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Chemistry and Physics of Lipids

Takuo Osawa, Jahangir Md Alam, Nobuo N Noda
Autophagy is an intracellular degradation system conserved among eukaryotes that mediates the degradation of various biomolecules and organelles. During autophagy, a double membrane-bound organelle termed an autophagosome is synthesized de novo and delivers targets from the cytoplasm to the lysosomes for degradation. Autophagosome formation involves complex and dynamic membrane rearrangements, which are regulated by dozens of autophagy-related (Atg) proteins. In this review, we summarize our current knowledge of membrane-binding domains and motifs in Atg proteins and discuss their roles in autophagy...
November 8, 2018: Chemistry and Physics of Lipids
Helya Najafi, Shannon L Servoss
Cell function is tied to the interactions that occur within and across the cell membrane. Therefore, understanding membrane-affiliated interactions is important to many biomedical applications. Advancing the body of knowledge about these interactions will lead to discoveries in biomarker detection and therapeutic targets for disease detection and treatment. Model membrane systems are an effective way to study membrane proteins for such discoveries, allowing for stable protein structure and maintaining native activity...
November 1, 2018: Chemistry and Physics of Lipids
Gourab Prasad Pattnaik, Hirak Chakraborty
Membrane fusion is an integral part of the viral infection. The fusion between an enveloped virus and a host cell is the first step for viral infection. It has been a long-standing effort to develop anti-viral therapies involving inhibitors that block the fusion between virus and host cell. However, these inhibitors are highly specific against a particular virus. Development of generic inhibitors is extremely essential in the current scenario to overcome emerging and re-emerging contagious diseases that cause millions of fatalities every year...
October 29, 2018: Chemistry and Physics of Lipids
A R Verde, M B Sierra, L M Alarcón, V I Pedroni, G A Appignanesi, M A Morini
Docosahexaenoic acid (DHA, 22:6) is a natural active compound that has raised considerable interest due to its several biological effects. In this work, effects of free DHA on the physicochemical properties of dipalmitoylphosphatidylcholine (DPPC) liposomes are investigated in terms of lipid membrane structure, by means of temperature-dependent zeta potential measurements, density studies and molecular dynamics simulations. Experimental results predict, in good agreement with simulations that DHA readily incorporates into DPPC liposomes, localizing at the lipid headgroup region...
October 22, 2018: Chemistry and Physics of Lipids
Marco M Manni, Jesús Sot, Enara Arretxe, Rubén Gil-Redondo, Juan M Falcón-Pérez, David Balgoma, Cristina Alonso, Félix M Goñi, Alicia Alonso
Sphingolipids consist of a sphingoid base N-linked to a fatty acyl chain. Among them, sphingomyelins (SM) are major components of mammalian cells, while ceramide (Cer) plays an important role as a lipid second messenger. We have performed a quantitative lipidomic study of Cer and SM species in different mammalian tissues (adipose tissue, liver, brain and blood serum of human, mice, rat and dog), as well as in cell cultures of mammalian origin (primary hepatocytes, immortalized MDCK cells, mice melanoma b16 cells, and mice primary CD4 + T lymphocytes) using an ultra-high performance liquid chromatography coupled to time-of-flight mass spectrometry (UHPLC-ToF-MS)-based platform...
October 22, 2018: Chemistry and Physics of Lipids
Sivaramakrishna D, Chinapaka Ravindar, Musti J Swamy
N-Acyl tris(hydroxymethyl)aminomethanes (N-acyl tris, NATs) are structural analogs of ceramides, which were reported to induce apoptosis either by elevation of ceramide levels or by activation of pro-apoptotic effectors that are physiological targets of ceramide. In this study, we synthesized and characterized a homologous series of NATs bearing saturated acyl chains (n = 9-18) and investigated their supramolecular organization and thermotropic phase behavior. Transition enthalpies and entropies obtained from differential scanning calorimetric studies showed linear dependence on the chain length in both dry and hydrated states...
October 17, 2018: Chemistry and Physics of Lipids
Yingying Feng, Hu Haimei, Shuanghong Liang, Dan Wang
No abstract text is available yet for this article.
October 8, 2018: Chemistry and Physics of Lipids
Oluwatosin O Ojo, David S Leake
Oxidation of low density lipoprotein (LDL) has been proposed to be involved in the pathogenesis of atherosclerosis. We have previously shown that LDL can be oxidised by iron in lysosomes. As the iron-storage protein ferritin might enter lysosomes by autophagy, we have investigated the ability of ferritin to catalyse LDL oxidation at lysosomal pH. LDL was incubated with ferritin at 37 °C and pH 4.5 and its oxidation monitored spectrophotometrically at 234 nm by the formation of conjugated dienes and by measuring oxidised lipids by HPLC or a tri-iodide assay...
October 1, 2018: Chemistry and Physics of Lipids
Jiadan Hong, Huifang Yang, Dongwen Pang, Luxi Wei, Chunlin Deng
Lipid vesicles are an attractive model membrane experimental platform that is widely used in a biological context. The stability of vesicles can affect their performance and depends on various experimental conditions. How bio-related ions affect vesicle morphology is poorly understood in some cases. Herein, we investigated changes in vesicle morphology influenced by cation in the static and flowing environments. The effects of different mono- and di-valent metal cations on the morphology of lipid vesicles were systematically studied using the various techniques...
September 22, 2018: Chemistry and Physics of Lipids
Grażyna Neunert, Jolanta Tomaszewska-Gras, Przemyslaw Siejak, Zuzanna Pietralik, Maciej Kozak, Krzysztof Polewski
α-Tocopherol oxalate (TO), a tocopherol ester derivative, was investigated for its effect on the structural changes of fully hydrated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes, as a function of concentration and temperature, by applying differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and DPH fluorescence anisotropy methods. The DSC and DPH anisotropy data indicated that TO embedded into DPPC membrane lowered the enthalpy (ΔHm ) and temperature (Tm ) of the main phase transition as well its cooperativity...
November 2018: Chemistry and Physics of Lipids
Thomas Schmitt, Reinhard H H Neubert
This review is summarizing an important part of the state of the art in stratum corneum research. A complete overview on discoveries about the general biophysical and physicochemical properties of the known ceramide species' is provided. The ceramides are one of the three major components of the lipid matrix and mainly govern its properties and structure. They are shown to exhibit very little redundancy, despite the minor differences in their chemical structure. The results are discussed, compared to each other as well as the current base of knowledge...
November 2018: Chemistry and Physics of Lipids
David Beriashvili, Robert Taylor, Braden Kralt, Nooran Abu Mazen, Scott D Taylor, Michael Palmer
Daptomycin is a lipopeptide antibiotic that binds and permeabilizes the cell membranes of Gram-positive bacteria. Membrane permeabilization requires both calcium and phosphatidylglycerol (PG) in the target membrane, and it correlates with the formation of an oligomer that likely comprises eight subunits, which are evenly distributed between the two membrane leaflets. In both bacterial cells and model membranes, changes in the fatty acyl composition of the membrane phospholipids can prevent permeabilization...
November 2018: Chemistry and Physics of Lipids
Shigesaburo Ogawa, Koji Honda, Taro Tsubomura, Kiichiro Totani, Isao Takahashi, Setsuko Hara
The understanding of the basic physicochemical properties of trehalose lipid is indispensable to extending their availability. In this study, the hydrate crystal (Cr), the liquid crystalline (LC) phase and the glassy state formations of 6-O-acyl trehalose fatty acid monoester (TREn) were examined under in a desiccated system. TREn (n = 10, 12, 14, 16) formed monohydrate Cr and showed the hydrate Cr-glassy fluid lamellar LC (Lα) phase transition via dehydration in the heating process. Here, Lα phase for TRE10 and TRE12 was kinetically formed by the dehydration below the glass transition temperature (Tg )...
November 2018: Chemistry and Physics of Lipids
Daniel Canals, Silvia Salamone, Yusuf A Hannun
In the last 30 years, ceramides have been found to mediate a myriad of biological processes. Ceramides have been recognized as bioactive molecules and their metabolizing enzymes are attractive targets in cancer therapy and other diseases. The molecular mechanism of action of cellular ceramides are still not fully established, with insights into roles through modification of lipid rafts, creation of ceramide platforms, ceramide channels, or through regulation of direct protein effectors such as protein phosphatases and kinases...
November 2018: Chemistry and Physics of Lipids
Asma Zaidi, Inger Lise Alsvik, Christer L Øpstad, Daniel Martin, Eduard Rebman, Georg Voss, Hans-Richard Sliwka, Vassilia Partali
The term "fatty acids" is conceptually well defined with regard to fats, whose extent of saturation or unsaturation is precisely indicated in the content description of foodstuff. In contrast, the term "fatty acid" gives no hint of being associated with "soap" (Na and K salts of fatty acids). Fatty acids in edible fats or in cleaning soaps have one thing in common: they are colorless. The prevalence of colorless fats and unadulterated white soaps has ensured that fatty acids are not associated with color...
November 2018: Chemistry and Physics of Lipids
Zainelabdeen H Mohamed, Cosima Rhein, Essa M Saied, Johannes Kornhuber, Christoph Arenz
Förster resonance energy transfer (FRET) probes are unique tools in biology, as they allow for a non-destructive monitoring of a certain state of a biomolecule or of an artificial substrate within living cells in real time. FRET substrates indicate their relative cleavage rate and thus the in situ activity of a given enzyme. In contrast to quenched probes or turn-on probes, one of the two separate signals of the FRET probes can be used as internal reference, which makes ratio-imaging and quantitation of cleavage events independent of cellular delivery possible...
November 2018: Chemistry and Physics of Lipids
Dayane S Alvares, Taisa G Viegas, João Ruggiero Neto
Peptide sequences containing acidic and basic residues could potentially have their net charges modulated by bulk pH with a possible influence on their lytic activity in lipid vesicles. The present study reports on a biophysical investigation of these modulatory effects on the synthetic mastoparan-like peptide L1A (IDGLKAIWKKVADLLKNT-NH2). At pH 10.0 L1A was 6 times more efficient in lysing large anionic (1-palmitoyl-oleoyl-sn-glycero-3-phosphocholine (POPC):1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG)/(8:2)) unilamellar vesicles (LUVs) than at pH 4...
November 2018: Chemistry and Physics of Lipids
Jasmeet Singh, Miroslav Peric
The interactions of the Alzheimer's β-amyloid peptide, Aβ(25-35), with 18:1 (Δ9-Cis) PC 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), L-α-phosphatidylcholine (EPC), 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (DOPG), and L-α-phosphatidylglycerol (EPG) phospholipid vesicles with and without cholesterol (Ch) are studied by the nitroxide spin probe electron paramagnetic resonance (EPR) method. Two nitroxide spin probes, 2,2,6,6-tetramethyl-piperidin-1-oxyl-4-yl hexadecanoate (TP, TEMPO-Palmitate) and 2-Ethyl-2-(15-methoxy-15-oxopentadecyl)-4,4-dimethyl-3-oxazolidinyloxy (16-DSE), are utilized in the study...
November 2018: Chemistry and Physics of Lipids
Fatemeh Haghighi, Vahideh Rabani, Jean-Paul Pais-De-Barros, Siamak Davani
Platelets are major targets for the treatment of thrombo-embolic disorders. Their plasma membrane contains specialized microdomains enriched in sphingomyelins and free cholesterol including membrane receptors. P2Y12 receptors need to be situated in these domains to be able to conduct activation signaling by adenosine diphosphate (ADP). We studied the impact of ticagrelor, a P2Y12 antagonist, and ADP on the composition and distribution of sphingomyelins in detergent-resistant membrane (DRM) of platelet membranes...
November 2018: Chemistry and Physics of Lipids
Rama Prajapati, Stefan Salentinig, Anan Yaghmur
Lyotropic non-lamellar liquid crystalline (LLC) nanoparticles are attractive nanocarriers for drug delivery, particularly for the solubilization of poorly water-soluble drugs. Due to the reported problems of complement activation and cytotoxicity of most investigated Pluronic F127-stabilized cubosomes and hexosomes, there is an interest in introducing safe stabilizers for these LLC nanodispersions. Citrem appears to be the stabilizer of choice for the colloidal stabilization of these LLC nano-self-assemblies owing to its hemocompatiblity and poor activation of the complement system...
November 2018: Chemistry and Physics of Lipids
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