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Chemistry and Physics of Lipids

Kyu-Ho Song, Min-Young Lee, Chi-Hyeon Yoo, Song-I Lim, Bo-Young Choe
Proton magnetic resonance spectroscopy (MRS) with optimized relaxation time is an effective method to quantify hepatic fatty acid values and characterize steatosis. The aim of this study is to quantify the difference in hepatic lipid content with metabolic changes during the progression of steatosis by using localized MRS sequence with T2 relaxation time determination. Fatty liver disease was induced in C57BL/6N mice through a high-fat diet (HFD) of pellets containing 60% fat, 20% protein, and 20% carbohydrates...
January 11, 2018: Chemistry and Physics of Lipids
Mahantesh Jadhav, Rahul S Kalhapure, Sanjeev Rambharose, Chunderika Mocktar, Sanil Singh, Tetsuya Kodama, Thirumala Govender
The acidic environment at bacterial infection sites is a potential external stimulus for targeted antibiotic delivery. This paper reports new biocompatible pH-sensitive lipids (PSLs) with three hydrocarbon tails, and a head group with a secondary amine and carboxylate function for site-specific nano delivery of vancomycin (VCM). PSLs formed stable liposomes with mean vesicle diameters and polydispersity indices between 99.38 ± 6.59 nm to 105.60 ± 5.38 nm and 0.161 ± 0.003 to 0.219 ± 0...
January 2, 2018: Chemistry and Physics of Lipids
Marta Llorens-Fons, Esther Julián, Marina Luquin, Míriam Pérez-Trujillo
Mycobacterium smegmatis is often used to study the different components of mycobacterial cell wall. Mycolic acids are important components of mycobacterial cell wall that have been associated with virulence. Recently, a novel lipid containing mycolic acids has been described in M. smegmatis. However, some uncertainties regarding the structure of this molecule named mycolate ester wax have been reported. The objective of this work was to perform an in depth structural study of this molecule for its precise characterization...
December 29, 2017: Chemistry and Physics of Lipids
M Padariya, U Kalathiya, M Baginski
EmrE is a bacterial transporter protein that forms an anti-parallel homodimer with four transmembrane helices in each monomer. EmrE transports positively charged aromatic compounds, such as TPP+ and its derivatives. We performed molecular dynamics (MD) simulations of EmrE in complex with TPP+, MeTPP+, and MBTPP+ embedded in a membrane. The detailed molecular properties and interactions were analysed for all EmrE-ligand complexes. Our MD results identified that Lys22, Tyr40, Phe44, Trp45, and Trp63 formed potential π interactions with all three ligands and further confirmed the essential role of Glu14...
December 27, 2017: Chemistry and Physics of Lipids
Lina J Nåbo, Maciej Modzel, Kathiresan Krishnan, Douglas F Covey, Hideji Fujiwara, Daniel S Ory, Maria Szomek, Himanshu Khandelia, Daniel Wüstner, Jacob Kongsted
Oxysterols are oxidized derivatives of cholesterol with many important biological functions. Trafficking of oxysterols in and between cells is not well studied, largely due to the lack of appropriate oxysterol analogs. Intrinsically fluorescent oxysterols present a new route towards direct observation of intracellular oxysterol trafficking by fluorescence microscopy. We characterize the fluorescence properties of the existing fluorescent 25-hydroxycholesterol analog 25-hydroxycholestatrienol, and propose a new probe with an extended conjugated system...
December 26, 2017: Chemistry and Physics of Lipids
S Thirupathi Reddy, Sandeep Shrivastava, Amitabha Chattopadhyay
The molecular mechanism underlying the action of local anesthetics is still elusive. Phenylethanol (PEtOH) is an ingredient of essential oils with a rose-like odor and has been used as a local anesthetic. In this work, we have explored the effect of PEtOH on thermotropic behavior and organization of dipalmitoylphosphatidylcholine (DPPC) membranes utilizing differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS). Our results indicate that the phase transition temperature of DPPC exhibited decrease with increasing PEtOH concentration...
December 21, 2017: Chemistry and Physics of Lipids
Jenelle Umbsaar, Evan Kerek, Elmar J Prenner
Elevated levels of the essential trace metals cobalt and nickel are associated with a variety of toxic effects, which are not well-understood, and may involve interactions with the lipid membrane. Fluidity changes of biomimetic lipid membranes upon exposure to CoCl2 and NiCl2 were studied using the fluorescent probe Laurdan, which senses changes in environment polarity. Liposomes were prepared by extrusion in 20 mM HEPES + 100 mM NaCl at pH 7.4. Additionally, dynamic light scattering was used to monitor metal induced size changes of liposomes composed of: phosphatidic acid (PA), cardiolipin (CL), phosphatidylglycerol (PG), phosphatidylserine (PS), and phosphatidylcholine (PC), with saturated and unsaturated acyl chains...
December 13, 2017: Chemistry and Physics of Lipids
Masumi Villeneuve, Mihoko Tanaka, Natsumi Saito, Hiroyasu Sakamoto, Yoshiteru Hayami
Mixed micelles formed in a ternary-solute aqueous solution of NaOH, iron (III)-ethylenediamine-N,N,N',N'-tetraacetic acid complex (Fe-edta) and 1,2-diheptanoyl-sn-glycero-3-phosphatidyl choline (DHPC) were studied and compared with the mixed adsorbed film reported in Part I of this series to clarify the effect of the curvature of molecular assemblies on the interactions between their Fe-edta and DHPC constituents. The critical micelle concentrations (CMCs), surface tension at the CMC, and solution pH were measured as functions of the mole fractions of NaOH and DHPC...
December 11, 2017: Chemistry and Physics of Lipids
Masumi Villeneuve, Mihoko Tanaka, Natsumi Saito, Hiroyasu Sakamoto, Yoshiteru Hayami
We studied a ternary solutes aqueous solution of NaOH, iron (III)-ethylenediamine-N,N,N',N'-tetraacetic acid complex (Fe-edta), and 1,2-diheptanoyl-sn-glycero-3-phosphatidylcholine (DHPC)/air interface system to clarify the interactions between iron complexes and lipids with a phosphatidylcholine head group. The solution surface tension and pH were measured as functions of the total molality of NaOH, Fe-edta and DHPC, and the mole fractions of NaOH and DHPC. Rigorous thermodynamic equations were derived, in which the overall proton dissociation equilibria of Fe-edta and DHPC were taken into consideration, and applied to experimental data to obtain phase diagram of adsorption...
December 6, 2017: Chemistry and Physics of Lipids
Stefania Mele, Olle Söderman, Helena Ljusberg-Wahrén, Krister Thuresson, Maura Monduzzi, Tommy Nylander
The phase behavior in the oleic acid/sodium oleate/normal saline (0.15M NaCl aqueous solution) system has been determined. For this purpose visual inspection of samples between crossed polarizers, and Small Angle X-ray diffraction was used to identify the various phases and their unit cell dimensions. A rich phase behavior was observed for the ternary system, featuring reverse micellar, micellar cubic, hexagonal, and cubic phases, and large regions with lamellar phases. As expected the ratio the 'oleic acid/sodium oleate' determines the pH and as a consequence the phase behavior...
December 1, 2017: Chemistry and Physics of Lipids
Danijela Bakarić, Dražen Petrov, Yamuna Kunhi Mouvenchery, Stefan Heiβler, Chris Oostenbrink, Gabriele E Schaumann
Disaccharides play an important role in survival of anhydrobiotic organisms during extreme environmental conditions. A key protection feature is their capability to form the hydrogen bond (HB) network in a similar fashion as the one made by water. Since various ions also affect the HB network in completely hydrated systems, it is of a great interest to understand how they impact preservation when incorporated in a disaccharide network. To address this, we employ a combination of experimental and modeling techniques to study behavior of multilamellar 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes freeze-dried with sucrose in presence of NaCl or NaH2PO4·H2O at various concentrations (0...
November 24, 2017: Chemistry and Physics of Lipids
Oumaima Et-Thakafy, Nicolas Delorme, Fanny Guyomarc'h, Christelle Lopez
Sphingomyelin (SM) molecules are major lipid components of plasma membranes that are involved in functional domains. Among natural SMs, that found in milk (milk-SM) exhibits important acyl chain heterogeneities in terms of length and saturation, which could affect the biophysical properties and biological functions of the milk fat globule membrane or of liposome carriers. In this study, the thermotropic and mechanical properties of milk-SM, synthetic C16:0-SM, C24:0-SM and the binary mixtures C16:0-SM/C24:0-SM (50:50% mol) and C24:0-SM/C24:1-SM (95:5% mol) bilayer membranes were investigated using differential scanning calorimetry and atomic force microscopy, respectively...
November 22, 2017: Chemistry and Physics of Lipids
Weria Pezeshkian, Guillaume Chevrot, Himanshu Khandelia
We address unresolved questions of the energetics and mechanism of Lipid Droplet (LD) biogenesis, and of the role of Caveolins in the endoplasmic reticulum (ER) and in mature LDs. LDs are eukaryotic repositories of neutral lipids, which are believed to be synthesised in the ER. We investigate the effects of a curvature-inducing protein, caveolin-1, on the formation and structure of a spontaneously aggregated triolein (TO) lipid lens in a flat lipid bilayer using Molecular Dynamics (MD) simulations. A truncated form of Caveolin-1 (Cav1) localises on the interface between the spontaneously formed TO aggregate and the bulk bilayer, and thins the bilayer at the edge of the aggregate, which may contribute to lowering the energy barrier for pinching off the aggregate from the host bilayer...
November 18, 2017: Chemistry and Physics of Lipids
F Corrales Chahar, S B Díaz, A Ben Altabef, C Gervasi, P E Alvarez
In this paper we study the interactions of two biomolecules (ascorbic acid and Annonacin) with a bilayer lipid membrane. Egg yolk phosphatidylcholine (eggPC) liposomes (in crystalline liquid state) were prepared in solutions of ascorbic acid (AA) at different concentration levels. On the other hand, liposomes were doped with Annonacin (Ann), a mono-tetrahydrofuran acetogenin (ACG), which is an effective citotoxic substance. While AA pharmacologic effect and action mechanisms are widely known, those of Ann's are only very recently being studied...
November 17, 2017: Chemistry and Physics of Lipids
Eduardo Mateos-Diaz, Priscila Sutto-Ortiz, Moulay Sahaka, Deborah Byrne, Hélène Gaussier, Frédéric Carrière
The interaction of pancreatic lipase-related protein 2 (PLRP2) with various micelles containing phospholipids was investigated using pHstat enzyme activity measurements, differential light scattering, size exclusion chromatography (SEC) and transmission IR spectroscopy. Various micelles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and lysophosphatidylcholine were prepared with either bile salts (sodium taurodeoxycholate or glycodeoxycholate) or Triton X-100, which are substrate-dispersing agents commonly used for measuring phospholipase activities...
November 16, 2017: Chemistry and Physics of Lipids
Eduardo Mateos-Diaz, Priscila Sutto-Ortiz, Moulay Sahaka, Jorge A Rodriguez, Frédéric Carrière
Usual methods for the continuous assay of lipolytic enzyme activities are mainly based on the titration of free fatty acids, surface pressure monitoring or spectrophotometry using substrates labeled with specific probes. These approaches only give a partial information on the chemistry of the lipolysis reaction and additional end-point analyses are often required to quantify both residual substrate and lipolysis products. We used transmission infrared (IR) spectroscopy to monitor simultaneously the hydrolysis of phospholipids by guinea pig pancreatic lipase-related protein 2 (GPLRP2) and the release of lipolysis products...
November 11, 2017: Chemistry and Physics of Lipids
Maria Wadsäter, Justas Barauskas, Fredrik Tiberg, Tommy Nylander
The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/glycerol dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A2 (PLA2) that catalysis degradation of the phospholipid component, SPC, and porcine pancreatic triacylglycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO...
November 10, 2017: Chemistry and Physics of Lipids
Kentaro Suzuki, Koichiro Machida, Kazuo Yamaguchi, Tadashi Sugawara
Here, we used centrifugal precipitation to construct a giant vesicle (GV) encapsulating smaller giant vesicles (GV-in-GV) which comprises a photo-resistant outer GV and a photo-pierceable inner GV; the outer GV contained a fluorescent probe (SYBR Green I) in its inner water pool, and the inner GV contained double-stranded DNA (dsDNA) in its inner water pool. The phospholipid membrane of the inner GV was made photo-pierceable by inclusion of ca. 15mol% of a caged phospholipid in its membrane. Immediately after exposure of the GV-in-GVs to UV irradiation, strong fluorescence was detected in the inner water pool of the outer GV, indicating that dsDNA had been released from the inner GV and had complexed with the fluorescent probe...
November 9, 2017: Chemistry and Physics of Lipids
K S Joshy, S Snigdha, George Anne, Kalarikkal Nandakumar, Pothen Laly A, Thomas Sabu
Zidovudine (AZT) is an antiviral drug with moderate solubility in water. It has limited application due to its short half life in vivo and consequent requirement for frequent administrations. To solve this problem, zidovudine loaded polyvinylpyrrolidone (PVP)/stearic acid (SA)-polyethylene glycol (PEG) nanoparticles (PSNPs) were developed.The hybrid nanoparticles were prepared by emulsification-solvent evaporation method. The physico chemical characterizations of the PSNPs was done by dynamic light scattering (DLS), transmission electron microscopy (TEM), and fourier transform infra-red spectroscopy (FT-IR)...
November 9, 2017: Chemistry and Physics of Lipids
Arne Stamm, Allan Svendsen, Jakob Skjold-Jørgensen, Thomas Vissing, Ida Berts, Tommy Nylander
In spite of the importance of the triglyceride aqueous interface for processes like emulsification, surfactant interactions and lipase activity, relatively little is known about this interface compared to that between alkanes and water. Here, the contact between triolein and water was investigated in terms of water inclusion in the oil phase and orientation of the molecules at the interface. Coarse grained models of triglycerides in contact with water were constructed and correlated with experimental results of the changes in thickness and refractive index, obtained using spectroscopic ellipsometry of spin-coated triolein films...
November 9, 2017: Chemistry and Physics of Lipids
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