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membran lipids

Hwankyu Lee
Polyelectrolyte bilayers, which consist of poly-l-lysine (PLL) and hyaluronic acid (HA) were simulated with lipid membranes at different temperatures and ion concentrations. Starting with the sequential deposition of PLL and HA above the membrane surface, PLL and HA become completely mixed, leading to the formation of stable bilayers. PLL/HA bilayers are thicker at higher salt concentration because of weakened electrostatic interactions between PLLs and membrane lipids, in agreement with experiments. This salt effect decreases as PLL size increases...
September 23, 2016: Journal of Molecular Graphics & Modelling
Makoto Yoshimoto
Phospholipid vesicle (liposome) offers an aqueous compartment surrounded by lipid bilayer membranes. Various enzyme molecules have been reported to be encapsulated in liposomes. The liposomal enzyme shows peculiar catalytic activity and selectivity to the substrate in the bulk liquid, which are predominantly derived from the substrate permeation resistance through the membrane. We reported that the quaternary structure of bovine liver catalase and alcohol dehydrogenase was stabilized in liposomes through their interaction with lipid membranes...
2017: Methods in Molecular Biology
Florian Graef, Branko Vukosavljevic, Jean-Philippe Michel, Marius Wirth, Oliver Ries, Chiara De Rossi, Maike Windbergs, Véronique Rosilio, Christian Ducho, Sarah Gordon, Claus-Michael Lehr
Gram-negative bacteria possess a unique and complex cell envelope, composed of an inner and outer membrane separated by an intermediate cell wall-containing periplasm. This tripartite structure acts intrinsically as a significant biological barrier, often limiting the permeation of anti-infectives, and so preventing such drugs from reaching their target. Furthermore, identification of the specific permeation-limiting envelope component proves difficult in the case of many anti-infectives, due to the challenges associated with isolation of individual cell envelope structures in bacterial culture...
October 18, 2016: Journal of Controlled Release: Official Journal of the Controlled Release Society
Valentina Longobardi, Angela Salzano, Giuseppe Campanile, Raffaele Marrone, Francesco Palumbo, Milena Vitiello, Gianluigi Zullo, Bianca Gasparrini
The aim of this study was to evaluate the effect of carnitine supplementation of semen extender on fertility parameters of frozen-thawed buffalo sperm. Buffalo semen was cryopreserved in BioXcell containing 0 (control group), 2.5 and 7.5-mM carnitine. After thawing, viability, motility, membrane integrity and capacitation status (assessed by localization of phosphotyrosine-containing proteins and chlortetracycline, chlortetracycline assay) were evaluated. Furthermore, total antioxidant capacity, reactive oxygen species (ROS) and lipid peroxidation levels, as well as adenosine triphosphate (ATP) content and phospholipids concentration were assessed...
September 20, 2016: Theriogenology
R Boni, A Gallo, S Cecchini
Owing to the progressive decline of sperm motility during storage there is a need to find substances capable of enhancing sperm energy metabolism and motility and/or preserving it from oxidative damage. The aim of this study was to evaluate in frozen/thawed bovine spermatozoa the effect of several compounds, such as myo-inositol, pentoxifylline, penicillamine + hypotaurine + epinephrine mixture (PHE), caffeine and coenzyme Q10+ zinc + d-aspartate mixture (CZA), on either kinetic or metabolic parameters. Sperm kinetics was evaluated by Sperm Class Analyser whereas specific fluorochromes were used to evaluated mitochondrial membrane potential (MMP), intracellular pH, intracellular calcium concentration and lipid peroxidation...
October 21, 2016: Andrology
Raquel Marin, Noemí Fabelo, Virginia Martín, Paula Garcia-Esparcia, Isidre Ferrer, David Quinto-Alemany, Mario Díaz
Lipid rafts are highly dynamic membrane microdomains intimately associated with cell signaling. Compelling evidence has demonstrated that alterations in lipid rafts are associated with neurodegenerative diseases such Alzheimer's disease, but at present, whether alterations in lipid raft microdomains occur in other types of dementia such dementia with Lewy bodies (DLB) remains unknown. Our analyses reveal that lipid rafts from DLB exhibit aberrant lipid profiles including low levels of n-3 long-chain polyunsaturated fatty acids (mainly docosahexaenoic acid), plasmalogens and cholesterol, and reduced unsaturation and peroxidability indexes...
September 6, 2016: Neurobiology of Aging
Benoîte Bourdin, Emilie Segura, Marie-Philippe Tétreault, Sylvie Lesage, Lucie Parent
Inherited or de novo mutations in cation-selective channels may lead to sudden cardiac death. Alteration in the plasma membrane trafficking of these multi-spanning transmembrane proteins, with or without change in channel gating, is often postulated to contribute significantly in this process. It has thus become critical to develop a method to quantify the change of the relative cell surface expression of cardiac ion channels on a large scale. Herein, a detailed protocol is provided to determine the relative total and cell surface expression of cardiac L-type calcium channels CaV1...
September 28, 2016: Journal of Visualized Experiments: JoVE
Himanshu Chaudhary, Aditya Iyer, Vinod Subramaniam, Mireille M A E Claessens
Phospholipid vesicles are commonly used to get insight into the mechanism by which oligomers of amyloidogenic proteins damage membranes. Oligomers of the protein α-synuclein (αS) are thought to create pores in phospholipid vesicles containing a high amount of anionic phospholipids but fail to damage vesicle membranes at lower surface charge densities. The current understanding of how αS oligomers damage membranes is thus incomplete. This incomplete understanding may, in part, result from the choice of model membrane systems...
October 21, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Hongwei Yao, Myungwoon Lee, Shu Y Liao, Mei Hong
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 the parainfluenza virus 5 (PIV5) fusion protein F using solid-state NMR...
October 21, 2016: Biochemistry
Mercedes Garcia-Gil, Elisabetta Albi
In the last 20 years it has been widely demonstrated that cell nucleus contains neutral and polar lipids localized in nuclear membranes, nucleoli, nuclear matrix and chromatin. Nuclear lipids may show specific organization forming nuclear lipid microdomains and have both structural and functional roles. Depending on their localization, nuclear lipids play different roles such as the regulation of nuclear membrane and nuclear matrix fluidity but they also can act as platforms for vitamin and hormone function, for active chromatin anchoring, and for the regulation of gene expression, DNA duplication and transcription...
October 20, 2016: Neurochemical Research
Daniela Albanesi, Diego de Mendoza
Phospholipids and fatty acids are not only one of the major components of cell membranes but also important metabolic intermediates in bacteria. Since the fatty acid biosynthetic pathway is essential and energetically expensive, organisms have developed a diversity of homeostatic mechanisms to fine-tune the concentration of lipids at particular levels. FapR is the first global regulator of lipid synthesis discovered in bacteria and is largely conserved in Gram-positive organisms including important human pathogens, such as Staphylococcus aureus, Bacillus anthracis, and Listeria monocytogenes...
2016: Frontiers in Molecular Biosciences
Mario Encinar, Santiago Casado, Alicia Calzado-Martín, P Natale, Álvaro San Paulo, Montserrat Calleja, Marisela Vélez, Francisco Monroy, Iván López-Montero
Erythrocyte membranes have been particularly useful as a model for studies of membrane structure and mechanics. Native erythroid membranes can be electroformed as giant unilamellar vesicles (eGUVs). In the presence of ATP, the erythroid membrane proteins of eGUVs rearrange into protein networks at the microscale. Here, we present a detailed nanomechanical study of individual protein microfilaments forming the protein networks of eGUVs when spread on supporting surfaces. Using Peak Force tapping Atomic Force Microscopy (PF-AFM) in liquid environment we have obtained the mechanical maps of the composite lipid-protein networks supported on solid surface...
October 13, 2016: Colloids and Surfaces. B, Biointerfaces
Zuriñe Antón, Ane Landajuela, Javier H Hervás, L Ruth Montes, Sonia Hernández-Tiedra, Guillermo Velasco, Felix M Goñi, Alicia Alonso
The phospholipid cardiolipin (CL) has been proposed to play a role in selective mitochondrial autophagy, or mitophagy. CL externalization to the outer mitochondrial membrane would act as a signal for the human Atg8 ortholog subfamily, MAP1LC3 (LC3). The latter would mediate both mitochondrial recognition and autophagosome formation, ultimately leading to removal of damaged mitochondria. We have applied quantitative biophysical techniques to the study of CL interaction with various Atg8 human orthologs, namely LC3B, GABARAPL2 and GABARAP...
October 20, 2016: Autophagy
Binod Kumar, Dipanjan Dutta, Jawed Iqbal, Mairaj Ahmed Ansari, Arunava Roy, Leela Chikoti, Gina Pisano, Mohanan Valiya Veettil, Bala Chandran
Kaposi's sarcoma-associated herpesvirus (KSHV) binding to the endothelial cell surface heparan sulfate is followed by sequential interactions with α3β1, αVβ3 and αVβ5 integrins and Ephrin A2 receptor tyrosine kinase (EphA2R). These interactions activate host cell pre-existing FAK, Src, PI3-K and RhoGTPase signaling cascades, c-Cbl mediated ubiquitination of receptors, recruitment of CIB1, p130Cas and Crk adaptor molecules, and membrane bleb formation leading to lipid raft dependent macropinocytosis of KSHV into human microvascular dermal endothelial (HMVEC-d) cells...
October 2016: PLoS Pathogens
Chao-Chen Lin, Hsin-Fang Hsu, Peter Jomo Walla
The fusion of two opposing membranes is essential in biological functions such as fertilization, viral entry, membrane trafficking and synaptic transmission. Before the membrane bilayers are fully connected, at some stage a hemifusion intermediate-when the outer leaflets are merged but not the inner leaflets-is formed. However, the position of hemifusion in the energy landscape and the duration of it vary and have not been fully mapped out. To date, there has not been a way to differentiate lipid mixing of the two leaflets directly in a single experiment...
October 20, 2016: Journal of Physical Chemistry. B
Yadveer Singh Grewal, Muhammad J A Shiddiky, Stephen M Mahler, Gerard A Cangelosi, Matt Trau
Rapid progress in disease biomarker discovery has increased the need for robust detection technologies. In the past several years, the designs of many immunoaffinity reagents have focused on lowering costs, improving specificity while also promoting stability. Antibody fragments (scFvs) have long been displayed on the surface of yeast and phage libraries for selection, however the stable production of such fragments presents challenges that hamper their widespread use in diagnostics. Membrane and cell wall proteins similarly suffer from stability problems when solubilized from their native environment...
October 20, 2016: ACS Applied Materials & Interfaces
Nirod Kumar Sarangi, K G Ayappa, Sandhya S Visweswariah, Jaydeep Kumar Basu
Cell membranes are believed to be highly complex dynamical systems having compositional heterogeneity involving several types of lipids and proteins as the major constituents. This dynamical and compositional heterogeneity is suggested to be critical to the maintenance of active functionality and response to chemical, mechanical, electrical and thermal stresses. However, delineating the various factors responsible for the spatio-temporal response of actual cell membranes to stresses can be quite challenging...
October 20, 2016: Physical Chemistry Chemical Physics: PCCP
Anna P Muir, Flavia L D Nunes, Stanislas F Dubois, Fabrice Pernet
Acclimation and adaptation, which are key to species survival in a changing climate, can be observed in terms of membrane lipid composition. Remodelling membrane lipids, via homeoviscous adaptation (HVA), counteracts membrane dysfunction due to temperature in poikilotherms. In order to assess the potential for acclimation and adaptation in the honeycomb worm, Sabellaria alveolata, a reef-building polychaete that supports high biodiversity, we carried out common-garden experiments using individuals from along its latitudinal range...
October 20, 2016: Scientific Reports
Asanga Bandara, Afra Panahi, George A Pantelopulos, John E Straub
For 40 years, the existence and possible functional importance of cholesterol dimer formation has been discussed. Due to challenges associated with structural studies of membrane lipids, there has as yet been no direct experimental verification of the existence and relevance of the cholesterol dimer. Building on recent advances in lipid force fields for molecular simulation, in this work the structure and stability of the cholesterol dimer is characterized in POPC bilayers in absence and presence of sphingomyelin...
October 20, 2016: Journal of Computational Chemistry
Laureano M Alarcón, M de Los Angeles Frías, Marcela A Morini, M Belén Sierra, Gustavo A Appignanesi, E Anibal Disalvo
We employ molecular dynamics simulations to study the hydration properties of Dipalmitoylphosphatidylcholine (DPPC) bilayers, both in the gel and the liquid crystalline states. We show that while the tight hydration centers (PO and CO moieties) are significantly hydrated in both phases, the gel-fluid transition involves significant changes at the second hydration shell, particularly at the buried region between the hydrocarbon tails. Thus, while almost no buried water population exists in the gel state below the carbonyls, this hydrophobic region becomes partially water accesible in the liquid crystalline state...
October 2016: European Physical Journal. E, Soft Matter
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