids out of the membrane plane. We provide new insights into the affinity of α-Syn for lipid packing defects found in vesicles of high curvature and in planar membranes with cone-shaped lipids and suggest a comprehensive model of the interaction between α-Syn and lipid bilayers. The ability of α-Syn to sense lipid packing defects and to remodel membrane structure supports its proposed role in vesicle trafficking.

  9. Lipid Rafts: Keys to Sperm Maturation, Fertilization, and Early Embryogenesis

    Directory of Open Access Journals (Sweden)

    Natsuko Kawano

    2011-01-01

    Full Text Available Cell membranes are composed of many different lipids and protein receptors, which are important for regulating intracellular functions and cell signaling. To orchestrate these activities, the cell membrane is compartmentalized into microdomains that are stably or transiently formed. These compartments are called “lipid rafts”. In gamete cells that lack gene transcription, distribution of lipids and proteins on these lipid rafts is focused during changes in their structure and functions such as starting flagella movement and membrane fusion. In this paper, we describe the role of lipid rafts in gamete maturation, fertilization, and early embryogenesis.

  10. Detection of Lipid Induced Structural Changes of the Marburg Virus Matrix Protein VP40 Using Hydrogen/Deuterium Exchange Mass Spectrometry.

    Science.gov (United States)

    Wijesinghe, Kaveesha J; Urata, Sarah; Bhattarai, Nisha; Kooijman, Edgar E; Gerstman, Bernard S; Chapagain, Prem P; Li, Sheng; Stahelin, Robert V

    2017-02-06

    Marburg virus (MARV) is a lipid-enveloped virus from the Filoviridae family containing a negative sense RNA genome. One of the seven MARV genes encodes the matrix protein VP40, which forms a matrix layer beneath the plasma membrane inner leaflet to facilitate budding from the host cell. MARV VP40 (mVP40) has been shown to be a dimeric peripheral protein with a broad and flat basic surface that can associate with anionic phospholipids such as phosphatidylserine. While a number of mVP40 cationic residues have been shown to facilitate binding to membranes containing anionic lipids, much less is known on how mVP40 assembles to form the matrix layer following membrane binding. Here we have used hydrogen-deuterium exchange (H/DX) mass spectrometry to determine the solvent accessibility of mVP40 residues in the absence and presence of phosphatidylserine and phosphatidylinositol-4,5-bisphosphate. H/DX analysis demonstrates two basic loops in the mVP40 C-terminal domain make important contributions to anionic membrane binding and also revealed a potential oligomerization interface in the C-terminal domain as well as a conserved oligomerization interface in the mVP40 N-terminal domain. Lipid binding assays confirm the role of the two basic patches elucidated with HD/X measurements while molecular dynamics simulations and membrane insertion measurements complement these studies to demonstrate mVP40 doesn't appreciably insert into the hydrocarbon region of anionic membranes in contrast to the matrix protein from Ebola virus. Taken together, we propose a model by which association of the mVP40 dimer with the anionic plasma membrane facilitates assembly of mVP40 oligomers.

  11. Channel protein engineering: Synthetic 22-mer peptide from the primary structure of the voltage-sensitive sodium channel forms ionic channels in lipid bilayers

    OpenAIRE

    1988-01-01

    A synthetic 22-mer peptide that mimics the sequence of a putative pore segment of the voltage-dependent sodium channel forms transmembrane ionic channels in lipid bilayers. Several features of the authentic sodium channel are exhibited by the synthetic peptide: (i) The single channel conductance of the most frequent event is 20 pS in 0.5 M NaCl. (ii) The single channel open and closed lifetimes are in the ms time range. (iii) The synthetic channel discriminates cations over anions but is nons...

  12. Alkyl ether lipids, ion channels and lipid raft reorganization in cancer therapy.

    Science.gov (United States)

    Jaffrès, Paul-Alain; Gajate, Consuelo; Bouchet, Ana Maria; Couthon-Gourvès, Hélène; Chantôme, Aurélie; Potier-Cartereau, Marie; Besson, Pierre; Bougnoux, Philippe; Mollinedo, Faustino; Vandier, Christophe

    2016-09-01

    Synthetic alkyl lipids, such as the ether lipids edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) and ohmline (1-O-hexadecyl-2-O-methyl-rac-glycero-3-β-lactose), are forming a class of antitumor agents that target cell membranes to induce apoptosis and to decrease cell migration/invasion, leading to the inhibition of tumor and metastasis development. In this review, we present the structure-activity relationship of edelfosine and ohmline, and we point out differences and similarities between these two amphiphilic compounds. We also discuss the mechanisms of action of these synthetic alkyl ether lipids (involving, among other structures and molecules, membrane domains, Fas/CD95 death receptor signaling, and ion channels), and highlight a key role for lipid rafts in the underlying process. The reorganization of lipid raft membrane domains induced by these alkyl lipids affects the function of death receptors and ion channels, thus leading to apoptosis and/or inhibition of cancer cell migration. The possible therapeutic use of these alkyl lipids and the clinical perspectives for these lipids in prevention or/and treatment of tumor development and metastasis are also discussed.

  13. Structural relationship of the lipid A acyl groups to activation of murine Toll-like receptor 4 by lipopolysaccharides from pathogenic strains of Burkholderia mallei, Acinetobacter baumannii and Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Kirill V Korneev

    2015-11-01

    Full Text Available Toll-like receptor 4 (TLR4 is required for activation of innate immunity upon recognition of lipopolysaccharide (LPS of Gram-negative bacteria. The ability of TLR4 to respond to a particular LPS species is important since insufficient activation may not prevent bacterial growth while excessive immune reaction may lead to immunopathology associated with sepsis. Here we investigated the biological activity of LPS from Burkholderia mallei that causes glanders, and from the two well-known opportunistic pathogens Acinetobacter baumannii and Pseudomonas aeruginosa (causative agents of nosocomial infections. For each bacterial strain, R-form LPS preparations were purified by hydrophobic chromatography and the chemical structure of lipid A, an LPS structural component, was elucidated by HR-MALDI-TOF mass spectrometry. The biological activity of LPS samples was evaluated by their ability to induce production of proinflammatory cytokines, such as IL-6 and TNF, by bone marrow-derived macrophages (BMDM. Our results demonstrate direct correlation between the biological activity of LPS from these pathogenic bacteria and the extent of their lipid A acylation.

  14. Structural Relationship of the Lipid A Acyl Groups to Activation of Murine Toll-Like Receptor 4 by Lipopolysaccharides from Pathogenic Strains of Burkholderia mallei, Acinetobacter baumannii, and Pseudomonas aeruginosa

    Science.gov (United States)

    Korneev, Kirill V.; Arbatsky, Nikolay P.; Molinaro, Antonio; Palmigiano, Angelo; Shaikhutdinova, Rima Z.; Shneider, Mikhail M.; Pier, Gerald B.; Kondakova, Anna N.; Sviriaeva, Ekaterina N.; Sturiale, Luisa; Garozzo, Domenico; Kruglov, Andrey A.; Nedospasov, Sergei A.; Drutskaya, Marina S.; Knirel, Yuriy A.; Kuprash, Dmitry V.

    2015-01-01

    Toll-like receptor 4 (TLR4) is required for activation of innate immunity upon recognition of lipopolysaccharide (LPS) of Gram-negative bacteria. The ability of TLR4 to respond to a particular LPS species is important since insufficient activation may not prevent bacterial growth while excessive immune reaction may lead to immunopathology associated with sepsis. Here, we investigated the biological activity of LPS from Burkholderia mallei that causes glanders, and from the two well-known opportunistic pathogens Acinetobacter baumannii and Pseudomonas aeruginosa (causative agents of nosocomial infections). For each bacterial strain, R-form LPS preparations were purified by hydrophobic chromatography and the chemical structure of lipid A, an LPS structural component, was elucidated by HR-MALDI-TOF mass spectrometry. The biological activity of LPS samples was evaluated by their ability to induce production of proinflammatory cytokines, such as IL-6 and TNF, by bone marrow-derived macrophages. Our results demonstrate direct correlation between the biological activity of LPS from these pathogenic bacteria and the extent of their lipid A acylation. PMID:26635809

  15. Structural lipid changes and Na(+)/K(+)-ATPase activity of gill cells' basolateral membranes during saltwater acclimation in sea lamprey (Petromyzon marinus, L.) juveniles.

    Science.gov (United States)

    Lança, Maria João; Machado, Maria; Ferreira, Ana Filipa; Quintella, Bernardo Ruivo; de Almeida, Pedro Raposo

    2015-11-01

    Seawater acclimation is a critical period for anadromous species and a process yet to be understood in lampreys. Considering that changes in lipid composition of the gill cells' basolateral membranes may disrupt the major transporter Na(+)K(+)-ATPase, the goal of this study was to detect changes at this level during juvenile sea lamprey seawater acclimation. The results showed that saltwater acclimation has a direct effect on the fatty acid composition of gill cells basolateral membrane's phospholipids. When held in full-strength seawater, the fatty acid profile of basolateral membrane's phospholipids suffered a restructure by increasing either saturation or the ratio between oleic acid and eicosapentaenoic acid. Simultaneously, the activity of Na(+)K(+)-ATPase revealed a significant and positive correlation with basolateral membrane's cholesterol content in the presence of highest salinity. Our results pointed out for lipid adjustments involving the functional transporter present on the gill cell basolateral membranes to ensure the role played by branchial Na(+)K(+)-ATPase in ion transport during saltwater acclimation process. The responses observed contributed to the strategy adopted by gill cell's basolateral membranes to compensate for osmotic and ionic stressors, to ensure the success of the process of seawater acclimation associated with the downstream trophic migration of juvenile sea lamprey.

  16. Phospholipid oxidation generates potent anti-inflammatory lipid mediators that mimic structurally related pro-resolving eicosanoids by activating Nrf2.

    Science.gov (United States)

    Bretscher, Peter; Egger, Julian; Shamshiev, Abdijapar; Trötzmüller, Martin; Köfeler, Harald; Carreira, Erick M; Kopf, Manfred; Freigang, Stefan

    2015-05-01

    Exposure of biological membranes to reactive oxygen species creates a complex mixture of distinct oxidized phospholipid (OxPL) species, which contribute to the development of chronic inflammatory diseases and metabolic disorders. While the ability of OxPL to modulate biological processes is increasingly recognized, the nature of the biologically active OxPL species and the molecular mechanisms underlying their signaling remain largely unknown. We have employed a combination of mass spectrometry, synthetic chemistry, and immunobiology approaches to characterize the OxPL generated from the abundant phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) and investigated their bioactivities and signaling pathways in vitro and in vivo. Our study defines epoxycyclopentenones as potent anti-inflammatory lipid mediators that mimic the signaling of endogenous, pro-resolving prostanoids by activating the transcription factor nuclear factor E2-related factor 2 (Nrf2). Using a library of OxPL variants, we identified a synthetic OxPL derivative, which alleviated endotoxin-induced lung injury and inhibited development of pro-inflammatory T helper (Th) 1 cells. These findings provide a molecular basis for the negative regulation of inflammation by lipid peroxidation products and propose a novel class of highly bioactive compounds for the treatment of inflammatory diseases.

  17. Lipid-lipid and lipid-drug interactions in biological membranes

    Science.gov (United States)

    Martynowycz, Michael W.

    Interactions between lipids and drug molecules in biological membranes help govern proper biological function in organisms. The mechanisms responsible for hydrophobic drug permeation remain elusive. Many small molecule drugs are hydrophobic. These drugs inhibit proteins in the cellular interior. The rise of antibiotic resistance in bacteria is thought to be caused by mutations in protein structure, changing drug kinetics to favor growth. However, small molecule drugs have been shown to have different mechanisms depending in the structure of the lipid membrane of the target cell. Biological membranes are investigated using Langmuir monolayers at the air-liquid interface. These offer the highest level of control in the mimetic system and allow them to be investigated using complementary techniques. Langmuir isotherms and insertion assays are used to determine the area occupied by each lipid in the membrane and the change in area caused by the introduction of a drug molecule, respectively. Specular X-ray reflectivity is used to determine the electron density of the monolayer, and grazing incidence X-ray diffraction is used to determine the in-plane order of the monolayer. These methods determine the affinity of the drug and the mechanism of action. Studies are presented on hydrophobic drugs with mammalian membrane mimics using warfarin along with modified analogues, called superwarfarins. Data shows that toxicity of these modified drugs are modulated by the membrane cholesterol content in cells; explaining several previously unexplained effects of the drugs. Membrane mimics of bacteria are investigated along with their interactions with a hydrophobic antibiotic, novobiocin. Data suggests that permeation of the drug is mediated by modifications to the membrane lipids, and completely ceases translocation under certain circumstances. Circumventing deficiencies in small, hydrophobic drugs is approached by using biologically mimetic oligomers. Peptoids, mimetic of host

  18. Studying lipid-protein interactions with electron paramagnetic resonance spectroscopy of spin-labeled lipids.

    Science.gov (United States)

    Páli, Tibor; Kóta, Zoltán

    2013-01-01

    Spin label electron paramagnetic resonance (EPR) of lipid-protein interactions reveals crucial features of the structure and assembly of integral membrane proteins. Spin label EPR spectroscopy is the technique of choice to characterize the protein-solvating lipid shell in its highly dynamic nature, because the EPR spectra of lipids that are spin labeled close to the terminal methyl end of their acyl chains display two spectral components, those corresponding to lipids directly contacting the protein and those corresponding to lipids in the bulk fluid bilayer regions of the membrane. In this chapter, typical spin label EPR procedures are presented that allow determination of the stoichiometry of interaction of spin-labeled lipids with the intra-membranous region of membrane proteins or polypeptides, as well as the association constant of the spin-labeled lipid with respect to the host lipid. The lipids giving rise to the so-called immobile spectral component in the EPR spectrum of such samples are identified as the motionally restricted first-shell lipids solvating membrane proteins in biomembranes. Stoichiometry and selectivity are directly related to the structure of the intra-membranous sections of membrane-associated proteins or polypeptides and can be used to study the state of assembly of such proteins in the membrane. Since these characteristics of lipid-protein interactions are discussed in detail in the literature [see Marsh (Eur Biophys J 39:513-525, 2010) for a most recent review], here we focus more on how to spin label model and biomembranes and how to measure and analyze the two-component EPR spectra of spin-labeled lipids in phospholipid bilayers that contain proteins or polypeptides. After a description of how to prepare spin-labeled model and native biological membranes, we present the reader with computational procedures for determining the molar fraction of motionally restricted lipids when both, one, or none of the pure isolated-mobile or

  19. Ionization behavior of amino lipids for siRNA delivery: determination of ionization constants, SAR, and the impact of lipid pKa on cationic lipid-biomembrane interactions.

    Science.gov (United States)

    Zhang, Jingtao; Fan, Haihong; Levorse, Dorothy A; Crocker, Louis S

    2011-03-01

    Ionizable amino lipids are being pursued as an important class of materials for delivering small interfering RNA (siRNA) therapeutics, and research is being conducted to elucidate the structure-activity relationships (SAR) of these lipids. The pK(a) of cationic lipid headgroups is one of the critical physiochemical properties of interest due to the strong impact of lipid ionization on the assembly and performance of these lipids. This research focused on developing approaches that permit the rapid determination of the relevant pK(a) of the ionizable amino lipids. Two distinct approaches were investigated: (1) potentiometric titration of amino lipids dissolved in neutral surfactant micelles; and (2) pH-dependent partitioning of a fluorescent dye to cationic liposomes formulated from amino lipids. Using the approaches developed here, the pK(a) values of cationic lipids with distinct headgroups were measured and found to be significantly lower than calculated values. It was also found that lipid-lipid interaction has a strong impact on the pK(a) values of lipids. Lysis of model biomembranes by cationic lipids was used to evaluate the impact of lipid pK(a) on the interaction between cationic lipids and cell membranes. It was found that cationic lipid-biomembrane interaction depends strongly on lipid pK(a) and solution pH, and this interaction is much stronger when amino lipids are highly charged. The presence of an optimal pK(a) range of ionizable amino lipids for siRNA delivery was suggested based on these results. The pK(a) methods reported here can be used to support the SAR screen of cationic lipids for siRNA delivery, and the information revealed through studying the impact of pK(a) on the interaction between cationic lipids and cell membranes will contribute significantly to the design of more efficient siRNA delivery vehicles.

  20. Lipid bilayers and interfaces

    NARCIS (Netherlands)

    Kik, R.A.

    2007-01-01

    In biological systems lipid bilayers are subject to many different interactions with other entities. These can range from proteins that are attached to the hydrophilic region of the bilayer or transmembrane proteins that interact with the hydrophobic region of the lipid bilayer. Interaction between

  1. The lipid raft proteome of Borrelia burgdorferi.

    Science.gov (United States)

    Toledo, Alvaro; Pérez, Alberto; Coleman, James L; Benach, Jorge L

    2015-11-01

    Eukaryotic lipid rafts are membrane microdomains that have significant amounts of cholesterol and a selective set of proteins that have been associated with multiple biological functions. The Lyme disease agent, Borrelia burgdorferi, is one of an increasing number of bacterial pathogens that incorporates cholesterol onto its membrane, and form cholesterol glycolipid domains that possess all the hallmarks of eukaryotic lipid rafts. In this study, we isolated lipid rafts from cultured B. burgdorferi as a detergent resistant membrane (DRM) fraction on density gradients, and characterized those molecules that partitioned exclusively or are highly enriched in these domains. Cholesterol glycolipids, the previously known raft-associated lipoproteins OspA and OpsB, and cholera toxin partitioned into the lipid rafts fraction indicating compatibility with components of the DRM. The proteome of lipid rafts was analyzed by a combination of LC-MS/MS or MudPIT. Identified proteins were analyzed in silico for parameters that included localization, isoelectric point, molecular mass and biological function. The proteome provided a consistent pattern of lipoproteins, proteases and their substrates, sensing molecules and prokaryotic homologs of eukaryotic lipid rafts. This study provides the first analysis of a prokaryotic lipid raft and has relevance for the biology of Borrelia, other pathogenic bacteria, as well as for the evolution of these structures. All MS data have been deposited in the ProteomeXchange with identifier PXD002365 (http://proteomecentral.proteomexchange.org/dataset/PXD002365).

  2. Big, Fat World of Lipids

    Science.gov (United States)

    ... Science Home Page The Big, Fat World of Lipids By Emily Carlson Posted August 9, 2012 Cholesterol ... ways to diagnose and treat lipid-related conditions. Lipid Encyclopedia Just as genomics and proteomics spurred advances ...

  3. Single-component solid lipid nanocarriers prepared with ultra-long chain amphiphilic lipids

    DEFF Research Database (Denmark)

    Wei, Wei; Lu, Xiaonan; Wang, Zegao

    2017-01-01

    HYPOTHESIS: Synthetic sugar alcohol mono-behenates with high melting points, surface activity and resistance to enzymatic lipolysis, are expected to form stable single-component solid lipid nanocarriers (SC-SLNs). The preparation methods and the polar head group of the molecules should affect...... the smallest mean size (∼100nm with PdI of 0.26). In addition, they displayed high entrapment efficiency of fenofibrate (95%) and long term drug release. Nanocarriers prepared by emulsification-diffusion method entrapped fenofibrate into lipid bilayers. In contrast, Nanocarriers prepared by melting......-probe sonication method had a micelle structure with fenofibrate incorporated into a lipid monolayer. This study provides an insight into the systematic development of novel amphiphilic lipids for solid lipid-based drug delivery system....

  4. Avanti lipid tools: connecting lipids, technology, and cell biology.

    Science.gov (United States)

    Sims, Kacee H; Tytler, Ewan M; Tipton, John; Hill, Kasey L; Burgess, Stephen W; Shaw, Walter A

    2014-08-01

    Lipid research is challenging owing to the complexity and diversity of the lipidome. Here we review a set of experimental tools developed for the seasoned lipid researcher, as well as, those who are new to the field of lipid research. Novel tools for probing protein-lipid interactions, applications for lipid binding antibodies, enhanced systems for the cellular delivery of lipids, improved visualization of lipid membranes using gold-labeled lipids, and advances in mass spectrometric analysis techniques will be discussed. Because lipid mediators are known to participate in a host of signal transduction and trafficking pathways within the cell, a comprehensive lipid toolbox that aids the science of lipidomics research is essential to better understand the molecular mechanisms of interactions between cellular components. This article is part of a Special Issue entitled Tools to study lipid functions.

  5. Carbon-13 nuclear magnetic resonance spectroscopy of lipids: Differential line broadening due to cross-correlation effects as a probe of membrane structure

    Energy Technology Data Exchange (ETDEWEB)

    Oldfield, E.; Adebodun, F.; Chung, J.; Montez, B.; Ki Deok Park; Hongbiao Le; Phillips, B. (Univ. of Illinois, Urbana (United States))

    1991-11-19

    The authors have obtained proton-coupled carbon-13 nuclear magnetic resonance (NMR) spectra of a variety of lipid-water and lipid-drug-water systems, at 11.7 T, as a function of temperature, using the 'magic-angle' sample-spinning (MAS) NMR technique. The resulting spectra show a wide range of line shapes, due to interferences between dipole-dipole and dipole-chemical shielding anisotropy interactions. The differential line-broadening effects observed are particularly large for aromatic and olefinic (sp{sup 2}) carbon atom sites. Coupled spectra of the tricyclic antidepressants desipramine and imipramine, in 1,2-dimyristoyl-sn-glycero-3-phosphocholine-water mesophases, show well-resolved doublets having different line shapes for each of the four aromatic methine groups, due to selective averaging of the four C-H dipolar interactions due to rapid motion about the director (or drug C{sub 2}) axis. {sup 2}H NMR spectra of (2,4,6,8-{sup 2}H{sub 4})desipramine (and imipramine) in the same 1,2-dimyristoyl-sn-glycero-3-phosphocholine-water mesophase exhibit quadrupole splittings of {approximately}0-2 and {approximately}20 kHz, indicating an approximate magic-angle orientation of the C2-{sup 2}H({sup 1}H) and C8-{sup 2}H({sup 1}H) vectors with respect to an axis of motional averaging, in accord with the {sup 13}C NMR results. The good qualitative agreement between {sup 13}C and {sup 2}H NMR results suggests that useful orientational ({sup 2}H NMR like) information can be deduced from natural-abundance {sup 13}C NMR spectra of a variety of mobile solids.

  6. Insights into thermophilic archaebacterial membrane stability from simplified models of lipid membranes

    Science.gov (United States)

    Davis, Charles H.; Nie, Huifen; Dokholyan, Nikolay V.

    2007-05-01

    Lipid aggregation into fluid bilayers is an essential process for sustaining life. Simplified models of lipid structure, which allow for long time scales or large length scales not obtainable with all-atom simulations, have recently been developed and show promise for describing lipid dynamics in biological systems. Here, we describe two simplified models, a reduced-lipid model and a bola-lipid model for thermophilic bacterial membranes, developed for use with the rapid discrete molecular dynamics simulation method. In the reduced-lipid model, we represent the lipid chain by a series of three beads interacting through pairwise discrete potentials that model hydrophobic attractions between hydrocarbon tails in implicit solvent. Our phase diagram recapitulates those produced by continuous potential models with similar coarse-grained lipid representations. We also find that phase transition temperatures for our reduced-lipid model are dependent upon the flexibility of the lipid chain, giving an insight into archaebacterial membrane stability and prompting development of a bola-lipid model specific for archaebacteria lipids. With both the reduced-lipid and bola-lipid model, we find that the reduced flexibility inherent in archaebacteria lipids yields more stable bilayers as manifested by increased phase transition temperatures. The results of these studies provide a simulation methodology for lipid molecules in biological systems and show that discrete molecular dynamics is applicable to lipid aggregation and dynamics.

  7. Computational studies of plasma lipoprotein lipids.

    Science.gov (United States)

    Pan, Lurong; Segrest, Jere P

    2016-10-01

    Plasma lipoproteins are macromolecular assemblies of proteins and lipids found in the blood. The lipid components of lipoproteins are amphipathic lipids such as phospholipids (PLs), and unesterified cholesterols (UCs) and hydrophobic lipids such as cholesteryl esters (CEs) and triglycerides (TGs). Since lipoproteins are soft matter supramolecular assemblies easily deformable by thermal fluctuations and they also exist in varying densities and protein/lipid components, a detailed understanding of their structure/function is experimentally difficult. Molecular dynamics (MD) simulation has emerged as a particularly promising way to explore the structure and dynamics of lipoproteins. The purpose of this review is to survey the current status of computational studies of the lipid components of the lipoproteins. Computational studies aim to explore three levels of complexity for the 3-dimensional structural dynamics of lipoproteins at various metabolic stages: (i) lipoprotein particles consist of protein with minimal lipid; (ii) lipoprotein particles consist of PL-rich discoidal bilayer-like lipid particles; (iii) mature circulating lipoprotein particles consist of CE-rich or TG-rich spheroidal lipid-droplet-like particles. Due to energy barriers involved in conversion between these species, other biomolecules also participate in lipoprotein biological assembly. For example: (i) lipid-poor apolipoprotein A-I (apoA-I) interacts with ATP-binding cassette transporter A1 (ABCA1) to produce nascent discoidal high density lipoprotein (dHDL) particles; (ii) lecithin-cholesterol acyltransferase (LCAT) mediates the conversion of UC to CE in dHDL, driving spheroidal HDL (sHDL) formation; (iii) transfer proteins, cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP), transfer both CE and TG and PL, respectively, between lipoprotein particles. Computational studies have the potential to explore different lipoprotein particles at each metabolic stage in

  8. Ether lipids from thermophilic archaea; Konetsusei kosaikin no eteru shishitsu

    Energy Technology Data Exchange (ETDEWEB)

    Sugai, A. [Kitazato Univ., Kanagawa (Japan). Center of Liberal Arts and Sciences

    1997-05-20

    The lipids of the archaebacteria grown at ambient temperature are fundamentally archaeol in which sn-2 and sn-3 of glycerol are ether linked with C20 phytanol, while the lipids of the archaebacteria grown at high temperature are mainly caldarchaeol of a tetraether type with a structure in which two molecules of confronted diether lipid are linked by condensation of each hydrocarbon terminal or calditocaldarchaeol incorporating calditol instead of one of two glycerol moieties. The thermophilic archaea is classified into two types, i.e., those grown in a strongly acidic condition and others living around neutral condition. The former consists of tetraether type lipids without exception. Main lipids of the archaea belonging to family Sulfolobaceae are calditocaldarchaeol. This characteristic structure probably contribute to the acid resistance and thermal resistance of these archaea. The present status of the studies on the lipids from thermophilic archaea grown around neutral condition under high pressure are also outlined. 39 refs., 4 figs., 2 tabs.

  9. Lake Superior lipids

    Science.gov (United States)

    Fish chemistry data (d13C, d15N, C:N, lipid content) published in Rapid Commun. Mass Spectrom. 2015, 29, 2069??2077 DOI: 10.1002/rcm.7367This dataset is associated with the following publication:Hoffman , J., M. Sierszen , and A. Cotter. Fish tissue lipid-C:N relationships for correcting ä13C values and estimating lipid content in aquatic food web studies. Rapid Communications in Mass Spectrometry. Wiley InterScience, Silver Spring, MD, USA, 29(21): 2069–2077, (2015).

  10. Lipid raft: A floating island of death or survival

    Energy Technology Data Exchange (ETDEWEB)

    George, Kimberly S. [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States); Department of Chemistry, Marietta College, Marietta, OH 45750 (United States); Wu, Shiyong, E-mail: wus1@ohio.edu [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States)

    2012-03-15

    Lipid rafts are microdomains of the plasma membrane enriched in cholesterol and sphingolipids, and play an important role in the initiation of many pharmacological agent-induced signaling pathways and toxicological effects. The structure of lipid rafts is dynamic, resulting in an ever-changing content of both lipids and proteins. Cholesterol, as a major component of lipid rafts, is critical for the formation and configuration of lipid raft microdomains, which provide signaling platforms capable of activating both pro-apoptotic and anti-apoptotic signaling pathways. A change of cholesterol level can result in lipid raft disruption and activate or deactivate raft-associated proteins, such as death receptor proteins, protein kinases, and calcium channels. Several anti-cancer drugs are able to suppress growth and induce apoptosis of tumor cells through alteration of lipid raft contents via disrupting lipid raft integrity. -- Highlights: ► The role of lipid rafts in apoptosis ► The pro- and anti-apoptotic effects of lipid raft disruption ► Cancer treatments targeting lipid rafts.

  11. Interfacial & colloidal aspects of lipid digestion.

    Science.gov (United States)

    Wilde, P J; Chu, B S

    2011-06-09

    Amongst the main issues challenging the food manufacturing sector, health and nutrition are becoming increasingly important. Global concerns such as obesity, the ageing population and food security will have to be addressed. Food security is not just about assuring food supply, but is also about optimising nutritional delivery from the food that is available [1]. Therefore one challenge is to optimise the health benefits from the lipids and lipid soluble nutrients. Colloid scientists have an affinity for lipids because they are water insoluble, however this presents a challenge to the digestive system, which has to convert them to structures that are less insoluble so they are available for uptake. Despite this, the human digestive system is remarkably effective at digesting and absorbing most lipids. This is primarily driven through maximising energy intake, as lipids possess the highest calorific value, which was a survival trait to survive times of famine, but is now an underlying cause of obesity in developed countries with high food availability. The critical region here is the lipid-water interface, where the key reactions take place to solubilise lipids and lipid soluble nutrients. Digestive lipases have to adsorb to the oil water interface in order to hydrolyse triacylglycerols into fatty acids and mono glycerides, which accumulate at the interface [2], and inhibit lipase activity. Pancreatic lipase, which is responsible for the majority of lipid hydrolysis, also requires the action of bile salts and colipase to function effectively. Bile salts both aid the adsorption of co-lipase and lipase, and help solubilise the lipolysis products which have accumulated at the interface, into mixed micelles composing bile salts and a range of other lipids, to facilitate transport to the gut mucosal surface prior to uptake and absorption. The process can be affected by the lipid type, as shorter chain, fatty acids are more easily absorbed, whereas the uptake of longer

  12. Radioinduced lipid peroxidation: factors determining the oxidizability of lipids; De la peroxydation lipidique radioinduite: les facteurs determinant l'oxydabilite des lipides

    Energy Technology Data Exchange (ETDEWEB)

    Remita, S. [Lab. de Chimie et Biochimie Pharmacologiques et Toxicologiques, Groupe de Chimie-Physique, Unite Mixte de Recherche, Centre National de la Recherche Scientifique, Univ. Paris (France)

    2001-02-01

    Lipids are the essential components of cell membranes and lipoproteins. Their peroxidation plays an important role in numerous pathologies in which oxidative stress is involved. Lipid peroxidation occurs through a chain reaction that contributes to membrane damage in cells. It results in the conversion of fatty acids to polar hydroperoxides and leads to the breakdown or malfunction of the membrane. Lipids are amphiphilic molecules that aggregate in aqueous solutions into micelles and liposoms. The effect of this structural organization is significant in studies of radiation-induced peroxidation damage in highly ordered biological systems such as biological membranes. In this paper, a synthesis of the data concerning radioinduced lipid peroxidation is completed by an original review of the different parameters that determine lipid oxidizability. In addition, the influence of lipid aggregation and the effect of molecular packing are discussed. (author)

  13. Brominated lipids identify lipid binding sites on the surface of the reaction center from Rhodobacter sphaeroides.

    Science.gov (United States)

    Roszak, Aleksander W; Gardiner, Alastair T; Isaacs, Neil W; Cogdell, Richard J

    2007-03-20

    This study describes the use of brominated phospholipids to distinguish between lipid and detergent binding sites on the surface of a typical alpha-helical membrane protein. Reaction centers isolated from Rhodobacter sphaeroides were cocrystallized with added brominated phospholipids. X-ray structural analysis of these crystals has revealed the presence of two lipid binding sites from the characteristic strong X-ray scattering from the bromine atoms. These results demonstrate the usefulness of this approach to mapping lipid binding sites at the surface of membrane proteins.

  14. 443 Review Lipids

    African Journals Online (AJOL)

    Marinda

    2009-07-20

    Jul 20, 2009 ... Keywords: lipid emulsion therapy; local anaesthetic toxicity; local anaesthetic cardiotoxicity; .... of particular importance in generating sufficient ATP from fats because ..... Propofol is poorly water soluble and is dissolved in the.

  15. Metabolism. Part III: Lipids.

    Science.gov (United States)

    Bodner, George M.

    1986-01-01

    Describes the metabolic processes of complex lipids, including saponification, activation and transport, and the beta-oxidation spiral. Discusses fatty acid degradation in regard to biochemical energy and ketone bodies. (TW)

  16. Lipid-modifying therapy

    African Journals Online (AJOL)

    2009-03-20

    Mar 20, 2009 ... risk reduction for most patients, while patients with severe ... He runs the Diabetic, Endocrine and Lipid clinics at R K Khan Hospital. Treatment .... retinopathy requiring laser therapy). ... Despite knowledge of the risk factors for.

  17. Dynamic Transbilayer Lipid Asymmetry

    OpenAIRE

    van Meer, Gerrit

    2011-01-01

    Flippases move lipids from the outer leaflet of the membrane to the inner leaflet; floppases export them in the opposite direction. This creates an asymmetry critical for membrane function and facilitates vesicle budding.

  18. The Ins and Outs of Lipid Flip-Flop.

    Science.gov (United States)

    Allhusen, John S; Conboy, John C

    2017-01-17

    process. By means of transition state theory, the contributions from enthalpy and entropy on the activation energy barrier to lipid flip-flop have been explored in detail for a variety of lipid species and membrane compositions. Specifically, the effect of lipid structure and packing and the inclusion of cholesterol and transmembrane peptides on the rates and thermodynamics of lipid translocation have been investigated in detail. It is our hope that these studies will provide a new perspective on lipid translocation in biological membranes and the role of lipid flip-flop in generating and maintaining cell membrane lipid asymmetry.

  19. Cristalização de lipídios estruturados obtidos a partir de gordura do leite e óleo de milho Crystallization of structured lipids from milkfat and corn oil

    Directory of Open Access Journals (Sweden)

    Juliana Neves Rodrigues

    2003-03-01

    Full Text Available A partir da mistura de óleos e gorduras e de posterior interesterificação podem ser obtidos lipídios estruturados, que são compostos que apresentam características físicas, químicas e nutricionais diferentes daquelas dos lipídios que lhes deram origem. As principais propriedades físicas destes lipídios, como consistência e plasticidade, podem ser influenciadas por sua estrutura cristalina. O objetivo deste trabalho foi observar modificações na estrutura cristalina de lipídios estruturados obtidos a partir de gordura do leite e óleo de milho. As curvas de cinética de cristalização foram construídas a partir do conteúdo de gordura sólida das amostras em função do tempo. A utilização do cálculo dos parâmetros de Avrami permitiu determinar a velocidade de cristalização e os tipos de nucleação e dos cristais formados. A microscopia sob luz polarizada forneceu imagens dos cristais formados pelos métodos de resfriamento lento e rápido, a partir das quais foram determinados os seguintes itens: número de cristais, área cristalizada e dimensões fractais das amostras. A correlação obtida entre os resultados indicou que a adição de óleo de milho não provocou mudanças substanciais na estrutura da rede cristalina da gordura do leite, apenas diminuiu a quantidade de gordura cristalizada. As reações de interesterificação e a adição de óleo de milho não alteraram o tamanho e a forma dos cristais.Structured lipids can be obtained by blending and chemical interesterification of fats and oils, resulting in products with physical, chemical and nutritional characteristics that are different from the original lipids. The most important physical properties of these lipids, such as consistency and plasticity, may be influenced by their crystalline structure. The objective of this study was to observe the changes in the crystal network of structured lipids obtained from milkfat and corn oil. The kinetic crystallization

  20. Antithrombotic lipids from Semen Persicae.

    Science.gov (United States)

    Yang, Nian-Yun; Liu, Li; Tao, Wei-Wei; Duan, Jin-Ao; Liu, Xun-Hong; Huang, Su-Ping

    2011-10-01

    Chemical investigation of Semen Persicae has led to the isolation of decane (1), triolein (2), nonacosanoic acid (3), oleic acid ethyl ester (4), palmitic acid (5), oleic acid (6) and 15,16-dihydroxy-9Z,12Z-octadecadienoic acid 2,3-dihydroxypropyl ester (7). Amongst these, compound 7 is a new lipid. Their structures were elucidated by chemical and extensive spectral analysis. Their anticoagulative activities were also evaluated in vitro, which showed that petroleum ether extract and compounds 5-6 could significantly prolong thrombin time while methanol extract could obviously inhibit platelet aggregation.

  1. Lipids of mitochondria.

    Science.gov (United States)

    Horvath, Susanne E; Daum, Günther

    2013-10-01

    A unique organelle for studying membrane biochemistry is the mitochondrion whose functionality depends on a coordinated supply of proteins and lipids. Mitochondria are capable of synthesizing several lipids autonomously such as phosphatidylglycerol, cardiolipin and in part phosphatidylethanolamine, phosphatidic acid and CDP-diacylglycerol. Other mitochondrial membrane lipids such as phosphatidylcholine, phosphatidylserine, phosphatidylinositol, sterols and sphingolipids have to be imported. The mitochondrial lipid composition, the biosynthesis and the import of mitochondrial lipids as well as the regulation of these processes will be main issues of this review article. Furthermore, interactions of lipids and mitochondrial proteins which are highly important for various mitochondrial processes will be discussed. Malfunction or loss of enzymes involved in mitochondrial phospholipid biosynthesis lead to dysfunction of cell respiration, affect the assembly and stability of the mitochondrial protein import machinery and cause abnormal mitochondrial morphology or even lethality. Molecular aspects of these processes as well as diseases related to defects in the formation of mitochondrial membranes will be described. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Oxygen as a paramagnetic probe for nuclear magnetic resonance: structure and paramagnetic profile of a lipid bilayer/membrane model system

    Energy Technology Data Exchange (ETDEWEB)

    Al-Abdul Wahid, M.S

    2005-07-01

    Paramagnetic contact shifts and relaxation rate enhancements from molecular oxygen dissolved in a model membrane, were studied by nuclear magnetic resonance spectroscopy. The model membrane system was an isotropic bicelle formed using 1-myristelaidoyl-2-myristoyl-d27-sn- glycero-3-phosphocholine (MLMPC), a custom phospholipid, and 1-2-dihexanoyl-d22-sn-glycero-3-phosphocholine (DHPC). The {sup 13}C and {sup 1}H spectra of MLMPC were assigned. Molecular oxygen was delivered at external pressures of 20 and 50 atm. Paramagnetic contact shifts were found to scale with the oxygen solubility gradient in the lipid bilayer, were found to be invariant to temperature changes in the region studied (288K to 331K), and scaled linearly with changes in oxygen pressure. Relaxation rate enhancements from oxygen were low in the headgroup region and increased to a roughly constant rate in the acyl chain region. Rates were comparable to values predicted by simple thermodynamic theories which take into account the observed gradients in diffusion rates and solubility of oxygen in bilayers. (author)

  3. The C-terminal region of the non-structural protein 2B from Hepatitis A Virus demonstrates lipid-specific viroporin-like activity

    Science.gov (United States)

    Shukla, Ashutosh; Dey, Debajit; Banerjee, Kamalika; Nain, Anshu; Banerjee, Manidipa

    2015-10-01

    Viroporins are virally encoded, membrane-active proteins, which enhance viral replication and assist in egress of viruses from host cells. The 2B proteins in the picornaviridae family are known to have viroporin-like properties, and play critical roles during virus replication. The 2B protein of Hepatitis A Virus (2B), an unusual picornavirus, is somewhat dissimilar from its analogues in several respects. HAV 2B is approximately 2.5 times the length of other 2B proteins, and does not disrupt calcium homeostasis or glycoprotein trafficking. Additionally, its membrane penetrating properties are not yet clearly established. Here we show that the membrane interacting activity of HAV 2B is localized in its C-terminal region, which contains an alpha-helical hairpin motif. We show that this region is capable of forming small pores in membranes and demonstrates lipid specific activity, which partially rationalizes the intracellular localization of full-length 2B. Using a combination of biochemical assays and molecular dynamics simulation studies, we also show that HAV 2B demonstrates a marked propensity to dimerize in a crowded environment, and probably interacts with membranes in a multimeric form, a hallmark of other picornavirus viroporins. In sum, our study clearly establishes HAV 2B as a bona fide viroporin in the picornaviridae family.

  4. Mechanical Properties of Nanoscopic Lipid Domains.

    Science.gov (United States)

    Nickels, Jonathan D; Cheng, Xiaolin; Mostofian, Barmak; Stanley, Christopher; Lindner, Benjamin; Heberle, Frederick A; Perticaroli, Stefania; Feygenson, Mikhail; Egami, Takeshi; Standaert, Robert F; Smith, Jeremy C; Myles, Dean A A; Ohl, Michael; Katsaras, John

    2015-12-23

    The lipid raft hypothesis presents insights into how the cell membrane organizes proteins and lipids to accomplish its many vital functions. Yet basic questions remain about the physical mechanisms that lead to the formation, stability, and size of lipid rafts. As a result, much interest has been generated in the study of systems that contain similar lateral heterogeneities, or domains. In the current work we present an experimental approach that is capable of isolating the bending moduli of lipid domains. This is accomplished using neutron scattering and its unique sensitivity to the isotopes of hydrogen. Combining contrast matching approaches with inelastic neutron scattering, we isolate the bending modulus of ∼13 nm diameter domains residing in 60 nm unilamellar vesicles, whose lipid composition mimics the mammalian plasma membrane outer leaflet. Importantly, the bending modulus of the nanoscopic domains differs from the modulus of the continuous phase surrounding them. From additional structural measurements and all-atom simulations, we also determine that nanoscopic domains are in-register across the bilayer leaflets. Taken together, these results inform a number of theoretical models of domain/raft formation and highlight the fact that mismatches in bending modulus must be accounted for when explaining the emergence of lateral heterogeneities in lipid systems and biological membranes.

  5. Omental Lipid-Coated Mesh

    Science.gov (United States)

    2011-06-16

    civilian medicine. REFERENCES: 1. Takada T, Kamei Y, Iwata T, et al. Effect of Omental Lipid Fraction on Enhancement of Skin Flap Survival. Annals of...Characterization of Feline Omentum Lipids. Lipids, 1987; 22:229-235. 7. Nottebaert M, Lane J, Juhn A, et al. Omental Angiogenic Lipid Fraction and

  6. Proteomic profiling of lipid droplet-associated proteins in primary adipocytes of normal and obese mouse

    Institute of Scientific and Technical Information of China (English)

    Yubo Ding; Yibo Wu; Rong Zeng; Kan Liao

    2012-01-01

    Lipid droplets in adipocytes serve as the principal longterm energy storage depot of animals.There is increasing recognition that lipid droplets are not merely a static neutral lipid storage site,but in fact dynamic and multifunctional organelles.Structurally,lipid droplet consists of a neutral lipid core surrounded by a phospholipid monolayer and proteins embedded in or bound to the phospholipid layer.Proteins on the surface of lipid droplets are crucial to droplet structure and dynamics.To understand the lipid droplet-associated proteome of primary adipocyte with a large central lipid droplet,lipid droplets of white adipose tissue from C57BL/6 mice were isolated.And the proteins were extracted and analyzed by liquid chromatography coupled with tandem mass spectrometry.A total of 193 proteins including 73 previously unreported proteins were identified.Furthermore,the isotope-coded affinity tags (ICAT) was used to compare the difference of lipid droplet-associated proteomes between the normal lean and the high-fat diet-induced obese C57BL/6 mice.Of 23proteins quantified by ICAT analysis,3 proteins were upregulated and 4 proteins were down-regulated in the lipid droplets of adipose tissue from the obese mice.Importantly,two structural proteins of lipid droplets,perilipin A and vimentin,were greatly reduced in the lipid droplets of the adipose tissue from the obese mice,implicating reduced protein machinery for lipid droplet stability.

  7. Do Lipids Retard the Evaporation of the Tear Fluid?

    DEFF Research Database (Denmark)

    Rantamaki, A. H.; Javanainen, M.; Vattulainen, I.

    2012-01-01

    . Lipids were applied to an air-water interface, and the evaporation rate through the lipid layer was defined as water loss from the interface. A thick layer of olive oil and a monolayer of long-chain alcohol were used as controls. The artificial TFLLs were composed of 1 to 4 lipid species: polar...... phosphatidylcholine (PC), nonpolar cholesteryl ester, triglycerides, and wax ester (WE). Brewster angle microscopy (BAM) and interfacial shear rheometry (ISR) were used to assess the lateral structure and shear stress response of the lipid layers, respectively. RESULTS. Olive oil and long-chain alcohol decreased...

  8. Parenteral lipids impair pneumococcal elimination by human neutrophils.

    NARCIS (Netherlands)

    Versleijen, M.W.J.; Roelofs, H.M.J.; Morsche, R.H.M. te; Simonetti, E.R.; Hermans, P.W.M.; Wanten, G.J.A.

    2010-01-01

    BACKGROUND: Lipid-induced modulation of phagocyte function seems to contribute to increased susceptibility to infections in patients on parenteral nutrition, and an increased risk for development of pneumonia has been observed in this group. The role of various structurally different lipid emulsions

  9. How protein transmembrane segments sense the lipid environment

    NARCIS (Netherlands)

    Nyholm, T.K.M.; Özdirekcan, S.; Killian, J.A.

    2007-01-01

    Integral membrane proteins have central roles in a vast number of vital cellular processes. A structural feature that most membrane proteins have in common is the presence of one or more R-helices with which they traverse the lipid bilayer. Because of the interaction with the surrounding lipids, the

  10. Pushing the lipid envelope: using bio-inspired nanocomposites to understand and exploit lipid membrane limitations

    Science.gov (United States)

    Montano, Gabriel

    Lipids serve as the organizing matrix material for biological membranes, the site of interaction of cells with the external environment. . As such, lipids play a critical role in structure/function relationships of an extraordinary number of critical biological processes. In this talk, we will look at bio-inspired membrane assemblies to better understand the roles of lipids in biological systems as well as attempt to generate materials that can mimic and potentially advance upon biological membrane processes. First, we will investigate the response of lipids to adverse conditions. In particular, I will present data that demonstrates the response of lipids to harsh conditions and how such responses can be exploited to generate nanocomposite rearrangements. I will also show the effect of adding the endotoxin lipopolysaccharide (LPS) to lipid bilayer assemblies and describe implications on our understanding of LPS organization in biological systems as well as describe induced lipid modifications that can be exploited to organize membrane composites with precise, two-dimensional geometric control. Lastly, I will describe the use of amphiphilic block copolymers to create membrane nanocomposites capable of mimicking biological systems. In particular, I will describe the use of our polymer-based membranes in creating artificial photosynthetic assemblies that rival biological systems in function in a more flexible, dynamic matrix.

  11. Function and regulation of lipid biology in Caenorhabditis elegans aging

    Directory of Open Access Journals (Sweden)

    Nicole Shangming Hou

    2012-05-01

    Full Text Available Rapidly expanding aging populations and a concomitant increase in the prevalence of age-related diseases are global health problems today. Over the past three decades, a large body of work has led to the identification of genes and regulatory networks that affect longevity and health span, often benefitting from the tremendous power of genetics in vertebrate and invertebrate model organisms. Interestingly, many of these factors appear linked to lipids, important molecules that participate in cellular signaling, energy metabolism, and structural compartmentalization. Despite the putative link between lipids and longevity, the role of lipids in aging remains poorly understood. Emerging data from the model organism Caenorhabditis elegans suggest that lipid composition may change during aging, as several pathways that influence aging also regulate lipid metabolism enzymes; moreover, some of these enzymes apparently play key roles in the pathways that affect the rate of aging. By understanding how lipid biology is regulated during C. elegans aging, and how it impacts molecular, cellular and organismal function, we may gain insight into novel ways to delay aging using genetic or pharmacological interventions. In the present review we discuss recent insights into the roles of lipids in C. elegans aging, including regulatory roles played by lipids themselves, the regulation of lipid metabolic enzymes, and the roles of lipid metabolism genes in the pathways that affect aging.

  12. Function and Regulation of Lipid Biology in Caenorhabditis elegans Aging

    Science.gov (United States)

    Hou, Nicole Shangming; Taubert, Stefan

    2012-01-01

    Rapidly expanding aging populations and a concomitant increase in the prevalence of age-related diseases are global health problems today. Over the past three decades, a large body of work has led to the identification of genes and regulatory networks that affect longevity and health span, often benefiting from the tremendous power of genetics in vertebrate and invertebrate model organisms. Interestingly, many of these factors appear linked to lipids, important molecules that participate in cellular signaling, energy metabolism, and structural compartmentalization. Despite the putative link between lipids and longevity, the role of lipids in aging remains poorly understood. Emerging data from the model organism Caenorhabditis elegans suggest that lipid composition may change during aging, as several pathways that influence aging also regulate lipid metabolism enzymes; moreover, some of these enzymes apparently play key roles in the pathways that affect the rate of aging. By understanding how lipid biology is regulated during C. elegans aging, and how it impacts molecular, cellular, and organismal function, we may gain insight into novel ways to delay aging using genetic or pharmacological interventions. In the present review we discuss recent insights into the roles of lipids in C. elegans aging, including regulatory roles played by lipids themselves, the regulation of lipid metabolic enzymes, and the roles of lipid metabolism genes in the pathways that affect aging. PMID:22629250

  13. Langmuir monolayers composed of single and double tail sulfobetaine lipids.

    Science.gov (United States)

    Hazell, Gavin; Gee, Anthony P; Arnold, Thomas; Edler, Karen J; Lewis, Simon E

    2016-07-15

    Owing to structural similarities between sulfobetaine lipids and phospholipids it should be possible to form stable Langmuir monolayers from long tail sulfobetaines. By modification of the density of lipid tail group (number of carbon chains) it should also be possible to modulate the two-dimensional phase behaviour of these lipids and thereby compare with that of equivalent phospholipids. Potentially this could enable the use of such lipids for the wide array of applications that currently use phospholipids. The benefit of using sulfobetaine lipids is that they can be synthesised by a one-step reaction from cheap and readily available starting materials and will degrade via different pathways than natural lipids. The molecular architecture of the lipid can be easily modified allowing the design of lipids for specific purposes. In addition the reversal of the charge within the sulfobetaine head group relative to the charge orientation in phospholipids may modify behaviour and thereby allow for novel uses of these surfactants. Stable Langmuir monolayers were formed composed of single and double tailed sulfobetaine lipids. Surface pressure-area isotherm, Brewster Angle Microscopy and X-ray and neutron reflectometry measurements were conducted to measure the two-dimensional phase behaviour and out-of-plane structure of the monolayers as a function of molecular area. Sulfobetaine lipids are able to form stable Langmuir monolayers with two dimensional phase behaviour analogous to that seen for the well-studied phospholipids. Changing the number of carbon tail groups on the lipid from one to two promotes the existence of a liquid condensed phase due to increased Van der Waals interactions between the tail groups. Thus the structure of the monolayers appears to be defined by the relative sizes of the head and tail groups in a predictable way. However, the presence of sub-phase ions has little effect on the monolayer structure, behaviour that is surprisingly different to

  14. Microalgal lipid droplets: composition, diversity, biogenesis and functions.

    Science.gov (United States)

    Goold, Hugh; Beisson, Fred; Peltier, Gilles; Li-Beisson, Yonghua

    2015-04-01

    Lipid droplet is the major site of neutral lipid storage in eukaryotic cells, and increasing evidence show its involvement in numerous cellular processes such as lipid homeostasis, signaling, trafficking and inter-organelle communications. Although the biogenesis, structure, and functions of lipid droplets have been well documented for seeds of vascular plants, mammalian adipose tissues, insects and yeasts, relative little is known about lipid droplets in microalgae. Over the past 5 years, the growing interest of microalgae as a platform for biofuel, green chemicals or value-added polyunsaturated fatty acid production has brought algal lipid droplets into spotlight. Studies conducted on the green microalga Chlamydomonas reinhardtii and other model microalgae such as Haematococcus and Nannochloropsis species have led to the identification of proteins associated with lipid droplets, which include putative structural proteins different from plant oleosins and animal perilipins, as well as candidate proteins for lipid biosynthesis, mobilization, trafficking and homeostasis. Biochemical and microscopy studies have also started to shed light on the role of chloroplasts in the biogenesis of lipid droplets in Chlamydomonas.

  15. Lipid Vesicles for the Skin Delivery of Diclofenac: Cerosomes vs. Other Lipid Suspensions

    Directory of Open Access Journals (Sweden)

    Anahita Fathi-Azarbayjani

    2015-03-01

    Full Text Available Purpose: Lipid suspensions as drug carriers, including conventional liposomes, ethosomes, transferosomes, proniosomes, niosomes, PEG-PPG-PEG niosomes and stratum corneum liposomes (cerosomes, were formulated and compared. Methods: Lipid vesicles were formulated and assessed with regards to enhancement of skin permeation of diclofenac and stability profiles of the formulations. Formulation-induced changes of the biophysical structure of excised human skin were monitored using the Fourier transform infrared spectroscopy. Results: The stability profiles of these suspensions over 12 weeks did not show any significant drug leakage from the vesicles of interest (p > 0.05. FTIR observations indicated that the vesicles increased stratum corneum (SC lipid fluidization and altered protein conformation. Skin permeability experiments showed that the free unencapsulated drug in the cerosomal formulations caused significant increase in drug permeation across the skin (p < 0.01. Low skin permeability of drug from the other lipid suspensions could be due to the entrapment of diclofenac within these vesicles which decreased the solubility of the hydrophilic drug in the skin lipids and the partition coefficient of the drug from these vesicles into the SC. Conclusion: Optimal drug entrapment in vesicles or alteration of the skin structure may not necessarily enhance the permeation of hydrophilic drugs across the human skin. These lipid vesicles may be further developed into carriers of both hydrophilic and hydrophobic drugs for topical and transdermal delivery, respectively.

  16. Lipid Vesicles for the Skin Delivery of Diclofenac: Cerosomes vs. Other Lipid Suspensions

    Science.gov (United States)

    Fathi-Azarbayjani, Anahita; Ng, Kai Xin; Chan, Yew Weng; Chan, Sui Yung

    2015-01-01

    Purpose: Lipid suspensions as drug carriers, including conventional liposomes, ethosomes, transferosomes, proniosomes, niosomes, PEG-PPG-PEG niosomes and stratum corneum liposomes (cerosomes), were formulated and compared. Methods: Lipid vesicles were formulated and assessed with regards to enhancement of skin permeation of diclofenac and stability profiles of the formulations. Formulation-induced changes of the biophysical structure of excised human skin were monitored using the Fourier transform infrared spectroscopy. Results: The stability profiles of these suspensions over 12 weeks did not show any significant drug leakage from the vesicles of interest (p > 0.05). FTIR observations indicated that the vesicles increased stratum corneum (SC) lipid fluidization and altered protein conformation. Skin permeability experiments showed that the free unencapsulated drug in the cerosomal formulations caused significant increase in drug permeation across the skin (p < 0.01). Low skin permeability of drug from the other lipid suspensions could be due to the entrapment of diclofenac within these vesicles which decreased the solubility of the hydrophilic drug in the skin lipids and the partition coefficient of the drug from these vesicles into the SC. Conclusion: Optimal drug entrapment in vesicles or alteration of the skin structure may not necessarily enhance the permeation of hydrophilic drugs across the human skin. These lipid vesicles may be further developed into carriers of both hydrophilic and hydrophobic drugs for topical and transdermal delivery, respectively. PMID:25789216

  17. NMR Structure of rALF-Pm3, an Anti-Lipopolysaccharide Factor from Shrimp: Model of the Possible Lipid A-Binding Site

    OpenAIRE

    Yang, Yinshan; Boze, Helene; Chemardin, Patrick; Padilla, Andre; Moulin, Guy; Tassanakajon, Anchalee; Pugniere, Martine; Roquet, Francoise; Destoumieux Garzon, Delphine; Gueguen, Yannick; Bachere, Evelyne; Aumelas, Andre

    2009-01-01

    The anti-lipopolysaccharide factor ALF-Pm3 is a 98-residue protein identified in hemocytes from the black tiger shrimp Penaeus monodon. It was expressed in Pichia pastoris from the constitutive glyceraldehyde-3-phosphate dehydrogenase promoter as a folded and N-15 uniformly labeled rALF-Pm3 protein. Its 3D structure was established by NMR and consists of three alpha-helices packed against a four-stranded beta-sheet. The C-34-C-55 disulfide bond was shown to be essential for the structure stab...

  18. Heart, lipids and hormones

    Directory of Open Access Journals (Sweden)

    Peter Wolf

    2017-05-01

    Full Text Available Cardiovascular disease is the leading cause of death in general population. Besides well-known risk factors such as hypertension, impaired glucose tolerance and dyslipidemia, growing evidence suggests that hormonal changes in various endocrine diseases also impact the cardiac morphology and function. Recent studies highlight the importance of ectopic intracellular myocardial and pericardial lipid deposition, since even slight changes of these fat depots are associated with alterations in cardiac performance. In this review, we overview the effects of hormones, including insulin, thyroid hormones, growth hormone and cortisol, on heart function, focusing on their impact on myocardial lipid metabolism, cardiac substrate utilization and ectopic lipid deposition, in order to highlight the important role of even subtle hormonal changes for heart function in various endocrine and metabolic diseases.

  19. LIPID PEROXIDATION IN PREECLAMPSIA

    Directory of Open Access Journals (Sweden)

    T.Sharmila Krishna

    2015-03-01

    Full Text Available Hypertension in pregnancy is a leading cause of both maternal and fetal mortality and morbidity. Preeclampsia is characterised by hypertension and proteinuria. Lipid peroxidation is an important factor in the pathophysiology of Preeclampsia. The present study was undertaken to determine Serum Malondialdehyde (MDA levels , a product of lipid peroxidation , in clinically diagnosed Preeclamptic women(n=30 and the values were compared with that of Normotensive pregnant women (n=30 aged between 18-30yrs. All of them were in their third trimester and were primigravida. Serum MDA was estimated by TBARS (thiobarbituric acid reactive substances method. We observed that Serum MDA levels were significantly increased in Preeclamptic women (p <0.000 as compared to that of Normotensive pregnant women . Increased levels of lipid peroxiation product - MDA may contribute to the pathophysiology of Preeclampsia.

  20. Atomistic study of lipid membranes containing chloroform: looking for a lipid-mediated mechanism of anesthesia.

    Directory of Open Access Journals (Sweden)

    Ramon Reigada

    Full Text Available The molecular mechanism of general anesthesia is still a controversial issue. Direct effect by linking of anesthetics to proteins and indirect action on the lipid membrane properties are the two hypotheses in conflict. Atomistic simulations of different lipid membranes subjected to the effect of small volatile organohalogen compounds are used to explore plausible lipid-mediated mechanisms. Simulations of homogeneous membranes reveal that electrostatic potential and lateral pressure transversal profiles are affected differently by chloroform (anesthetic and carbon tetrachloride (non-anesthetic. Simulations of structured membranes that combine ordered and disordered regions show that chloroform molecules accumulate preferentially in highly disordered lipid domains, suggesting that the combination of both lateral and transversal partitioning of chloroform in the cell membrane could be responsible of its anesthetic action.

  1. Bioorthogonal chemical reporters for analyzing protein lipidation and lipid trafficking.

    Science.gov (United States)

    Hang, Howard C; Wilson, John P; Charron, Guillaume

    2011-09-20

    Protein lipidation and lipid trafficking control many key biological functions in all kingdoms of life. The discovery of diverse lipid species and their covalent attachment to many proteins has revealed a complex and regulated network of membranes and lipidated proteins that are central to fundamental aspects of physiology and human disease. Given the complexity of lipid trafficking and the protein targeting mechanisms involved with membrane lipids, precise and sensitive methods are needed to monitor and identify these hydrophobic molecules in bacteria, yeast, and higher eukaryotes. Although many analytical methods have been developed for characterizing membrane lipids and covalently modified proteins, traditional reagents and approaches have limited sensitivity, do not faithfully report on the lipids of interest, or are not readily accessible. The invention of bioorthogonal ligation reactions, such as the Staudinger ligation and azide-alkyne cycloadditions, has provided new tools to address these limitations, and their use has begun to yield fresh insight into the biology of protein lipidation and lipid trafficking. In this Account, we discuss how these new bioorthogonal ligation reactions and lipid chemical reporters afford new opportunities for exploring the biology of lipid-modified proteins and lipid trafficking. Lipid chemical reporters from our laboratory and several other research groups have enabled improved detection and large-scale proteomic analysis of fatty-acylated and prenylated proteins. For example, fatty acid and isoprenoid chemical reporters in conjunction with bioorthogonal ligation methods have circumvented the limited sensitivity and hazards of radioactive analogues, allowing rapid and robust fluorescent detection of lipidated proteins in all organisms tested. These chemical tools have revealed alterations in protein lipidation in different cellular states and are beginning to provide unique insights in mechanisms of regulation. Notably, the

  2. Data including GROMACS input files for atomistic molecular dynamics simulations of mixed, asymmetric bilayers including molecular topologies, equilibrated structures, and force field for lipids compatible with OPLS-AA parameters

    DEFF Research Database (Denmark)

    Róg, Tomasz; Orłowski, Adam; Llorente, Alicia

    2016-01-01

    In this Data in Brief article we provide a data package of GROMACS input files for atomistic molecular dynamics simulations of multicomponent, asymmetric lipid bilayers using the OPLS-AA force field. These data include 14 model bilayers composed of 8 different lipid molecules. The lipids present ...... (md.mdp). The data is associated with the research article "Interdigitation of Long-Chain Sphingomyelin Induces Coupling of Membrane Leaflets in a Cholesterol Dependent Manner" (Róg et al., 2016) [3]....

  3. Structural analysis of papain-like NlpC/P60 superfamily enzymes with a circularly permuted topology reveals potential lipid binding sites.

    Directory of Open Access Journals (Sweden)

    Qingping Xu

    Full Text Available NlpC/P60 superfamily papain-like enzymes play important roles in all kingdoms of life. Two members of this superfamily, LRAT-like and YaeF/YiiX-like families, were predicted to contain a catalytic domain that is circularly permuted such that the catalytic cysteine is located near the C-terminus, instead of at the N-terminus. These permuted enzymes are widespread in virus, pathogenic bacteria, and eukaryotes. We determined the crystal structure of a member of the YaeF/YiiX-like family from Bacillus cereus in complex with lysine. The structure, which adopts a ligand-induced, "closed" conformation, confirms the circular permutation of catalytic residues. A comparative analysis of other related protein structures within the NlpC/P60 superfamily is presented. Permutated NlpC/P60 enzymes contain a similar conserved core and arrangement of catalytic residues, including a Cys/His-containing triad and an additional conserved tyrosine. More surprisingly, permuted enzymes have a hydrophobic S1 binding pocket that is distinct from previously characterized enzymes in the family, indicative of novel substrate specificity. Further analysis of a structural homolog, YiiX (PDB 2if6 identified a fatty acid in the conserved hydrophobic pocket, thus providing additional insights into possible function of these novel enzymes.

  4. Structural Analysis of Papain-Like NlpC/P60 Superfamily Enzymes with a Circularly Permuted Topology Reveals Potential Lipid Binding Sites

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Qingping; Rawlings, Neil D.; Chiu, Hsiu-Ju; Jaroszewski, Lukasz; Klock, Heath E.; Knuth, Mark W.; Miller, Mitchell D.; Elsliger, Marc-Andre; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A. (SG); (Wellcome)

    2012-07-11

    NlpC/P60 superfamily papain-like enzymes play important roles in all kingdoms of life. Two members of this superfamily, LRAT-like and YaeF/YiiX-like families, were predicted to contain a catalytic domain that is circularly permuted such that the catalytic cysteine is located near the C-terminus, instead of at the N-terminus. These permuted enzymes are widespread in virus, pathogenic bacteria, and eukaryotes. We determined the crystal structure of a member of the YaeF/YiiX-like family from Bacillus cereus in complex with lysine. The structure, which adopts a ligand-induced, 'closed' conformation, confirms the circular permutation of catalytic residues. A comparative analysis of other related protein structures within the NlpC/P60 superfamily is presented. Permutated NlpC/P60 enzymes contain a similar conserved core and arrangement of catalytic residues, including a Cys/His-containing triad and an additional conserved tyrosine. More surprisingly, permuted enzymes have a hydrophobic S1 binding pocket that is distinct from previously characterized enzymes in the family, indicative of novel substrate specificity. Further analysis of a structural homolog, YiiX (PDB 2if6) identified a fatty acid in the conserved hydrophobic pocket, thus providing additional insights into possible function of these novel enzymes.

  5. Structures similar to lipid emulsions and liposomes. Dipalmitoylphosphatidylcholine, cholesterol, Tween 20-Span 20 or Tween 80-Span 80 in aqueous media.

    Science.gov (United States)

    Juárez-Osornio, Carlos; Gracia-Fadrique, Jesús

    2017-06-01

    In the present work, we show that we obtained nanometric structures made of water, 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), cholesterol (Chol), and a mixture of ethoxylated and non-ethoxylated sorbitan fatty acid esters (Tween 20, Span 20, Tween 80, and Span 80) by mixing all of them near the cloud point temperature (cp) of the ethoxylated surfactant. The influence that the constituents had on the size of the particle was determined by a pseudo-ternary phase diagram of water/Tween-Span/DPPC-Chol; the colloidal particles obtained were studied by differential scanning calorimetry, confocal fluorescence microscopy, scanning electron microscopy, and atomic force microscopy. These studies were made for all the systems with at least 23 d of colloidal stability. The most stable system was obtained with the Tween 80-Span 80 pair, behaving as a typical suspension for 48 d; this system was made of water, Tween 80-Span 80 (80:20), DPPC-Chol (95:5) in a corresponding molar ratio of 48:37:100:10. The colloidal particles obtained were a kind of emulsion and liposome structures. The second stable system was obtained with the same mixture, but in a molar ratio of 8:6:9:0, its structure was also a kind of emulsion particles. In both systems and in other less stable ones, the "emulsion particle" was completely new, it structurally corresponds to a nucleus of mixed micelles surrounded by at least one bilayer of DPPC.

  6. Electrostatics of cell membrane recognition: structure and activity of neutral and cationic rigid push-pull rods in isoelectric, anionic, and polarized lipid bilayer membranes.

    Science.gov (United States)

    Sakai, N; Gerard, D; Matile, S

    2001-03-21

    Design, synthesis, and structural and functional studies of rigid-rod ionophores of different axial electrostatic asymmetry are reported. The employed design strategy emphasized presence of (a) a rigid scaffold to minimize the conformational complexity, (b) a unimolecular ion-conducting pathway to minimize the suprastructural complexity and monitor the function, (c) an extended fluorophore to monitor structure, (d) variable axial rod dipole, and (e) variable terminal charges to create axial asymmetry. Studies in isoelectric, anionic, and polarized bilayer membranes confirmed a general increase in activity of uncharged rigid push-pull rods in polarized bilayers. The similarly increased activity of cationic rigid push-pull rods with an electrostatic asymmetry comparable to that of alpha-helical bee toxin melittin (positive charge near negative axial dipole terminus) is shown by fluorescence-depth quenching experiments to originate from the stabilization of transmembrane rod orientation by the membrane potential. The reduced activity of rigid push-pull rods having an electrostatic asymmetry comparable to that in alpha-helical natural antibiotics (a positive charge near the positive axial dipole terminus) is shown by structural studies to originate from rod "ejection" by membrane potentials comparable to that found in mammalian plasma membranes. This structural evidence for cell membrane recognition by asymmetric rods is unprecedented and of possible practical importance with regard to antibiotic resistance.

  7. Oxidizability of unsaturated fatty acids and of a non-phenolic lignin structure in the manganese peroxidase-dependent lipid peroxidation system

    Science.gov (United States)

    Alexander N. Kapich; Tatyana V. Korneichik; Annele Hatakka; Kenneth E. Hammel

    2010-01-01

    Unsaturated fatty acids have been proposed to mediate the oxidation of recalcitrant, non-phenolic lignin structures by fungal manganese peroxidases (MnP), but their precise role remains unknown. We investigated the oxidizability of three fatty acids with varying degrees of polyunsaturation (linoleic, linolenic, and arachidonic acids) by measuring conjugated dienes...

  8. Silica nanoparticles to control the lipase-mediated digestion of lipid-based oral delivery systems.

    Science.gov (United States)

    Tan, Angel; Simovic, Spomenka; Davey, Andrew K; Rades, Thomas; Boyd, Ben J; Prestidge, Clive A

    2010-04-05

    We investigate the role of hydrophilic fumed silica in controlling the digestion kinetics of lipid emulsions, hence further exploring the mechanisms behind the improved oral absorption of poorly soluble drugs promoted by silica-lipid hybrid (SLH) microcapsules. An in vitro lipolysis model was used to quantify the lipase-mediated digestion kinetics of a series of lipid vehicles formulated with caprylic/capric triglycerides: lipid solution, submicrometer lipid emulsions (in the presence and absence of silica), and SLH microcapsules. The importance of emulsification on lipid digestibility is evidenced by the significantly higher initial digestion rate constants for SLH microcapsules and lipid emulsions (>15-fold) in comparison with that of the lipid solution. Silica particles exerted an inhibitory effect on the digestion of submicrometer lipid emulsions regardless of their initial location, i.e., aqueous or lipid phases. This inhibitory effect, however, was not observed for SLH microcapsules. This highlights the importance of the matrix structure and porosity of the hybrid microcapsule system in enhancing lipid digestibility as compared to submicrometer lipid emulsions stabilized by silica. For each studied formulation, the digestion kinetics is well correlated to the corresponding in vivo plasma concentrations of a model drug, celecoxib, via multiple-point correlations (R(2) > 0.97). This supports the use of the lipid digestion model for predicting the in vivo outcome of an orally dosed lipid formulation. SLH microcapsules offer the potential to enhance the oral absorption of poorly soluble drugs via increased lipid digestibility in conjunction with improved drug dissolution/dispersion.

  9. Designing lipids for selective partitioning into liquid ordered membrane domains.

    Science.gov (United States)

    Momin, Noor; Lee, Stacey; Gadok, Avinash K; Busch, David J; Bachand, George D; Hayden, Carl C; Stachowiak, Jeanne C; Sasaki, Darryl Y

    2015-04-28

    Self-organization of lipid molecules into specific membrane phases is key to the development of hierarchical molecular assemblies that mimic cellular structures. While the packing interaction of the lipid tails should provide the major driving force to direct lipid partitioning to ordered or disordered membrane domains, numerous examples show that the headgroup and spacer play important but undefined roles. We report here the development of several new biotinylated lipids that examine the role of spacer chemistry and structure on membrane phase partitioning. The new lipids were prepared with varying lengths of low molecular weight polyethylene glycol (EGn) spacers to examine how spacer hydrophilicity and length influence their partitioning behavior following binding with FITC-labeled streptavidin in liquid ordered (Lo) and liquid disordered (Ld) phase coexisting membranes. Partitioning coefficients (Kp Lo/Ld) of the biotinylated lipids were determined using fluorescence measurements in studies with giant unilamellar vesicles (GUVs). Compared against DPPE-biotin, DPPE-cap-biotin, and DSPE-PEG2000-biotin lipids, the new dipalmityl-EGn-biotin lipids exhibited markedly enhanced partitioning into liquid ordered domains, achieving Kp of up to 7.3 with a decaethylene glycol spacer (DP-EG10-biotin). We further demonstrated biological relevance of the lipids with selective partitioning to lipid raft-like domains observed in giant plasma membrane vesicles (GPMVs) derived from mammalian cells. Our results found that the spacer group not only plays a pivotal role for designing lipids with phase selectivity but may also influence the structural order of the domain assemblies.

  10. Archaeological bone lipids as palaeodietary markers.

    Science.gov (United States)

    Colonese, André C; Farrell, Thomas; Lucquin, Alexandre; Firth, Daniel; Charlton, Sophy; Robson, Harry K; Alexander, Michelle; Craig, Oliver E

    2015-04-15

    Stable isotope analysis of archaeological and fossil bone samples can provide important insights into past environments, ecologies and diets. Previous studies have focused on stable carbon and nitrogen isotopes in bone collagen, or carbon isotopes in bone mineral (bioapatite). Carbon isotope analysis of lipids from archaeological bone has received much less attention, partly due to the lack of suitable methodologies allowing sufficient recovery of compounds for structural and isotopic characterisation. Here we show that lipids can be easily and reliably recovered from archaeological bone using a modified protocol, and that these provide complementary dietary information to other bone components. Human and animal bones were obtained from a variety of archaeological contexts. Lipids were sequentially extracted using solvent extraction (dichloromethane/methanol), followed by acidified methanol extraction (methanol/H2SO4). The lipids were then analysed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Appreciable amounts of endogenous lipid were recovered from archaeological bone. Importantly, a comparison between compound-specific and bulk collagen isotopic data shows that archaeological bone lipids reflect dietary input and can be used to distinguish between marine and terrestrial consumers, as well as between C3 and C4 plant consumers. Furthermore, the presence of essential fatty acids directly incorporated from diet to bone may provide additional palaeodietary information. Our findings suggest that archaeological bone lipids are a hitherto untapped resource of dietary information that offer additional insights to those gained from other isotopic analyses of bone. Copyright © 2015 John Wiley & Sons, Ltd.

  11. How proteins move lipids and lipids move proteins

    NARCIS (Netherlands)

    Sprong, H.|info:eu-repo/dai/nl/222364815; van der Sluijs, P.; van Meer, G.|info:eu-repo/dai/nl/068570368

    2001-01-01

    Cells determine the bilayer characteristics of different membranes by tightly controlling their lipid composition. Local changes in the physical properties of bilayers, in turn, allow membrane deformation, and facilitate vesicle budding and fusion. Moreover, specific lipids at specific locations

  12. Marine lipids and the bioavailability of omega-3 fatty acids

    DEFF Research Database (Denmark)

    Mu, Huiling; Müllertz, Anette

    2015-01-01

    Marine lipids are enriched with omega-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3 fatty acids are important membrane lipids and have many recognized health benefits, the bioavailability of these fatty acids can therefore be important for achieving...... of omega-3 fatty acids has been reported to be affected by several factors; among the important factors were the digestion and absorption processes of omega-3 containing lipids in the gastrointestinal tract. Both lipid structures and food structures can affect the bioavailability of omega-3 fatty acids....... Human studies have shown that the relative bioavailability of omega-3 fatty acids from fish oil (triglyceride formulation) was similar to that from fish, whereas lower relative bioavailability was observed from fatty acid ethyl ester (FAEE) formulation in comparison with other lipid formulations...

  13. Marine lipids and the bioavailability of omega-3 fatty acids

    DEFF Research Database (Denmark)

    Mu, Huiling; Müllertz, Anette

    2015-01-01

    Marine lipids are enriched with omega-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3 fatty acids are important membrane lipids and have many recognized health benefits, the bioavailability of these fatty acids can therefore be important for achieving...... the beneficial healthy effects. As important membrane lipids, the incorporation and depletion kinetics of EPA and DHA in biological membranes have been found to be different, DHA was depleted slowly from both erythrocyte and plasma membranes due to the slow re-synthesis of DHA in the body. The bioavailability...... of omega-3 fatty acids has been reported to be affected by several factors; among the important factors were the digestion and absorption processes of omega-3 containing lipids in the gastrointestinal tract. Both lipid structures and food structures can affect the bioavailability of omega-3 fatty acids...

  14. Structure and dynamics of H{sub 2}O vis-á-vis phenylalanine recognition at a DPPC lipid membrane via interfacial H-bond types: Insights from polarized FT-IRRAS and ADMP simulations

    Energy Technology Data Exchange (ETDEWEB)

    Sarangi, Nirod Kumar; Ramesh, Nivarthi; Patnaik, Archita [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India)

    2015-01-14

    Preferential and enantioselective interactions of L-/D-Phenylalanine (L-Phe and D-Phe) and butoxycarbonyl-protected L-/D-Phenylalanine (LPA and DPA) as guest with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (L-DPPC) as host were tapped by using real time Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS). Polarization-modulated FT-IRRAS of DPPC monolayers above the phenylalanine modified subphases depicted fine structure/conformation differences under considerations of controlled 2D surface pressure. Selective molecular recognition of D-enantiomer over L-enantiomer driven by the DPPC head group via H-bonding and electrostatic interactions was evident spectroscopically. Accordingly, binding constants (K) of 145, 346, 28, and 56 M{sup −1} for LPA, DPA, L-Phe, and D-Phe, respectively, were estimated. The real time FT-IRRAS water bands were strictly conformation sensitive. The effect of micro-solvation on the structure and stability of the 1:1 diastereomeric L-lipid⋯, LPA/DPA and L-lipid⋯, (L/D)-Phe adducts was investigated with the aid of Atom-centered Density Matrix Propagation (ADMP), a first principle quantum mechanical molecular dynamics approach. The phosphodiester fragment was the primary site of hydration where specific solvent interactions were simulated through single- and triple- “water-phosphate” interactions, as water cluster’s “tetrahedral dice” to a “trimeric motif” transformation as a partial de-clusterization was evident. Under all the hydration patterns considered in both static and dynamic descriptions of density functional theory, L-lipid/D-amino acid enantiomer adducts continued to be stable structures while in dynamic systems, water rearranged without getting “squeezed-out” in the process of recognition. In spite of the challenging computational realm of this multiscale problem, the ADMP simulated molecular interactions complying with polarized vibrational spectroscopy unraveled a novel route to chiral

  15. Bioactive lipids in kidney physiology and pathophysiology

    Directory of Open Access Journals (Sweden)

    Daria Sałata

    2014-01-01

    Full Text Available Lipids not only have structural functions, but also play an important role as signaling and regulatory molecules and participate in many cellular processes such as proliferation, differentiation, migration, and apoptosis. Bioactive lipids act both as extracellular mediators, which are associated with receptors on the surface of cells, and intracellular mediators triggering different signal pathways. They are present and active in physiological conditions, and are also involved in the pathogenesis of inflammation, asthma, cancer, diabetes, and hypertension. Bioactive lipids such as derivatives of arachidonic acid and sphingolipids have an important role in renal development, physiology and in many renal diseases. Some of them are potential indicators of kidney damage degree and/or function of the transplanted kidneys.

  16. Status of Lipid Profile in Pregnancy

    Directory of Open Access Journals (Sweden)

    Deepak Parchwani

    2011-02-01

    Full Text Available Pregnancy greatly increases demand for metabolic fuels that are needed for growth and development of the fetus and its support structures. The total gestation related energy cost has been estimated at approximately 83000 kcal. The major change in energy expenditure and in the accumulation of fat occurs at different times during pregnancy. In the current study a serial study of serum lipids was performed in a group of women throughout gestation and six weeks post partum while they were having their usual diet and unrestricted daily activity. The control group consisted of non pregnant healthy women of child bearing age. Data was analyzed by SPSS software. All lipid fractions underwent a gradual and persistent rise throughout pregnancy with the exception of HDL-C i.e. a progressive rise was observed in serum total cholesterol, serum triglyceride, serum VLDL and LDL-C as pregnancy advances, while serum HDL-C showed a biphasic pattern, as initial rise and then decline in later third of pregnancy. However, during early pregnancy the values of all lipid fractions do not differ significantly from those for normal non pregnant controls. No significant difference was observed in vegetarian and non-vegetarian group in any of the lipid fractions in different trimester of pregnancy—so diet had no significant influence on lipid synthesis during pregnancy. [National J of Med Res 2011; 1(1.000: 10-12

  17. Role of Neutral Lipids in Tear Fluid Lipid Layer: Coarse-Grained Simulation Study

    DEFF Research Database (Denmark)

    Telenius, J.; Koivuniemi, A.; Kulovesi, P.

    2012-01-01

    Tear fluid lipid layer (TFLL) residing at the air-water interface of tears has been recognized to play an important role in the development of dry eye syndrome. Yet, the composition, structure, and mechanical properties of TFLL are only partly known. Here, we report results of coarse-grained simu......Tear fluid lipid layer (TFLL) residing at the air-water interface of tears has been recognized to play an important role in the development of dry eye syndrome. Yet, the composition, structure, and mechanical properties of TFLL are only partly known. Here, we report results of coarse...

  18. Lipid Therapy for Intoxications

    NARCIS (Netherlands)

    Robben, Joris Henricus; Dijkman, Marieke Annet

    2017-01-01

    This review discusses the use of intravenous lipid emulsion (ILE) in the treatment of intoxications with lipophilic agents in veterinary medicine. Despite growing scientific evidence that ILE has merit in the treatment of certain poisonings, there is still uncertainty on the optimal composition of t

  19. Lipids in cheese

    Science.gov (United States)

    Lipids are present in cheese at levels above 20 percent and are analyzed by several techniques. Scanning electron microscopy and confocal laser scanning microscopy are used to examine the microstructure, gas chromatography is employed to look at fatty acid composition, and differential scanning cal...

  20. Lipid Therapy for Intoxications

    NARCIS (Netherlands)

    Robben, Joris Henricus; Dijkman, Marieke Annet

    2017-01-01

    This review discusses the use of intravenous lipid emulsion (ILE) in the treatment of intoxications with lipophilic agents in veterinary medicine. Despite growing scientific evidence that ILE has merit in the treatment of certain poisonings, there is still uncertainty on the optimal composition of t

  1. The lipid-rich core region of human atherosclerotic fibrous plaques. Prevalence of small lipid droplets and vesicles by electron microscopy.

    Science.gov (United States)

    Guyton, J. R.; Klemp, K. F.

    1989-01-01

    Abundant extracellular lipid deposits are associated with cell necrosis and tissue weakening in the core region of human atherosclerotic fibrous plaques. The ultrastructural morphology of the core region, previously undefined because of lipid extraction artifacts, was studied with the aid of new osmium-thiocarbohydrazide-osmium and osmium-tannic acid-paraphenylenediamine sequences for tissue processing. Small droplets of neutral lipid (30 to 400 nm profile diameter) and lipid vesicles with aqueous centers accounted for more than 90% of the area occupied by lipid-rich structures in the core region. No foam cells were present. Cholesterol crystals, lipid droplets of a size similar to those in foam cells (0.4 to 6 mu), and larger neutral lipid deposits (greater than 6 mu) together occupied less than 10% of the total area of lipid structures. Abundant lipid vesicles were associated with the nearby presence of cholesterol crystals, whereas small lipid droplets were predominant in areas without crystals. Many droplets had surface defects in the form of pits and vesicular blebs. These morphologic findings are explained most concisely by postulating direct accumulation of extracellular lipid from interstitial lipoproteins as a major process in core region formation. Moreover, a dynamic state of ongoing physical/metabolic transformation of extracellular lipid deposits is suggested. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 Figure 8 Figure 9 PMID:2646938

  2. Amphotericin B Lipid Complex Injection

    Science.gov (United States)

    Amphotericin B lipid complex injection is used to treat serious, possibly life-threatening fungal infections in people who did not respond ... to tolerate conventional amphotericin B therapy. Amphotericin B lipid complex injection is in a class of medications ...

  3. Structure and sequence analyses of Bacteroides proteins BVU_4064 and BF1687 reveal presence of two novel predominantly-beta domains, predicted to be involved in lipid and cell surface interactions.

    Science.gov (United States)

    Natarajan, Padmaja; Punta, Marco; Kumar, Abhinav; Yeh, Andrew P; Godzik, Adam; Aravind, L

    2015-01-16

    N-terminal domains of BVU_4064 and BF1687 proteins from Bacteroides vulgatus and Bacteroides fragilis respectively are members of the Pfam family PF12985 (DUF3869). Proteins containing a domain from this family can be found in most Bacteroides species and, in large numbers, in all human gut microbiome samples. Both BVU_4064 and BF1687 proteins have a consensus lipobox motif implying they are anchored to the membrane, but their functions are otherwise unknown. The C-terminal half of BVU_4064 is assigned to protein family PF12986 (DUF3870); the equivalent part of BF1687 was unclassified. Crystal structures of both BVU_4064 and BF1687 proteins, solved at the JCSG center, show strikingly similar three-dimensional structures. The main difference between the two is that the two domains in the BVU_4064 protein are connected by a short linker, as opposed to a longer insertion made of 4 helices placed linearly along with a strand that is added to the C-terminal domain in the BF1687 protein. The N-terminal domain in both proteins, corresponding to the PF12985 (DUF3869) domain is a β-sandwich with pre-albumin-like fold, found in many proteins belonging to the Transthyretin clan of Pfam. The structures of C-terminal domains of both proteins, corresponding to the PF12986 (DUF3870) domain in BVU_4064 protein and an unclassified domain in the BF1687 protein, show significant structural similarity to bacterial pore-forming toxins. A helix in this domain is in an analogous position to a loop connecting the second and third strands in the toxin structures, where this loop is implicated to play a role in the toxin insertion into the host cell membrane. The same helix also points to the groove between the N- and C-terminal domains that are loosely held together by hydrophobic and hydrogen bond interactions. The presence of several conserved residues in this region together with these structural determinants could make it a functionally important region in these proteins. Structural

  4. Counterion-mediated pattern formation in membranes containing anionic lipids.

    Science.gov (United States)

    Slochower, David R; Wang, Yu-Hsiu; Tourdot, Richard W; Radhakrishnan, Ravi; Janmey, Paul A

    2014-06-01

    Most lipid components of cell membranes are either neutral, like cholesterol, or zwitterionic, like phosphatidylcholine and sphingomyelin. Very few lipids, such as sphingosine, are cationic at physiological pH. These generally interact only transiently with the lipid bilayer, and their synthetic analogs are often designed to destabilize the membrane for drug or DNA delivery. However, anionic lipids are common in both eukaryotic and prokaryotic cell membranes. The net charge per anionic phospholipid ranges from -1 for the most abundant anionic lipids such as phosphatidylserine, to near -7 for phosphatidylinositol 3,4,5 trisphosphate, although the effective charge depends on many environmental factors. Anionic phospholipids and other negatively charged lipids such as lipopolysaccharides are not randomly distributed in the lipid bilayer, but are highly restricted to specific leaflets of the bilayer and to regions near transmembrane proteins or other organized structures within the plane of the membrane. This review highlights some recent evidence that counterions, in the form of monovalent or divalent metal ions, polyamines, or cationic protein domains, have a large influence on the lateral distribution of anionic lipids within the membrane, and that lateral demixing of anionic lipids has effects on membrane curvature and protein function that are important for biological control. Copyright © 2014. Published by Elsevier B.V.

  5. Thermal stability of ladderane lipids as determined by hydrous pyrolysis

    Science.gov (United States)

    Jaeschke, A.; Lewan, M.D.; Hopmans, E.C.; Schouten, S.; Sinninghe, Damste J.S.

    2008-01-01

    Anaerobic ammonium oxidation (anammox) has been recognized as a major process resulting in loss of fixed inorganic nitrogen in the marine environment. Ladderane lipids, membrane lipids unique to anammox bacteria, have been used as markers for the detection of anammox in marine settings. However, the fate of ladderane lipids after sediment burial and maturation is unknown. In this study, anammox bacterial cell material was artificially matured by hydrous pyrolysis at constant temperatures ranging from 120 to 365 ??C for 72 h to study the stability of ladderane lipids during progressive dia- and catagenesis. HPLC-MS/MS analysis revealed that structural alterations of ladderane lipids already occurred at 120 ??C. At temperatures >140 ??C, ladderane lipids were absent and only more thermally stable products could be detected, i.e., ladderane derivatives in which some of the cyclobutane rings were opened. These diagenetic products of ladderane lipids were still detectable up to temperatures of 260 ??C using GC-MS. Thus, ladderane lipids are unlikely to occur in ancient sediments and sedimentary rocks, but specific diagenetic products of ladderane lipids will likely be present in sediments and sedimentary rocks of relatively low maturity (i.e., C31 hopane 22S/(22S + 22R) ratio 0.5). ?? 2008 Elsevier Ltd.

  6. Electroporation of heterogeneous lipid membranes.

    Science.gov (United States)

    Reigada, Ramon

    2014-03-01

    Electroporation is the basis for the transfection of genetic material and for drug delivery to cells, including electrochemotherapy for cancer. By means of molecular dynamics many aspects of membrane electroporation have been unveiled at the molecular detail in simple, homogeneous, lipid bilayers. However, the correspondence of these findings \\with the process happening in cell membranes requires, at least, the consideration of laterally structured membranes. Here, I present a systematic molecular dynamics study of bilayers composed of different liquid-ordered and liquid-disordered lipid phases subjected to a transversal electric field. The simulations reveal two significant results. First, the electric field mainly affects the properties of the disordered phases, so that electroporation takes place in these membrane regions. Second, the smaller the disordered domains are, the faster they become electroporated. These findings may have a relevant significance in the experimental application of cell electroporation in vivo since it implies that electro-induced and pore-mediated transport processes occur in particularly small disordered domains of the plasma membrane, thus locally affecting only specific regions of the cell.

  7. System lipidic distress-syndrome at traumatic illness

    Directory of Open Access Journals (Sweden)

    A. P. Vlasov

    2013-01-01

    Full Text Available The purpose of work was studying of a role of systemic lipid metabolism disturbances in a pathogenesis of homeostasis disorders in the early posttraumatic period at fractures of pelvic bones in experiment and clinic. Pilot and clinical studies are put in a basis of work with application of the techniques estimating structure phospholipid membranes of erythrocytes, cells of a liver, kidneys, heart, lungs, and also intensity of the processes participating in a regulation of a lipid metabolism. Results. It is established that at a pelvic trauma change of lipids structure arise not only in a blood, but also other tissues structures (a liver, kidneys, lungs, heart that is caused by activization of phosfolipaze systems, an intensification of lipids peroxidation process. There is a systemic lipid distress syndrome. The arisen changes - one of significant in a pathogenesis of traumatic illness. At modification of lipid structure of a biomembrane the morphological and functional condition of a cell starts suffering. It is substrate of emergence of disregulation pathologies. The received scientific facts can be the base for intelligent medical actions for the purpose of the prevention of emergence of a "favorable" background of disregulation conditions by vectorial impact on one of its main pathogenetic links - a systemic lipide distress syndrome.

  8. The solution structure of the soluble form of the lipid-modified azurin from Neisseria gonorrhoeae, the electron donor of cytochrome c peroxidase.

    Science.gov (United States)

    Nóbrega, Cláudia S; Saraiva, Ivo H; Carreira, Cíntia; Devreese, Bart; Matzapetakis, Manolis; Pauleta, Sofia R

    2016-02-01

    Neisseria gonorrhoeae colonizes the genitourinary track, and in these environments, especially in the female host, the bacteria are subjected to low levels of oxygen, and reactive oxygen and nitrosyl species. Here, the biochemical characterization of N. gonorrhoeae Laz is presented, as well as, the solution structure of its soluble domain determined by NMR. N. gonorrhoeae Laz is a type 1 copper protein of the azurin-family based on its spectroscopic properties and structure, with a redox potential of 277±5 mV, at pH7.0, that behaves as a monomer in solution. The globular Laz soluble domain adopts the Greek-key motif, with the copper center located at one end of the β-barrel coordinated by Gly48, His49, Cys113, His118 and Met122, in a distorted trigonal geometry. The edge of the His118 imidazole ring is water exposed, in a surface that is proposed to be involved in the interaction with its redox partners. The heterologously expressed Laz was shown to be a competent electron donor to N. gonorrhoeae cytochrome c peroxidase. This is an evidence for its involvement in the mechanism of protection against hydrogen peroxide generated by neighboring lactobacilli in the host environment.

  9. Lipid nanotube or nanowire sensor

    Science.gov (United States)

    Noy, Aleksandr; Bakajin, Olgica; Letant, Sonia; Stadermann, Michael; Artyukhin, Alexander B.

    2009-06-09

    A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

  10. LipidPioneer : A Comprehensive User-Generated Exact Mass Template for Lipidomics

    Science.gov (United States)

    Ulmer, Candice Z.; Koelmel, Jeremy P.; Ragland, Jared M.; Garrett, Timothy J.; Bowden, John A.

    2017-03-01

    Lipidomics, the comprehensive measurement of lipid species in a biological system, has promising potential in biomarker discovery and disease etiology elucidation. Advances in chromatographic separation, mass spectrometric techniques, and novel substrate applications continue to expand the number of lipid species observed. The total number and type of lipid species detected in a given sample are generally indicative of the sample matrix examined (e.g., serum, plasma, cells, bacteria, tissue, etc.). Current exact mass lipid libraries are static and represent the most commonly analyzed matrices. It is common practice for users to manually curate their own lists of lipid species and adduct masses; however, this process is time-consuming. LipidPioneer, an interactive template, can be used to generate exact masses and molecular formulas of lipid species that may be encountered in the mass spectrometric analysis of lipid profiles. Over 60 lipid classes are present in the LipidPioneer template and include several unique lipid species, such as ether-linked lipids and lipid oxidation products. In the template, users can add any fatty acyl constituents without limitation in the number of carbons or degrees of unsaturation. LipidPioneer accepts naming using the lipid class level (sum composition) and the LIPID MAPS notation for fatty acyl structure level. In addition to lipid identification, user-generated lipid m/z values can be used to develop inclusion lists for targeted fragmentation experiments. Resulting lipid names and m/z values can be imported into software such as MZmine or Compound Discoverer to automate exact mass searching and isotopic pattern matching across experimental data.

  11. LipidPioneer : A Comprehensive User-Generated Exact Mass Template for Lipidomics

    Science.gov (United States)

    Ulmer, Candice Z.; Koelmel, Jeremy P.; Ragland, Jared M.; Garrett, Timothy J.; Bowden, John A.

    2017-01-01

    Lipidomics, the comprehensive measurement of lipid species in a biological system, has promising potential in biomarker discovery and disease etiology elucidation. Advances in chromatographic separation, mass spectrometric techniques, and novel substrate applications continue to expand the number of lipid species observed. The total number and type of lipid species detected in a given sample are generally indicative of the sample matrix examined (e.g., serum, plasma, cells, bacteria, tissue, etc.). Current exact mass lipid libraries are static and represent the most commonly analyzed matrices. It is common practice for users to manually curate their own lists of lipid species and adduct masses; however, this process is time-consuming. LipidPioneer, an interactive template, can be used to generate exact masses and molecular formulas of lipid species that may be encountered in the mass spectrometric analysis of lipid profiles. Over 60 lipid classes are present in the LipidPioneer template and include several unique lipid species, such as ether-linked lipids and lipid oxidation products. In the template, users can add any fatty acyl constituents without limitation in the number of carbons or degrees of unsaturation. LipidPioneer accepts naming using the lipid class level (sum composition) and the LIPID MAPS notation for fatty acyl structure level. In addition to lipid identification, user-generated lipid m/z values can be used to develop inclusion lists for targeted fragmentation experiments. Resulting lipid names and m/z values can be imported into software such as MZmine or Compound Discoverer to automate exact mass searching and isotopic pattern matching across experimental data.

  12. Lanolin-derived lipid mixtures mimic closely the lipid composition and organization of vernix caseosa lipids.

    Science.gov (United States)

    Rissmann, Robert; Oudshoorn, Marion H M; Kocks, Elise; Hennink, Wim E; Ponec, Maria; Bouwstra, Joke A

    2008-10-01

    The aim of the present study was to use semi-synthetic lipid mixtures to mimic the complex lipid composition, organization and thermotropic behaviour of vernix caseosa (VC) lipids. As VC shows multiple protecting and barrier supporting properties before and after birth, it is suggested that a VC substitute could be an innovative barrier cream for barrier deficient skin. Lanolin was selected as the source of the branched chain sterol esters and wax esters--the main lipid classes of VC. Different lipid fractions were isolated from lanolin and subsequently mixed with squalene, triglycerides, cholesterol, ceramides and fatty acids to generate semi-synthetic lipid mixtures that mimic the lipid composition of VC, as established by high-performance thin-layer chromatography. Differential scanning calorimetry and Fourier transform infrared spectroscopy investigations revealed that triglycerides play an important role in the (lateral) lipid organization and thermotropic behaviour of the synthetic lipid mixtures. Excellent resemblance of VC lipids was obtained when adding unsaturated triglycerides. Moreover, these lipid mixtures showed similar long range ordering as VC. The optimal lipid mixture was evaluated on tape-stripped hairless mouse skin in vivo. The rate of barrier recovery was increased and comparable to VC lipid treatment.

  13. Responses of Transmembrane Peptide and Lipid Chains to Hydrophobic Mismatch

    Institute of Scientific and Technical Information of China (English)

    YANG Lei; LI Jian-tao; QI Hai-yan; LI Fei

    2012-01-01

    Hydrophobic mismatch between the hydrophobic length of membrane proteins and hydrophobic thickness of membranes is a crucial factor in controlling protein function and assembly.We combined fluorescence with circular dichroism(CD) and attenu