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Chemistry and Physics of Lipids

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https://www.readbyqxmd.com/read/28209390/liquid-crystal-based-capillary-sensory-platform-for-the-detection-of-bile-acids
#1
Hyeong Jin Kim, Chang-Hyun Jang
Bile acids directly related to liver and intestinal function are used as indicators of hepatobiliary and intestinal diseases. Here, we have designed and realized a capillary sensory platform for the detection of bile acids using liquid crystals (LCs). LC droplets confined in micro-capillaries are homeotropically aligned at the surfactant-packed LC/aqueous interface. However, the competitive adsorption of bile acids disrupts the surfactant packing at this interface and triggers the orientational transition of the LC droplets from homeotropic to planar at the interface, followed by changes in optical images captured by polarized light microscopy...
February 13, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28202334/synthesis-of-specifically-deuterated-ceramide-ap-c18-and-its-biophysical-characterization-using-neutron-diffraction
#2
Stefan Sonnenberger, Adina Eichner, Thomas Hauß, Annett Schroeter, Reinhard H H Neubert, Bodo Dobner
The very heterogeneous group of ceramides is known to be mandatory for proper barrier functions of the outermost layer of mammalian skin, referred to as stratum corneum (SC). The synthesis of a specifically deuterated ceramide [AP]-C18 variant is described. The synthesized ceramide contains the racemic forms of the α hydroxy fatty acid. For the biophysical implementation, the received diastereomeric ceramide was applied in a neutron diffraction experiment. Therefore, a SC lipid model membrane was prepared containing the described ceramide (CER), cholesterol (CHOL), stearic acid (SA), and cholesterol sulfate (ChS) in a ratio of 55/25/15/5wt%...
February 12, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28188720/the-effect-of-non-deuterated-and-deuterated-isopropyl-myristate-on-the-thermodynamical-and-structural-behavior-of-a-2d-stratum-corneum-model-with-ceramide-ap
#3
J S L Oliveira, S Lange, B Dobner, G Brezesinski
Isopropyl myristate (IPM) is a widely used penetration enhancer in pharmaceutical formulations, however, its mechanism of action on a molecular scale is still not completely understood. Previous work using a quaternary Stratum Corneum (SC) lipid model in bulk suggested the incorporation of isopropyl myristate into the SC lipid matrix, phase separation, and perturbation of the multilamellar lipid assembly. Here, we used 2D Langmuir monolayers of a ternary SC lipid model, containing ceramide AP C18:18, stearic acid and cholesterol in a molar ratio of [1:1:0...
February 7, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28174017/propagation-rate-constants-for-the-peroxidation-of-sterols-on-the-biosynthetic-pathway-to-cholesterol
#4
Connor R Lamberson, Hubert Muchalski, Kari B McDuffee, Keri A Tallman, Libin Xu, Ned A Porter
The free radical chain autoxidation of cholesterol and the oxidation products formed, i.e. oxysterols, have been the focus of intensive study for decades. The peroxidation of sterol precursors to cholesterol such as 7-dehydrocholesterol (7-DHC) and desmosterol as well as their oxysterols has received less attention. The peroxidation of these sterol precursors can become important under circumstances in which genetic conditions or exposures to small molecules leads to an increase of these biosynthetic intermediates in tissues and fluids...
February 5, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28163064/thermal-stability-of-plant-sterols-and-formation-of-their-oxidation-products-in-vegetable-oils-and-margarines-upon-controlled-heating
#5
Yuguang Lin, Diny Knol, Iris Valk, Vincent van Andel, Silvia Friedrichs, Dieter Lütjohann, Karel Hrncirik, Elke A Trautwein
Fat-based products like vegetable oils and margarines are commonly used for cooking, which may enhance oxidation of plant sterols (PS) present therein, leading to the formation of PS oxidation products (POP). The present study aims to assess the kinetics of POP formation in six different fat-based products. Vegetable oils and margarines without and with added PS (7.5-7.6% w/w) in esterified form were heated in a Petri-dish at temperatures of 150, 180 and 210°C for 8, 12 and 16min. PS and POP were analysed using GC-FID and GC-MS-SIM, respectively...
February 2, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28109756/membrane-cholesterol-oxidation-in-live-cells-enhances-the-function-of-serotonin1a-receptors
#6
Md Jafurulla, Aswan Nalli, Amitabha Chattopadhyay
The serotonin1A (5-HT1A) receptor is an important neurotransmitter receptor that belongs to the G protein-coupled receptor (GPCR) family. It is implicated in a variety of cognitive and behavioral functions and serves as an important drug target for neuropsychiatric disorders such as anxiety and depression. Previous work from our laboratory has demonstrated that membrane cholesterol plays an important role in the function of the serotonin1A receptor. Our earlier results highlighted several structural features of cholesterol essential for receptor function...
January 18, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28104377/changes-in-lipid-bilayer-structure-caused-by-the-helix-to-sheet-transition-of-an-hiv-1-gp41-fusion-peptide-derivative
#7
William T Heller, Durgesh K Rai
HIV-1, like other enveloped viruses, undergoes fusion with the cell membrane to infect it. Viral coat proteins are thought to bind the virus to the membrane and actively fuse the viral and cellular membranes together. The actual molecular mechanism of fusion is challenging to visualize, resulting in the use of model systems. Here, the bilayer curvature modifying properties of a synthetic variant of the HIV-1 gp41 fusion peptide with lipid bilayer vesicles composed of a mixture of dimyristoyl phosphatidylcholine (DMPC) and dimyristoyl phosphatidylserine (DMPS) were studied...
January 16, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28104376/lipidomic-profile-of-gm95-cell-death-induced-by-clostridium-perfringens-alpha-toxin
#8
Marco M Manni, Juan G Valero, Miriam Pérez-Cormenzana, Ainara Cano, Cristina Alonso, Félix M Goñi
Clostridium perfringens alpha-toxin (ATX) is considered as a prototype of cytotoxic bacterial phospholipases C, and is the major virulence factor in C. perfringens-induced gas gangrene. It is known that, depending on the dose, ATX causes membrane disruption and cytolysis or only limited hydrolysis of its substrates. In the latter case, toxin activity leads to the unregulated generation of bioactive lipids that can ultimately induce cell death. We have characterized apoptosis and necrosis in highly ATX-sensitive, ganglioside-deficient cells exposed to different concentrations of ATX and we have studied the lipidomic profile of cells treated with ATX as compared to native cells to detect the main changes in the lipidomic profile and the possible involvement of lipid signals in cell death...
January 16, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28088325/molecular-dynamics-simulations-of-ternary-lipid-bilayers-containing-plant-sterol-and-glucosylceramide
#9
Shiva Emami, Sodeif Azadmard-Damirchi, Seyed Hadi Peighambardoust, Javad Hesari, Hadi Valizadeh, Roland Faller
An atomic-level molecular dynamics simulation was carried out to study the effects of a plant sterol (sitosterol) and glucosylceramide (GlcCer) on a 1,2-dilinoleoylposphocholine (DLiPC) membrane. Initially, a membrane containing 50mol% sitosterol was compared with that containing the same ratio of cholesterol. These simulations showed differential condensing and ordering effects of sitosterol and cholesterol, with cholesterol being slightly more efficient than sitosterol in packing the membrane more tightly to a liquid ordered phase...
January 11, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28069393/surface-enhanced-raman-spectroscopy-of-self-assembled-layers-of-lipid-molecules-on-nanostructured-au-and-ag-substrates
#10
Nora Slekiene, Lina Ramanauskaite, Valentinas Snitka
In this work surface enhanced Raman spectroscopy (SERS) has been used for the investigation of the self-assembled layers of lipid molecules (SALLMs) deposited on the nanostructured Au and Ag surfaces. The SALLMs were prepared from one part of 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) and four parts of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipids. The synthesis of Au and Ag SERS substrates was based on the direct gold and silver ions reduction onto HF etched silicon wafers. Au SERS substrates were not suitable for the formation of SALLMs because of the inappropriate contact angle of surface...
January 6, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28063839/a-comparison-of-pc-oxidation-products-as-detected-by-maldi-tof-and-esi-it-mass-spectrometry
#11
Kathrin M Engel, Jürgen Schiller
Oxidized (phospho)lipids are of paramount interest for different reasons: besides their in vivo relevance as markers of inflammatory diseases, they are often needed in the laboratory to study the response of selected cells to oxidized lipids. Mass spectrometry (MS) is nowadays one of the most powerful methods to identify lipid oxidation products. Although MALDI and ESI MS are both widely used, it is so far not clear whether all potential phospholipid oxidation products can be detected by both methods This aspect will be studied here using NaMnO4-oxidized phosphatidylcholine 16:0/18:1 and 16:0/18:2 as simple, but reliable model systems...
January 4, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28062355/cerebrosides-extracellular-glycolipids-secreted-by-the-selective-lignin-degrading-fungus-ceriporiopsis-subvermispora
#12
Hiroshi Nishimura, Daisuke Yamaguchi, Takashi Watanabe
Ceriporiopsis subvermispora is a selective white-rot fungus that degrades lignin at a site far from the hyphae and extracellular enzymes, without intensive damage to the cellulose. In selective ligninolysis, low molecular mass metabolites play a principal role and amphipathic substances are involved to control the degradation and transport of hydrophobic aromatic molecules, including lignin and lipids; however, secretion of the amphipathic substances by this fungus has not been well understood, except for alk(en)yl itaconates called ceriporic acids, which have a weak amphiphilicity...
January 3, 2017: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28048967/the-pore-forming-capacity-of-sticholysin-i-in-dipalmitoyl-phosphatidyl-vesicles-is-tuned-by-osmotic-stress
#13
M Ahumada, C Calderon, E Lissi, C Alvarez, M E Lanio, F Pazos
The osmotic condition modulates the properties of liposomes, particularly those related to their stability and response to external agents such as membrane-active proteins or peptides. In a previous work, we have demonstrated that an osmotic shock can increase, per se, water influx/efflux and the exit of the fluorophore calcein entrapped in the aqueous pool of dipalmitoylphosphatidylcholine (DPPC) and DPPC:sphingomyelin (SM) large unilamellar vesicles (LUVs), suggesting a loss of integrity of the liposome bilayer...
December 31, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28043845/distributions-of-therapeutically-promising-neurosteroids-in-cellular-membranes
#14
Kamila Riedlová, Michaela Nekardová, Petr Kačer, Kamila Syslová, Mario Vazdar, Pavel Jungwirth, Eva Kudová, Lukasz Cwiklik
Interactions of two neurosteroids, inhibiting membrane-bound N-Methyl-d-aspartate receptors, with phospholipid membranes are studied. Namely, endogenous pregnanolone sulfate is compared with pregnanolone glutamate, the latter being a novel synthetic steroidal inhibitor of these receptors with potential pharmaceutical use. Molecular-level details of steroid-phospholipid membranes interactions are scrutinized employing molecular dynamics simulations supported by quantum chemical calculations to assess steroid lipophilicity...
December 30, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/27986474/phosphatidyl-hydroxytyrosol-and-phosphatidyl-tyrosol-bilayer-properties
#15
Kervin O Evans, David L Compton
Hydroxytyrosol and tyrosol phospholipids were enzymatically synthesized and investigated for their bilayer properties. Dynamic light scattering demonstrated that hand extrusion at 100nm consistently resulted in liposomes of nearly 85nm diameter for both phosphatidyl-hydroxytyrosol (DOPHT) and phosphatidyl-tyrosol (DOPT). Transmission electron microscopy showed DOPT and DOPHT liposomes extruded at 100-nm to be spherical and non-distinctive from one another. Zeta potential measurements resulted in surface charges<-25mV, demonstrating both DOPT and DOPHT form highly stable liposomes...
December 14, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/27964891/formation-of-hybrid-bilayers-on-silanized-thin-film-ti-electrode
#16
A Valiūnienė, T Petrulionienė, I Balevičiūtė, L Mikoliūnaitė, G Valinčius
Phospholipid bilayer membranes are essential elements of living organisms as they form boundaries between the intracellular cytoplasm and the extracellular environment, as well as organelles. In this work we report on our attempts to assemble artificial phospholipid bilayer model membranes on Ti surface. To provide hydrophobic cushion for phospholipids, the surface of a thin-film Ti electrode was initially functionalized with trichloro(octadecyl)silane (OTS). Increased hydrophobicity of the solid support allowed vesicle fusion and the formation of a hybrid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer, as probed by the electrochemical impedance spectroscopy (EIS), contact angle measurements (CA) also by the Fourier transform-infrared (FT-IR) spectroscopy, spectroscopic ellipsometry (SE) and atomic force microscopy (AFM)...
December 10, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/27964890/chemoenzymatic-synthesis-of-fluorogenic-phospholipids-and-evaluation-in-assays-of-phospholipases-a-c-and-d
#17
Mathilde S Piel, Günther H J Peters, Jesper Brask
Phospholipases are ubiquitous in nature and the target of significant research aiming at both their physiological roles and technical applications in e.g. the food industry. In the search for sensitive and selective phospholipase assays, we have focused on synthetic FRET (Förster resonance energy transfer) substrates. This has led to the development of a facile, easily scalable and low cost synthesis of fluorogenic phospholipids featuring the dansyl/dabcyl fluorophore/quencher-pair on the fatty acid ω-position and on the phosphatidylethanolamine head group, respectively...
December 10, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/27913102/membrane-permeabilization-induced-by-triton-x-100-the-role-of-membrane-phase-state-and-edge-tension
#18
Bruno Mattei, Rafael B Lira, Katia R Perez, Karin A Riske
Detergents are widely used to solubilize and separate biomembrane components. It is therefore relevant to study and understand the mechanistic details underlying detergent-lipid interactions using biomimetic systems. Here, we have investigated in detail the process of membrane permeabilization and the nature of pores induced by sub-solubilizing concentrations of the detergent Triton X-100 (TX-100) in bilayers composed of palmitoyl oleoyl phosphatidylcholine (POPC), sphingomyelin (SM) and binary mixtures of these phospholipids with 30 mol% cholesterol (chol)...
November 29, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/27894769/identification-of-molecular-species-of-monoalkyldiacylglycerol-from-the-squid-berryteuthis-magister-using-liquid-chromatography-apci-high-resolution-mass-spectrometry
#19
Viacheslav G Rybin, Andrey B Imbs, Darja A Demidkova, Ekaterina V Ermolenko
Monoalkyldiacylglycerol (MADAG) is an important lipid class in mollusks, corals, starfishes, and some species of zooplankton. Up to 80% of liver oils of squids and sharks are comprised of MADAG. Except for one fish species, there are no data on the composition of MADAG molecular species of marine organisms. The molecular species of MADAG obtained from digestive glands of the deep-sea squid Berryteuthis magister were identified. High-performance liquid chromatography (HPLC) and tandem high-resolution mass spectrometry (HRMS) with atmospheric pressure chemical ionization (APCI) were applied...
November 25, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/27956132/characterization-of-the-structure-of-lipodisq-nanoparticles-in-the-presence-of-kcne1-by-dynamic-light-scattering-and-transmission-electron-microscopy
#20
Rongfu Zhang, Indra D Sahu, Avnika P Bali, Carole Dabney-Smith, Gary A Lorigan
A recently developed membrane mimetic system called styrene maleic acid lipid particles (SMALPs) or lipodisq nanoparticles has shown to possess significant potential for biophysical studies of membrane proteins. This new nanoparticle system is composed of lipids encircled by SMA copolymers. Previous studies showed that SMA copolymers are capable of extracting membrane proteins directly from their native environments without the assistance of detergents. However, a full structural characterization of this promising membrane mimetic system is still lacking...
March 2017: Chemistry and Physics of Lipids
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