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Carmical, Jennifer, and Stacy D. Brown. "The Impact of Phospholipids and Phospholipid Removal on Bioanalytical Method Performance." Digital Commons @ East Tennessee State University, 2016. https://doi.org/10.1002/bmc.3686.
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Phospholipids (PLs) are a component of cell membranes, biological fluids and tissues. These compounds are problematic for the bioanalytical chemist, especially when PLs are not the analytes of interest. PL interference with bioanalysis highly impacts reverse-phase chromatographic methods coupled with mass spectrometric detection. Phospholipids are strongly retained on hydrophobic columns, and can cause significant ionization suppression in the mass spectrometer, as they out-compete analyte molecules for ionization. Strategies for improving analyte detection in the presence of PLs are reviewed, including in-analysis modifications and sample preparation strategies. Removal of interfering PLs prior to analysis seems to be most effective at moderating the matrix effects from these endogenous cellular components, and has the potential to simplify chromatography and improve column lifetime. Products targeted at PL removal for sample pre-treatment, as well as products that combine multiple modes of sample preparation (i.e. Hybrid SPE), show significant promise in mediating the effect on PL interference in bioanalysis.
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Zschörnig, Kristin. "Massenspektrometrische Untersuchungen an Spermien-Phospholipidmembranen." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-154791.
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Fettleibigkeit und Adipositas haben in den letzten Jahren weltweit drastisch zugenommen. Die Fettleibigkeit geht nicht nur mit einer verringerten Lebensqualität einher, sondern ist auch mit verschiedenen Folgeerkrankungen, wie kardiovaskulären Erkrankungen (z.B. Arteriosklerose) und metabolische Erkrankungen (z.B. Diabetes) assoziiert. Vorliegende Studien belegen einen Zusammenhang zwischen Diabetes und männlicher Infertilität. In der vorliegenden Arbeit wurden daher die Spermienmembran wie auch das Seminalplasma (SP) mittels matrix-assisted laser desorption and ionisation time-of-flight Massenspektrometrie (MALDI-TOF MS) analysiert, um mögliche Lipid-Biomarker für die Fertilität bzw. Infertilität zu finden. Dafür wurde zunächst die MALDI-TOF MS Methode mit relevanten Standardlipiden optimiert. Anschließend konnte sowohl das Phospholipidmuster des SP mit dem Spermien verglichen werden als auch die Spermienlipide von normalgewichtigen und fettleibigen Probanden. Durch diese Analyse konnte das Phosphatidylcholin/Lysophosphatidylcholin (PC/LPC)-Verhältnis, aber auch ein stark erhöhter Sphingomyelin (SM)-Anteil bei den fettleibigen Probanden als Qualitätsmarker gefunden werden. Des Weiteren wurden im Rahmen dieser Arbeit murine Spermien aus dem Caput und dem Cauda der Epididymis mittels MALDI-TOF MS analysiert und das Phospholipidmuster miteinander verglichen. Es konnte damit gezeigt werden, dass die murinen Spermien einen wesentlich höheren Anteil an Stearinsäureresten aufweisen, die humanen Spermien hingegen vor allem durch Palmitinsäurereste charakterisiert sind. In den Spermienmembranen aus dem Cauda und dem Caput gab es wesentliche Unterschiede im Phospholipidmuster. Spermienmembranen aus dem Caput besitzen einen hohen Anteil an PC und Phosphatidylethanolamin (PE). Die Spermienmembranen aus dem Cauda hingegen enthalten mehr SM, und auch einen höheren Anteil an LPCs und Formyl-LPC. Diese Arbeit konnte somit zeigen, dass die Reifungsprozesse in der Epididymis auch die Phospholipid-Zusammensetzung betreffen.
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Pham, Quoc Dat. "Effects of Oxidized Phospholipids and Heavy Water on the Structure of Phospholipid Bilayer Membranes." Thesis, Umeå universitet, Kemiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-57935.
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Murphy, Elizabeth J. "'3'1p NMR studies of phospholipids and phospholipid metabolism and in vivo and in vitro." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315707.
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Meca, Julien. "Etude de l’interaction entre un module de polarité Rho GTPase et l’environnement membranaire chez Saccharomyces cerevisiae." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0204.
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La polarité cellulaire, organisation asymétrique du matériel cellulaire dans l'espace et le temps, est fréquemment observée en biologie. Elle est nécessaire pour de nombreux mécanismes cellulaires essentiels allant de la division cellulaire et la migration au développement et la croissance polarisée. Comprendre comment la cellule génère et maintient cette polarité est crucial, les défauts de polarité étant liés à des maladies graves comme le cancer ou les maladies neurodégénératives. Chez la levure Saccharomyces cerevisiae, la polarité cellulaire est établie lorsque le module de la Rho GTPase Cdc42, qui comprend le facteur d'échange de nucléotide guanine (GEF) Cdc24 et la protéine scaffold Bem1, localise à un unique site à la membrane plasmique pour activer Cdc42 et ainsi, établir un axe de polarité utilisé pour la croissance et la division cellulaire. Les mécanismes responsables de l'activation de Cdc42 à un site unique au cortex pendant l'établissement de la polarité sont essentiels mais largement inconnus. En utilisant des expériences complémentaires d'imagerie in vivo et des expériences in vitro, je mis en évidence que le ciblage avide du module de Cdc42 à la membrane plasmique implique des interactions multivalentes entre des lipides anioniques et le module de Cdc42. En détail, j'ai démontré que la combinaison de plusieurs phospholipides anioniques, comprenant PS, PI4P et PI(4,5)P2, est nécessaire à la localisation de Bem1 et Cdc24 in vivo. J'ai identifié des groupements cationiques interagissant avec des lipides (CLICs) dans l'extrémité N-terminale de Bem1 qui étaient nécessaires et suffisants pour interagir avec des phospholipides anioniques. Réduire l’interaction de Bem1 avec les lipides en mutant la séquence CLICs a fortement diminué la localisation de Bem1 au niveau du cortex ainsi que la signalisation de Cdc42. En plus des CLICs de Bem1, le domaine PX de Bem1 et le domaine PH de Cdc24 augmentent davantage l'avidité du module GTPase pour les lipides anioniques et la combinaison des trois domaines est essentielle pour l'établissement de la polarité cellulaire. Ces résultats définissent pour la première fois le mécanisme de ciblage avide des activateurs de Cdc42 à la membrane plasmique pendant l'établissement de l'axe de polaritéCell polarity, the asymmetric organization of cell material in space and time, is frequently observed in biology. It is required for numerous essential cellular processes ranging from cell division and migration to development and polarized growth. Addressing how cells generate and maintain polarity is crucial, since defects in polarity are linked to severe diseases including cancer and neurodegeneration. In the budding yeast Saccharomyces cerevisiae, cell polarity is established when the Cdc42 Rho GTPase module, which includes the Guanine nucleotide Exchange Factor (GEF) Cdc24 and the scaffold protein Bem1, accumulate at a unique site on the plasma membrane to activate Cdc42 and establish the polarity axis used for cell growth and division. The mechanisms responsible for the site-specific activation of Cdc42 at the cortex during polarity establishment are essential but are largely unknown. Using complementary in vivo imaging and in vitro experiments, I found that the avid targeting of the Cdc42 GTPase module to the plasma membrane involves multivalent anionic lipid-Cdc42 module interactions. I found that a combination of anionic phospholipids, including PS, PI4P and PI(4,5)P2, are necessary for Bem1 and Cdc24 localization in vivo. I identified Cationic-enriched Lipid Interacting Clusters (CLICs) in the N-terminus of Bem1 that were necessary and sufficient for anionic phospholipid interactions. Reducing Bem1 lipid binding by mutating the CLICs strongly diminished the localization of Bem1 at the cortex and Cdc42 signaling. In addition to the Bem1 CLICs, the Bem1 PX domain and the Cdc24 PH domain increased the avidity of the GTPase module for anionic lipids, and a combination of all three domains was essential for the establishment of cell polarity. The results of my thesis define a mechanism of avid targeting of Cdc42 activators to the cortex during polarity axis establishment
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Berggren, Anders. "LCA of Egg Phospholipids." Thesis, KTH, Industriell ekologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134201.
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Egg phospholipids are a group of fats or lipids in the egg yolk, commonly used as emulsifiers in the chemical industry to facilitate the dissolving of substances. The pharmaceutical company Fresenius-Kabi manufactures this product and seeks a better understanding of the product’s major environmental impacts in order to comply with the ISO 14001 requirements, communicate its environmental performance and choose raw materials that result in lower environmental impacts. The aim of this study is to quantify and identify environmental impacts that occur in the life cycle of Fresenius-Kabi’s egg phospholipids product, and to suggest improvements on how the impacts could be reduced. The aim has been reached by following the life cycle assessment methodology. The life cycle consists of egg, egg yolk powder and egg phospholipids production. The major inputs to the life cycle include fertilizers, pesticides, hen feed, fuel oil and solvents. The major outputs are hen manure, egg residues, air and water emissions. The results show that the greatest impacts are generated in the production of hen feed, solvent feedstocks, the hen manure handing and the final egg phospholipids production. The most severe environmental impacts are found in the human toxicity and eutrophication impact categories. Pesticide and fertilizers usage in the cultivation of hen feed and solvent feedstocks generate phosphorus, manganese and arsenic emissions, which are emission substance sources in the human toxicity impact category. In addition, nitrate and phosphate emissions from fertilizer and hen manure affect the eutrophication. The emissions of NMVOC and carbon dioxide to air, as well as phosphorus to waste water, are the major environmental concerns in the final egg phospholipids manufacturing. Other impact categories such as climate change, photochemical oxidant formation, terrestrial acidification and fossil depletion have lower global impact. Five scenarios have been conducted in order to validate the results, and to provide Fresenius-Kabi with improvements. Lowering the production and intake of hen feed per kilogram eggs with six percent decrease the environmental impacts by 2 to 6 percent. Changing the ethanol feedstock to cellulose-based feedstocks clearly diminishes the toxicity related emissions due to lower fertilizer and pesticide usage. To replace other fat and protein sources with the egg residue byproduct that is yielded within the life cycle is the best treatment method of the egg’s non-phospholipids content. No specific improvements to the treatment method of the hen manure have been found. The fifth scenario includes a sensitivity analysis on the egg yolk powder allocation factor. To increase it from 11 to 25 percent does not give any significant effect on the final results, since this life cycle phase already has very low environmental impact. Actions that will have a significant effect on the egg phospholipids’ total environmental impact are optimize fertilizer and pesticide usage at hen feed and ethanol feedstock cultivations, lower ammonia and phosphate emissions from the hen manure management, and finally, reduced solvent, carbon dioxide, phosphorus and phosphate emissions from the final egg phospholipids manufacturing. Fresenius-Kabi is recommended to further look into these emission sources in order to decrease the egg phospholipids’ environmental impact.Äggfosfolipider är ett fett eller lipider i äggulan som används som emulgator i kemiindustrin för att förenkla andra medels sammanlösning. Farmasiföretaget Fresenius-Kabi tillverkar den här produkten och söker bättre förståelse för de största miljöproblemen med produktionen av produkten i syfte att uppfylla krav inom ISO 14001, kommunicera sitt miljöarbete, och att välja råmaterial med låg miljöpåverkan. Målet med den här studien är att kvantifiera och identifiera de största miljöproblemen i ett livscykelperspektiv med produktionen av äggfosfolipid. Målet har uppnåtts genom att följa standardmetoden för livscykelanalyser. Livscykeln består av ägg-, äggule och äggfosfolipid produktion. Den mest signifikanta tillförseln av produkter är gödsel, pesticider, hönsavföring, eldningsolja och lösningsmedel. De mest signifikanta produkter som lämnar livscykeln är hönsgödsel, ägg rester, luft och vatten emissioner. Resultaten visar att de mest betydelsefulla miljöproblemen uppstår i äggfosfolipidens livscykel äggproduktionen av hönsfoder och råvaror för etanolproduktion, hanteringen av hönsgödsel och vid den slutgiltiga äggfosfolipid tillverkningen. De mest betydande miljöpåverkanskategorierna är utsläpp av för människan toxiska ämnen och övergödning. Användandet av pesticider och gödsel vid produktion av råvaror till hönsfoder och etanol ger utsläpp av fosfor, mangan och arsenik, vilka är emissionskällor i den här kategorin. Emissioner av nitrat och fosfat från gödsel användning och hantering av hönsavföring är två emissionskällor till övergödningen. Miljöproblem som uppstår i den slutgiltiga äggfosfolipid produktionen är utsläpp av flyktiga kolväten vilka inte inkluderar metan, koldioxid och fosfor i avfallsvattnet. Andra påverkanskatergorier som till exempel klimatförändringarna, försurning och uttag av fossila bränslen har lägra global miljöpåverkan. Fem scenarioer har genomförts för att ge resultaten högre trovärdighet. Att minska produktion och intag av hönsfoder per kilogram ägg med sex procent minskar miljöpåverkan med 2 till 6 procent. Att byta råmaterial vid etanol produktionen till cellulosabaserade material minskar markant utsläppen av toxiska ämnen på grund av mindre användning av pesticider och gödsel. Att ersätta fett och protein källor med äggrester som uppstår i äggfosfolipidproduktionen ger mest nytta i ett miljöperspektiv. Ingen klar bästa behandlingsmetod för hönsavföringen har hittats. Femte scenariot inkluderar en känslighetsanalys på hur miljöpåverkan från äggulepulvret allokeras från övriga äggprodukter. Att öka allokeringsfaktor från 11 procent till 25 procent får ingen nämnvärd effekt på de totala resultaten, eftersom den livscykelfasen där äggulepulvret produceras redan har låg miljöpåverkan. Åtgärder som får störst påverkan på äggfosfolipidens totala miljöpåverkan är att optimera användandet av gödsel och pesticider vid fodertillverkningen och råvaruproduktion av etanol, minska utsläpp av ammonium och fosfater från hönsgödselavföring och gödselanvändning i samband med fodertillverkningen och råvaruproduktion av etanol samt lägre utsläpp av lösningsmedel, koldioxid, fosfor och fosfat från den slutgiltiga äggfosfolipidtillverkningen. Fresenius-Kabi rekomenderas att undersöka de här emissionskällorna för att minska miljöpåverkan från produktion av äggfosfolipid.
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Maheshwari, Sweta. "Caractérisation biochimique et cellulaire des enzymes clés du métabolisme des phospholipides chez Plasmodium falciparum." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20004.
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Le développement du parasite Plasmodium falciparum, responsable du paludisme, nécessite la synthèse de phospholipides et plus particulièrement de phosphatidylcholine (PC) et phosphaditylethanolamine (PE) qui représentent environ 85% de la totalité des phospholidipes du parasite. Leur synthèse s'effectue principalement par les voies métaboliques de novo, voies de Kennedy, en trois étapes enzymatiques. Les enzymes CTP: phosphoethanolamine cytidylyltransferase (ECT) et CTP: phosphocholine cytidylyltransferase (CCT) catalysent les étapes limitantes des deux voies de biosynthèse de la PE et de la PC, respectivement. Ces deux enzymes sont essentielles à la survie du parasite murin, P. berghei et représentent ainsi des cibles thérapeutiques potentielles. La PfCCT est constituée de deux domaines cytidylyltranférases (CT) répétés alors que l'enzyme homologue chez l'homme est composée d'un seul domaine. En revanche, pour la ECT, la présence de deux domaines CT est retrouvée chez toutes les espèces mais les analyses de séquences et de structures ont montré que des résidus importants du site catalytique liant le substrat n'étaient pas conservés dans le domaine CT C-terminal de la PfECT. Ce travail a eu pour but de déterminer les propriétés enzymatiques et les caractéristiques cellulaires de la PfECT et de la PfCCT. Les paramètres cinétiques de ces enzymes ont été quantifiés in vitro à l'aide protéines recombinantes ainsi que sur les enzymes endogènes à l'aide d'extraits parasitaires. Grâce à l'utilisation de protéines recombinantes ponctuellement mutées, nous avons montré que seul le domaine CT N-terminal de la PfECT est catalytiquement actif. Chez P. falciparum, la PfECT et la PfCCT sont exprimées tout au long du cycle intra-érythrocytaire du parasite. La PfECT est présente dans la fraction soluble du parasite alors que la PfCCT apparait aussi bien dans la fraction soluble qu'insoluble. Des expériences d'immunofluorescence ont montré que la PfECT est cytosolique. L'ensemble des résultats présentés apportent un éclairage important sur les fonctions et les propriétés de ces deux cibles potentielles et constituent les premières étapes indispensables à l'élaboration d'une approche thérapeutiquePhospholipids are essential for the growth and development of Plasmodium falciparum malaria parasite. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are its major structural phospholipids. This study focused on CTP: phosphoethanolamine cytidylyltransferase (ECT) and CTP: phosphocholine cytidylyltransferase (CCT) that catalyzes the rate-limiting steps of the de novo Kennedy pathways for PE and PC biosynthesis respectively. Both ECT and CCT are essential in the rodent malaria parasite P. berghei and constitute potential chemotherapeutic targets to fight against malaria. PfCCT consists of two very similar cytidylyltransferase (CT) domains whereas the human enzyme consists of only one CT domain. The presence of two CT domains in ECT seems to be widespread in all the organisms. Sequence and structural analysis showed that the C-terminal CT domain of ECT lacks key residues in the substrate binding motif. This study aimed at unravelling the enzymatic properties and cellular characteristics of PfECT and PfCCT enzymes. In addition, these studies addressed the key question if C-terminal CT domain of PfECT is catalytically active. Kinetic parameters of the enzymes were evaluated in vitro on native proteins as well as on recombinant proteins, the latter being produced in bacterial system. Cellular characterisation studies using polyclonal antisera showed that PfECT and PfCCT are expressed throughout the intra-erythrocytic life cycle of the parasite. PfECT is found mainly in soluble form in the parasite while PfCCT is present in soluble as well as insoluble forms in the parasite. Furthermore, immunofluorescence studies for PfECT revealed that it is mainly cytosolic. To assess the contribution of each CT domain to overall PfECT enzyme activity, recombinant PfECT mutants were generated by site-directed mutagenesis. Kinetic studies on these mutants indicated that the N-terminal CT domain was the only active domain of PfECT. Collectively, these results bring new insights into the kinetic and cellular properties of the enzymes and will pave the way in developing a future pharmacological approach
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Stewart, Laura. "Physical studies of diphytanylglycerol phospholipids." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5405.
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Cuccia, Louis A. "Biophysical properties of dimeric phospholipids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0023/NQ29914.pdf.
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Mohan, Vijitha. "SELECTIVE ESTER CLEAVAGE IN PHOSPHOLIPIDS." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07112008-141938/.
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Selective ester bond cleavage using lithium and zinc halides was attempted in a select group of phospholipids, namely phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS). Several reaction parameters including catalyst (lithium chloride, lithium bromide, lithium iodide, zinc chloride, zinc bromide and zinc iodide), reaction temperature (21, 30, 50 and 60 oC), and reaction time (2 and 4 hours) were varied and the effects on cleavage studied. Reacted phospholipid samples were characterized by attenuated total reflectance (ATR) and transmission FTIR spectroscopy. The FTIR spectra of pure (unreacted) and reacted PC, PE and PE were analyzed qualitatively and quantitatively (Peak Height Ratio). The appearance of asymmetric carboxylate anion stretch (1577 cm-1) and symmetric phosphonyl dianion stretch (1006 cm-1) in the reacted phospholipid spectra reveals cleavage of ester bonds in carbonyl and phosphonyl. Reaction temperature and time did not significantly influence the cleavage results over the temperature and time range tested.
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Cuccia, Louis A. "Biophysical properties of dimeric phospholipids." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42007.
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A series of unusual bipolar and bis-phospholipids (dimeric phospholipids) have been studied. The structure, conformation, morphology and biophysical properties of the resulting phospholipid aggregates were investigated.Deuterium magnetic resonance spectroscopy ($ sp2$H NMR) was used to study and characterize the conformation and acyl chain order in oriented bipolar lipid membranes. The $ sp2$H-NMR studies indicated a large and constant value for the order parameter (S$ rm sb{mol})$ for all positions along the bipolar lipid diacyl chain for mechanically oriented, magnetically oriented and unoriented samples. This indicates that the great majority ($>$90%) of the bipolar lipid exists in a highly ordered spanning conformation.
Dimeric phospholipid aggregate morphologies were studied using $ sp{31}$P NMR, small angle X-ray scattering, electron microscopy, differential scanning calorimetry, and the Langmuir film balance technique in order to study the relationship between lipid structure and aggregate morphology. Dimeric phospholipids favour a lamellar morphology. A number of lipid structure-dependent features have been observed including tri-lamellar structures, extended ripple phases and hexagonal phases.
Dimeric and non-hydrolyzable phospholipids were used to study the phenomenon of interfacial activation of extracellular phospholipase A$ sb2$ (EC. 3.1.1.4) (PLA$ sb2)$ in relation to lipid phase, substrate conformation and mobility. Kinetic results and product analyses are consistent with a situation where the spanning conformer of bipolar phospholipids is resistant to PLA$ sb2$-catalyzed hydrolysis but the hairpin conformer is readily hydrolyzed. Finally, an analysis of interfacial kinetics in non-hydrolyzable matrices indicated varying degrees of interfacial inhibition and hydrolysis product activation. This has not been explicitly recognized before and affects the choice of assay conditions for PLA$ sb2.$
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Tan, Lee Aun. "Immune system interactions with phospholipids." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404272.
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Mackenzie, Andrew Neil. "The synthesis of novel phospholipids." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261435.
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Lee, Youn-Sik. "Supramolecular assemblies of polymerizable phospholipids." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185929.
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Novel polymerizable ether lipids, 1,2-O-bis[10-(2',4'-hexadienoyloxy)decyl]-rac, 1,2-O-bis(10,12-tricosadiynyl)-rac, and (S)-2,3-O-bis(10,12-tricosadiynyl)-sn-glycero-1-phosphocholine (PC), were successfully synthesized. Differential scanning calorimetry (DSC) showed that the gel to liquid crystalline phase transition of the ether lipid bilayers occurs at 11.4, 27.6, and 30.0°C (T(m)), respectively. The T(m) of the saturated analogs of the sorbyl ether and ester lipids, which were synthesized for the study of lipid phase behavior, were -15.4 and -7.5°C, respectively. The sorbyl and diacetylenic ether lipids in bilayers were readily polymerized with 254 nm light. The stability of sorbyl either lipid vesicles toward a detergent, Triton X-100, was somewhat enhanced by photopolymerization. The optically active diacetylenic ether lipid formed microtubules and helices which were observed by transmission electron and optical microscopy. Polymerizable ester lipids, 1-palmitoyl-2-(2-methylene)palmitoyl, 1,2-bis(2-methylenepalmitoyl), and 1-oleoyl-2-(2-methylene)palmitoyl PC were synthesized. The T(m) of these lipids were estimated to be 33.6, 25.3, and ∼-10°C, respectively, via DSC and X-ray diffraction. Thermal reaction of the mono-substituted lipid suspensions with a water-soluble initiator, azobis(2-amidinopropane) dihydrochloride (AAPD), yielded oligomers which were soluble in organic solvents. However, reaction of the bis-substituted ester lipid in bilayers produced cross-linked polymers which are not soluble in organic solvents. The ceiling temperature for the radical polymerization of these lipid systems appears to be near 70°C since the polymerization conversion at 60°C was greater than at 70°C. Finally, a polymerizable ester lipid, 1-oleoyl-2-(2-methylene)palmitoyl-sn-glycerol-3-phosphoethanolamine (PE) was synthesized. According to DSC and X-ray diffraction, this hydrated PE suspension undergoes the transition from the lamellar liquid crystalline to the nonlamellar inverted hexagonal (H(II)) phase at 45-50°C. This compound (T(m) = 11.6°C) is a promising candidate for future studies of the stabilization of the H(II) phase.
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Swiecicki, Jean-Marie. "Étude des mécanismes d'internalisation des peptides pénétrants." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066474.
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Les peptides pénétrants (CPP) se caractérisent par deux propriétés : ils pénètrent dans l'espace intracellulaire et favorisent l'internalisation de cargaisons moléculaires auxquelles ils sont associés. Si les CPP sont très utilisés comme vecteurs en recherche fondamentale, la méconnaissance des mécanismes de pénétration et de leurs distributions intracellulaires limite leur utilisation thérapeutique. Il est admis que les CPP et leurs cargaisons sont internalisés par transport actif (endocytose) et par transport passif (translocation directe). J'ai étudié la translocation directe à l'échelle moléculaire en utilisant des membranes modèles. Les CPP usuels sont internalisés et permettent l'accumulation de cargaisons dans des vésicules unilamellaires. J'ai alors démontré que la translocation directe se déroule via la formation de complexes neutres et hydrophobes CPP-phospholipides.La pénétration intracellulaire des CPP est le plus souvent étudiée par microscopie confocale. J'ai démontré que des fortes concentrations locales de CPP induit une auto-inhibition de leur fluorophore. Cet artefact a conduit à des erreurs d'interprétation dans la littérature quant à la localisation des CPP. Un protocole permettant de révéler la fluorescence éteinte a été proposé et conduit à réévaluer la localisation subcellulaire des CPP ainsi que l'importance relative des mécanismes d'internalisation.Ces résultats ont permis de développer rationnellement de nouveaux vecteurs pénétrants : les oligoarginines acylées par des chaînes grasses dont des insaturations sont de stéréochimie cis. Leur internalisation passive particulièrement importante conduit à la libération de la cargaison dans le cytosolCell penetrating peptides (CPPs) are short cationic sequences capable of shuttling bioactive cargoes into eukaryotic cells. If CPPs are common delivery tools in basic research, their therapeutic use is currently limited because their internalization mechanisms and intracellular distributions remain to be elucidated. In living cells there is evidence for both endocytosis of the CPPs and for “direct translocation”, an energy-independent uptake pathway. I analyzed the direct translocation phenomenon at the molecular level with model membranes. CPPs are internalized into large unilamellar vesicles and trigger the internalization of various cargoes. I then demonstrated that direct translocation occurs through membranes via the formation of a neutral and hydrophobic CPP-anionic phospholipids complex. CPPs internalization is mostly analyzed by confocal microscopy. I demonstrated that fluorescence self-quenching occurs if fluorescently labeled CPPs are locally too concentrated. This severe artifact led to misinterpretation of the subcellular distribution of CPPs. I developed a reliable procedure to avoid this artifact and ranked subcellular regions of living cells depending on their CPP concentration. As a result, I was able to rationalize the subcellular distribution of CPPs and to deduce their penetration mechanisms. The studies that I performed provided valuable information that I used to design a new family of delivery vectors: minimalist oligoarginines peptides acylated by unsaturated fatty acids (cis unsaturations). The direct translocation of these lipopeptides is particularly important yielding to an efficient delivery of a cargo inside the cytosol of living cells
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Mozuraityte, Revilija. "Oxidation of marine phospholipids in liposomes." Doctoral thesis, Norwegian University of Science and Technology, Department of Biotechnology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2008.
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Marine phospholipids contain a high amount of n-3 polyunsaturated fatty acids (PUFAs), which have documented beneficial effect on human health. Due to this, marine phospholipids have a high potential for use in products for human consumption. However, due to the high amount of n-3 PUFAs, marine phospholipids are very susceptible to lipid oxidation, which cause loss of sensory and nutritional value in foods, some oxidation compounds are even toxic. A successful incorporation of marine phospholipids in processed foods would most probably be in the form of lipid dispersions, where some common constituents such as iron would be present. Iron, which is a very important mineral from a nutritional point of view, is also a very strong prooxidant. Studies of oxidation in oil/water systems catalysed by iron would provide valuable information on oxidation kinetics.
This thesis summarises the work done on oxidation of marine phospholipids in liposomes. Measurement of dissolved oxygen uptake was chosen as the main method to study lipid oxidation. This fast and simple method enabled screening of the influence of different conditions on oxidation.
The mechanism for iron catalyzed oxidation in liposomes is discussed. When Fe2+ was added to liposomes, an initial drop in dissolved oxygen followed by a slower linear oxygen uptake, was observed. Addition of Fe3+ induced only the linear oxygen uptake. The initial fast drop in dissolved oxygen was due to breakdown of preexisting lipid peroxides by Fe2+. In this reaction alkoxy radicals were formed and Fe2+ was oxidised to Fe3+. Fe3+ formed was further reduced by peroxides to Fe2+ at a slow rate (compared to Fe2+ oxidation rate). When equilibrium between Fe2+ and Fe3+ was achieved, the linear oxygen uptake was observed and Fe3+ became the rate limiting factor in the circulation between Fe3+ and Fe2+. Both alkoxy and peroxy radicals are presumably formed by breakdown of peroxides by Fe2+ and Fe3+. These radicals react with fatty acids giving a lipid radical reacting with oxygen.
The rate of slower linear oxygen consumption followed Arrhenius kinetics and the variation in activation energy found (60 – 87 kJ/moles*K). The rate of slower linear oxygen uptake in liposomes was proportional to the concentration of iron and the lipid concentration in the assay mixture. The oxygen consumption rate was dependent on pH with a maximum observed between pH 4 and 5. The pH effect was explained by the iron availability and Zeta potential changes at different pH. Different salts had different influence on the linear oxygen uptake in liposomes. Cations (Na+, K+, Ca+, Mg+) did not influence the rate of oxidation in the tested range (Ionic strength (I) 0 - 0.14 M). Among the tested anions: sulphates and nitrates did not change oxygen uptake rate significantly, but chlorides (KCl, NaCl, CaCl2) reduced the oxidation rate down to approximately 45 % and dihydrogen phosphate down to 14 %, when I=0.14M. The effect of Cl- and H2PO4 - was additive. When the liposomes contained different concentrations of chlorides, a linear relationship between oxygen uptake rate and Zeta potential was observed. When phosphate was added, the oxygen uptake rate was not related to the changes in Zeta potential.
The influence of pH, temperature, concentration of NaCl, phospholipids and Fe2+ on slower linear rate were described by mathematical equations. The modelled data based on the described equations fitted within 10% standard deviation with observed values.
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Watts, Emma Elizabeth. "Phosphorus-31 NMR of sediment phospholipids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0008/MQ42111.pdf.
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Arthur, John Simon Campbell. "Regulation of m-calpain by phospholipids." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240569.
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Rogerson, Madeleine. "Interactions of phospholipids with fatty acids." Thesis, University of East Anglia, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398493.
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Crosby, John. "Interactions between prostaglandins, phospholipids and spermatozoa." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/18806.
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Dunjić, Branko S. "Gastric mucosal protection an experimental study on the role of endogenous and exogenous phospholipids /." Lund : Dept. of Surgery, Lund University, 1993. http://catalog.hathitrust.org/api/volumes/oclc/39798502.html.
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Rajagopal, Badri S. "Interactions of mitochondrial cytochrome c with phospholipids." Thesis, University of Essex, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589541.
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Mitochondrial cytochrome c (cyt c) associates with the phospholipid cardiolipin (Cl) through a combination of electrostatic and hydrophobic interactions. The latter occurs by insertion of an acyl chain into cyt c, resulting in the dissociation of the axial Met-80 haem-iron ligand resulting in a five coordinate cyt c/Cl complex that exhibits peroxidatic properties leading to peroxidation of Cl and dissociation of the complex. These events are considered to be pre-apoptotic and culminate with release of cyt c from the mitochondria into the cytoplasm. Two distinct surface regions on cyt c have been suggested to mediate Cl acyl chain insertion and Chapters 2 and 3 of this thesis report the results of probing one of these regions by constructing a series of alanine mutants in yeast iso-l-cyt c aimed at disrupting a surface cleft formed between residues 67-71 and 82-85. The physicochemical properties, peroxidase activity, Cl binding, and kinetics of carbon monoxide (CO) binding to the ferrous cyt c/Cl complex have been assessed for each individual mutant. The findings reveal that the majority of mutants are capable of binding Cl in the same apparent stoichiometry as the wild-type protein. Mutation of the species conserved Arg-91 residue, that anchors the cleft, results in the greatest changes to physicochemical properties of the protein leading to a change in the Cl binding ratio required to effect structural changes and to the ligand-exchange properties of the ferrous cyt c/CL complex. The second part of this thesis, Chapters 4 and 5, switches focus to human cyt c. A recently discovered natural mutant of human cyt c - G41S, was found to have enhanced apoptotic activity in megakaryocytes leading to thrombocytopenia. An expression construct for WT human cyt c was prepared enabling the G41S mutation to be made and studied. Peroxidase activity in the presence and absence of three phospholipids (TOCl, DOPS and DOPG) was studied and revealed enhanced activity for the G41S mutant in the presence of TOCL. To correlate a mechanism of peroxidase activity in the human cyt c/lipid complex an extensive EPR study was carried out which identifies the spin state changes of haem-iron upon peroxidation of cyt c/lipid complexes. Furthermore, the EPR study identifies that a Tvr radical is formed during peroxide turnover by the cyt c/lipid complex. Identification of which of the five Tyr residues in human cyt c the radical resides has been aided by the crystal structure of human cyt c with Tyr- 46 or Tyr-48 being identified. Further work is required to confirm which of the two Tyr residues act as the radical site.
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Lexelius, Rebecka. "Formation of Monolayered Phospholipids using Molecular Dynamics." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-356370.
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The very fundamental properties of biological membranes can be understood by studying their formation. This sets a good foundation for research related to how the membranes interact with organic molecules and ions; something of great value in the quest of explaining transport phenomena through cell membranes. It is furthermore of growing interest within the pharmacological research and contributes to the apprehension of life at the molecular level. In this thesis Molecular Dynamics has been used to simulate how evenly distributed phospholipids solvated in water leads to the formation of monolayers. An automation program has been written in Python for performing these simulations and is to be used as the foundation for performing simulations in further studies. The program was used to simulate model systems of high- and low concentrations of DPPC lipids. The DPPC lipid, like most other lipids, consist of a hydrophilic "head" part and two lipophilic "tails", which is the main cause of the lipids interacting in such a manner that forms membranes. The low concentration system was simulated for a total of 3 ns with all lipids having reached the surface at 1.5 ns, and the all lipids in the high concentration system had risen at 41 ns with a total simulation time of 43 ns.De mest grundläggande egenskaperna hos cellmembran kan förstås genom att studera hur dessa bildas. Detta skapar en bra grund för forskning relaterad till hur membranen interagerar med organiska molekyler och joner; något av stort värde i bemödandet att förklara transportfenomen genom cellmembran. Dessutom är det av växande intresse inom den farmakologiska forskningen och bidrar till kunskapen om liv på den molekylära nivån. I denna avhandling har Molekylär Dynamik använts för att simulera hur jämnt fördelade fosfolipider lösta i vatten leder till bildandet av monoskiktade membran. Ett automatiseringsprogram har skrivits i Python för att utföra dessa simuleringar och ska komma att användas som grund för genomförandet av simuleringar i vidare studier. Programmet användes för att simulera modellsystem med höga och låga koncentrationer av DPPC lipider. DPPC lipiden, liksom de flesta andra lipider, består av en hydrofil ''huvud'' -del och två lipofila ''svansar'', vilket är den huvudsakliga orsaken till att lipiderna interagerar på ett sådant sätt som driver bildandet av ett membran. Lågkoncentrationssystemet simulerades i totalt 3 ns, varav 1,5 ns behövdes för att alla lipider skulle nå vattenytan. Alla lipider i högkoncentrationssystemet hade kommit upp till ytan efter 41 ns och för detta system utfördes simuleringen under en total tid på 43 ns.
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周, 哲. "NMR studies of phospholipids and liposomal membranes." Kyoto University, 1997. http://hdl.handle.net/2433/202364.
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Rosenberger, Thad A. "Ether phospholipid metabolism in the adult awake rat : a model to study the role of ether phospholipids in brain /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488193272067084.
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Hubert, Florence. "Synthèse enzymatique de phospholipides structurés riches en DHA." Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1009/document.
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Ce travail étudie l’obtention de phospholipides structurés enrichis en DHA et en acide caprylique (PC DHA-C8) par voie enzymatique. Deux voies de synthèse sont étudiées, l’acidolyse et l’estérification. Suite à un criblage enzymatique, la lipase retenue pour les deux voies de synthèse est TL-IM. Une optimisation des paramètres de la réaction d’acidolyse a été réalisée entre l’acide caprylique (C8:0) et la phosphatidylcholine de tournesol (PC) par le biais d’un plan d’expériences. Les conditions optimales déterminées sont une température de 38°C, une activité de l’eau de 0,7, une quantité d’enzyme de 15% de la masse en substrat ainsi qu’un rapport molaire C8:0/PC de 18. Ces conditions ont ensuite été utilisées pour l’acidolyse de phospholipides microalgaux riches en DHA issus de la microalgue Tisochrysis lutea afin d’obtenir de la PC DHA-C8. Les résultats n’ont pas été concluants. L’autre voie de synthèse étudiée est l’estérification par des lipases de la GPC, de l’acide caprylique et du DHA en milieu fondu. Cette réaction a été optimisée par la technique du pas par pas. Les paramètres étudiés sont la température, la quantité d’enzyme, le rapport molaire GPC/C8:0/DHA et l’application d’un vide. Pour l’obtention de PC DHA-C8, il faut fixer chacun de ces paramètres respectivement de la sorte : 45°C, 20% d’enzyme, un rapport molaire de 1/3/15 et un vide de 100 mbar. La production de PC DHA-C8, bien qu’optimisée ne dépasse pas 2% de rendement. Cependant, durant cette expérience, il a été constaté une forte production de LPC DHA, atteignant 16% sans optimisation des paramètres de synthèseThe enzymatic synthesis of structured phsopholipids enriched in DHA and caprylic acid (PC DHA-C8) is studied. Two different ways are studied, acidolysis and esterification. An enzymatic screening led to the choice of the immobilized lipase from Thermomyces lanuginosa (TL-IM) for the 2 reactions. Parameters of the acidolysis reaction between carpylic acid (C8:0) and sunflower phosphatidylcholine (PC) were optimized by means of an experimental design. The optimum conditions determined are a temperature of 38°C, an aw of 0.7, an amount of enzyme of 15% of the mass of substrate and a molar ratio of C8:0/PC of 18. These conditions were applied to the acidolysis of microalgal phospholipids from T. lutea, rich in DHA, in order to produce PC DHA-C8. The other studied reaction is the lipase catalyzed esterification of GPC with C8:0 and DHA in a solvent-free medium This reaction has been optimized by studying each factor independently. The parameters studied are the temperature, the amount of lipase, the molar ratio GPC/C8:0/DHA and the use of reduced pressure. In order to obtain PC DHA-C8, each of theses parameters are respectively set at: 45°C, 20% of enzyme, a molar ratio of 1/3/15 and a pressure of 100 mbar. The production of PC DHA-C8, although optimized, does not exceed a yield of 2%. However, during this experiment, a high production of LPC DHA is observed, up to 16% without optimization of the synthesis parameter
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Wat, Chi Ling Elaine. "Dietary milk phospholipids and their effects on cardiovascular risk factors / Chi Ling Elaine Wat." Thesis, The University of Sydney, 2009. https://hdl.handle.net/2123/28853.
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Cardiovascular disease is responsible for a significant portion of morbidity and mortality in Australia. The metabolic syndrome, which is the clustering of cardiometabolic risk factors, is well known to be associated with increased risk of CVD. There is thus great interest in treating and preventing this metabolic disease. Pharmaceutical approaches
to the treatment of the metabolic syndrome to this date have been inadequate. Increasing evidence suggests that dietary PLs may be potentially cardioprotective. The aim of this thesis is therefore to investigate the possibility that PLs can be extracted from dairy milk, and to identify and characterise the potent ability of dairy milk PLs to
be used to treat and/or prevent CVD.
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Nagaraju, Shastri Shilpa. "La CDP-DAG synthase et la régulation de la synthèse des phospholipides chez Plasmodium falciparum." Montpellier 2, 2009. http://www.theses.fr/2009MON20120.
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Les phospholipides (PL) sont indissociables de la croissance des Plasmodies, parasites responsables du paludisme, que ce soit pour leur biogenèse membranaire, la signalisation ou le trafic cellulaire. Leur synthèse peut être d'intérêt pharmacologique que si elle est particulière en regards de l'hôte. Ces études ont eu pour but de caractériser la CTP- acide phosphatidique cytidyltransferase (CDS) qui fournit le CDP-DAG, indispensable précurseur des phospholipides anioniques. L'enzyme CDS de P. Falciparum (PfCDS) possèdent une unique et longue extension N-terminale (N-PfCDS) de fonction inconnue qui est clivée. Par des études biochimiques, génétiques et de biologie cellulaire, nous montrons le caractère indispensable de cette extension N-terminale unique. Le clivage protéolytique de la CDS Pro-form est conservé dans les Plasmodies, mais le site de clivage précis n'a pu être déterminé. L'extension N-terminale est une protéine associée aux membranes et possédant une affinité pour les phospholipides anioniques. Elle est exportée à l'extérieur du parasite à la vacuole parasitophore. Cela renforce l'intérêt pour ce domaine N-terminale formée par protéolyse et qui parait essentiel. Nous avons découvert MAL7P1. 31, un autre gène possédant un domaine cytidylyltransferase transferase CTP-1 qui n'est partagée que par la CDS et les Dolichol kinase. La protéine correspondante Pf53 est retrouvée associée à la membrane de vésicules localisées dans le cytosol parasite, mais ne possède aucune des activités prédites comme le montre des études de complémentation entreprises chez des bactéries et la levure. Des études menées dans P. Berghei montrent que le gène n'est pas essential pour la croissance du parasite dans le sang. Un troisième travail s'est intéressé à la régulation des nombreuses voies de biosynthèses des PL chez Plasmodium. Une stratégie globale d'analyse in silico sur P. Falciparum révèle la présence d'un élément réactif à la choline et l'inositol (ICRE) qui pourrait être une séquence d'activation « Upstream » comme cela a été démontré chez la levure. Ceci ouvre de nouvelles perspectives pour des études de régulations des voies de biosynthèse des PL chez les Plasmodies, domaine encore totalement inexploréPhospholipids are inseparable from Plasmodium spp, the malaria causative parasites, for their growth, membrane biogenesis, cellular signaling and trafficking. P. Falciparum phospholipids synthesis is of pharmacological interest due to their peculiarity compared to the host. This study was aimed to unravel the CTP:phosphatidic acid cytidylyltransferase that provide CDP-DAG that plays a pivotal role as the sole source for anionic PL. P. Falciparum CDS (PfCDS) possess a unique long N-terminal extension (N-PfCDS) of unknown function which was shown to be proteolytically processed. By employing biochemical, genetic and cell biology techniques in P. Falciparum and P. Knowlesi, we show indispensability of cds gene and its unique N-terminal extension. The processing of proform CDS protein was conserved in Plasmodium spp, but precise cleavage site could not be determined. The unusual cleaved N-terminal extension is a membrane associated protein with affinity to anionic phospholipids and, surprisingly, is trafficked outside the parasite to the parasitophorous vacuole. This further underlines the interest for this proteolytically-formed essential domain which remains enigmatic. We discovered MAL7P1. 31, another gene possessing a CTP_transferase 1domain that is characteristic of CDS and dolichol kinase. The corresponding protein, Pf23, is a membrane associated protein localized in vesicle-like structures in the parasite cytosol, but was deceptive for both activities as studied by bacterial and yeast complementation. Studies carried out in P. Berghei also disclosed that MAL7P1. 31 gene was dispensable for parasite growth. A third work dealt with regulation of the bewildering intricate pathways that govern malarial phospholipid synthesis. A global in silico analysis revealed the presence of an Upstream Activating Sequence controlled by inositol (UASINO) in the promoters of P. Falciparum genes, which is shown to mediate regulation of phospholipids synthesis in yeast. This opens new perspectives in regulation of Plasmodium phospholipids metabolism, which, so far, has remained untouched
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Lo, Ka-kin. "Characterization of phospholipid transfer protein (PLTP) in hepatocellular carcinoma." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557200.
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Winger, Theodore Medard. "Synthetic phospholipid-peptide conjugates : biomolecular building blocks for receptor activating structures." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/9505.
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Graham, Ian Stanley. "Experimental and theoretical investigations of charged phospholipid bilayers." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75664.
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Lipid systems containing charged species are examined by both experiment and theory. Experimental studies of the mixing of phosphatidylcholine or phosphatidylethanolamine with phosphatidic acid show that calcium induces fast ($ leq$1s) phase separation of these otherwise miscible systems, and that this can occur in an isolated bilayer. Ionogenic behaviour is theoretically investigated using a new electrolyte model which explicitly includes both the solvent and particle sizes, and a binding model which uses Guggenheim combinatorics to treat non 1-1 binding stoichiometries. This work predicts a reduced dielectric constant near charged surfaces and strong repulsive forces between closely spaced ($<$15A) surfaces. A reanalysis of data from charged monolayers experiments indicates (1) that the new electrolyte model describes double layer behaviour at high surface charge densities better than the traditional Derjaguin - Landau - Verwey - Overbeek (DLVO) theory, (2) that calcium and magnesium bind to phosphatidylserine monolayers with a 1-1 stoichiometry.
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Kaufmann, Stefan. "Charge transfer through layers of self-assembling molecules : double-layer studies." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359049.
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Assaf, Shereen Mashhour T. "Novel vesicles from surfactant mixtures for use in topical drug delivery." Thesis, University of Strathclyde, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249032.
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Smeets, Edgar Felix. "Scrambling of membrane phospholipids in platelets and erythrocytes." [Maastricht : Maastricht : Universiteit Maastrich] ; University Library, Maastricht University [Host], 1996. http://arno.unimaas.nl/show.cgi?fid=6693.
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Maunder, Karen. "Dietary modification of membrane phospholipids in breast disease." Thesis, University of Surrey, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291611.
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Kemball-Cook, G. "Interaction of factor VIII clotting protein with phospholipids." Thesis, Open University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375092.
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It was shown that addition of procoagulant phospholipid (PL) vesicles to F.VIII concentrate protected F.VIII:C from anti-F.VIII:C antibody inactivation, and that of the naturally-occurring PLs only phosphatidylserine (PS)-containing PL had this ability. By using a PL-F.VIII mixture as immunoadsorbent for anti-F.VIII:Ag 125I-Fab' label, an immunoradiometric assay (IRMA) for F.VIII:Ag was set up which showed sensitivity to the binding of the antigen to PL vesicles: studies showed that only PS and phosphatidic acid (PA) vesicles could bind F.VIII:Ag, and ultracentrifugation of F.VIII-PL mixtures confirmed their physical association. The PL-fractionation method for IRMA label preparation was further refined, supplying two different pools of anti-F.VIII:Ag antibody: one (PL-site) directed only against PL-binding sites on the antigen, the other against other epitopes of F.VIII:Ag. Competition studies with the non-PL-site label showed that both purified F.IXa and F.X interacted with F.VIII:Ag in the presence of procoagulant PL and Ca2+ ions. Studies using the PL-site label (a specific assay for F.VIII-PL binding) confirmed that only the negatively-charged PS and PA were highly active in binding F.VIII:Ag, zwitterionic PLs being inactive: also, the Kd of the F.VIII-PS interaction decreased sharply with increasing proportion of PS in the vesicle. Further investigations using free-flow electrophoresis demonstrated a strong correlation between the Kd for F.VIII-PL and the net (negative) surface charge of the vesicles. However it was also shown that neither negative charge nor PS head-group alone were sufficient to bind F.VIII:Ag: both had to be present. Assay of the PL-site antibody for anti-F.VIII:C activity confirmed that the PL-binding site on F.VIII:Ag plays an important part in the protein's procoagulant function: both SDS-PAGE analysis of F.VIII:Ag/PL-site label complexes and IRM assays of purified F.VIII peptides with the two antibody pools indicated that the PL-binding site is on the 80kD light chain of the factor VIII molecule.
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Alvis, Simon. "Interactions of phospholipids with the potassium channel KcsA." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417416.
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Ma, Xin. "The interaction between amyloid beta peptide and phospholipids." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/29637.
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The aim of the thesis project was to examine what form(s) of Amyloid beta (Aβ) (25-‐35) peptide interact with phospholipids in vitro and the implications of this for the mechanism of Alzheimer’s Diseases (AD). The mechanism of AD is thought to involve protein folding and misfolding. An increasing amount of evidence has shown that protein misfolding plays an important role in the biological and pathological processes of AD. Although seen as the biomedical markers of those diseases, the roles of amyloid aggregates themselves are still not fully understood. Whether the aggregates, or the monomer, or some other intermediates of Aβ cause AD is still unknown. In order to investigate the membrane-‐interaction of Aβ and its implications for AD, two forms of Aβ, namely levorotary and dextrorotary (L-‐ and D-‐) Aβ isomers were used. Evidence has shown that L-‐ and D-‐ peptide can each form aggregates in a humid environment. However, when mixed together, L-‐ and D-‐ peptides tend not to form any aggregates. Using the mixtures of L-‐ and D-‐ peptides at different proportions and as well as using L-‐ and D-‐ alone can help us to determine the toxic form of Aβ. Phospholipids have been used to mimic membrane bilayers. Biological membranes in vivo are a complicated system. They contain three types of lipids, namely phospholipids, glycolipids, and steroids. Different types of cells and different membranes have different proportions of those lipids. Studying the interaction between Aβ and membranes in vivo can be extremely difficult. Artificial membranes, which only contains one kind of lipids, on the other hand, are a useful tool for the study of molecular interactions. Phospholipids are the most abundant type of membrane lipid and thus that can be seen as representative of cell membranes. The interactions of Aβ and different kinds of phospholipids have been investigated in this project. This thesis discusses the secondary structure of Aβ in different environment, the interaction between Aβ and phospholipids at the air-‐water surface, and the location of Aβ in membranes during the interaction. The study provides useful information of the mechanisms and the origin of AD. At the end of the thesis, a discussion chapter analyses the difficulties of studying Aβ and AD and the potentials and inadequacies of this research.
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Du, Xiaosong. "Adsorption Studies of Polysaccharides and Phospholipids Onto Cellulose." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/30161.
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Interactions between biomolecules and cellulose films at solid/liquid interfaces was studied by surface plasmon resonance spectroscopy (SPR), quartz crystal microbalance with dissipation monitoring (QCM-D) and in situ atomic force microscopy (AFM) measurements. This dissertation shows the porous character of nanocrystalline cellulose films as the key feature for enhanced adsorption of chemically modified polysaccharides and provides quantitative analysis of polymer supported phospholipid structures as a stable platform for studying membrane-related processes.
Smooth cellulose I films were prepared by spincoating cellulose nanocrystal suspensions onto positively charged self-assembled monolayers on gold. The adsorption of pullulan cinnamate (PC) onto cellulose surfaces increased with increasing degree of cinnamate substitution. The interactions between PCs with higher degree of substitution (DS) and porous nanocrystalline cellulose (NC) films presumably generated looped multilayer PC structures that adsorbed more than twice as much onto NC films than onto regenerated cellulose (RC) films. PC chains not only covered the NC surface but also penetrated into the porous film. The porous features of NC film are responsible for the greater adsorption of polymer chains relative to tightly packed RC films.
Adsorption of phospholipid vesicles onto RC and NC films was also studied. Aggregates of intact vesicle were observed on NC surfaces with high water content ~ 84 % by mass. Phospholipid patches with smooth features were found to assemble onto RC surfaces with a lower degree of hydration ~ 30 % by mass. Vesicle membrane breakage was triggered by a destabilizing agent, LysoPC. The great mass decrease, and changes in dissipation and degree of hydration for phospholipid structures after exposure to LysoPC corresponded to the transformation from vesicles to layered structures. Initial binding of LysoPC micelles to unruptured vesicles was clearly resolved in SPR, whereas the huge mass decrease associated with bound water hides the initial adsorption of LysoPC onto vesicles in QCM-D experiments. The intitial binding of LysoPC micelles onto vesicle membranes lasted for 200 seconds with a maximal increase of 14 % by mass prior to vesicle collapse.
The role of cholesterol in phospholipid interactions with model cellulose surfaces was also considered. Supported vesicle layers over RC surfaces were observed for vesicle membranes containing â ¥ 6.3 % by mole cholesterol, whereas phospholipid or phospholipid with lower cholesterol content formed disconnected lipid islands on RC surfaces. Meanwhile, intact vesicles were always observed on NC surfaces for phospholipid/cholesterol blends regardless of the cholesterol content. The intact vesicles on cellulose surfaces were attributed to the ability of cholesterol to accommodate vesicle deformation.
These studies showed the impact of mesoscale structure of cellulose films on adsorbates. It sheds light on the role of the lignin-carbonhydrate-complex in plant cell wall structure and will inform the next generation of biomimetic nanocomposites. The designed polymer supported biomimetic membranes provide a perfect platform to develop intact and ruptured protoplast systems for the study of plant cell wall self-assembly.Ph. D.
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Campbell, Darren. "Tear and skin phospholipids analysis and hydrogel analogues." Thesis, Aston University, 2007. http://publications.aston.ac.uk/9807/.
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This thesis is concerned with the analysis of phospholipids in the tear film and with the synthesis of phospholipids analogous to hydrogels. The work consists of two areas. The first area is the study of the phospholipids in the tear film, their nature and fate. The use of liquid chromatography mass spectrometry determined that the concentration of phospholipids in the tear film was less than previously thought. Thin layer chromatography showed the presence of diacylglycerides (DAGs) in the tear film at relatively high concentrations. The activity of an enzyme, phospholipase C, was found in the tear film. It was hypothesised that the low concentration of phospholipids and high concentrations of DAG in the tear film was due to the action of this enzyme. The second area of study was the synthesis of phospholipids analogous materials for use in ocular and dermal applications. For ocular applications the synthesis involved the use of the monomer N,N-dimethyl-N-(2-acryloylethyl)-N-(3-sulfopropyl) ammonium betaine (SPDA) in combination with 2-hdyroxyethyl methacrylate (HEMA). Charge-balanced membranes were also synthesised using potentially anionic monomers in conjunction with cationic monomers in stoichiometrically equivalent ratios also with HEMA as a commoner. Membranes of SPDA copolymers and charge-balanced copolymers proved to have some properties suitable for ocular applications. The dermal materials consisted of one family of partially hydrated hydrogels synthesised from SPDA in combination with ionic monomers: sodium 2-(acrylamido)-2-methyl propane sulfonate and acrylic acid-bis(3-sulfopropyl)-ester, potassium salt. A second family of partially hydrated hydrogels was synthesised from N-vinyl pyrrolidone. Both of the partially hydrated hydrogels synthesised proved to have some properties suitable for use as adhesives for the skin.
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Wang, Guang. "Phospholipids oxidation and foaming enhancement of egg albumen." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3389160.
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Bourgeois, Christine. "Influence de la structuration de l'interface colloïdale sur la formulation et la biodisponibilité d'acides gras d'intérêt nutritionnel." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0379/document.
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Les études épidémiologiques récentes montrent une consommation insuffisante d’acides gras polyinsaturés (AGPI) dans les pays occidentaux. Cependant, la sensibilité des AGPI à l’oxydation est l’une des premières causes de détérioration des qualités organoleptique et nutritionnelle dans les produits alimentaires. Parallèlement, les lipides présents dans les produits alimentaires se trouvent le plus souvent sous forme émulsionnée. Ainsi, les entreprises désirant formuler des produits alimentaires enrichis en AGPI adoptent des stratégies technologiques pour les stabiliser chimiquement et physiquement, tout en assurant leur biodisponibilité. Une de ces stratégie consiste à rechercher, dans la nature, des systèmes émulsifiés stables afin d’en extraire des molécules tensioactives d’intérêt et de mimer l’organisation des lipides. C’est dans ce contexte que des études portent, depuis quelques années, sur les corps lipidiques (Oil Bodies, OB), structures végétales naturelles de stockage des lipides des plantes oléagineuses, composées de phospholipides (PL) et de protéines (OBP).L’objectif général de ce projet de thèse vise à maitriser la formulation d’émulsions préparées uniquement à base de colza (huile, PL et OBP) par une meilleure connaissance des interactions PL : OBP, d’étudier la stabilité des émulsions d’un point de vue physicochimique en conditions de stockage et dans des conditions mimant les conditions gastro-intestinales et, enfin, d’évaluer l’influence de la composition de l’interface des émulsions sur la bioaccessibilité des acides gras insaturés in vivo chez le rat.Les études spectroscopiques des interactions PL modèles : OBP ont mis en évidence des interactions favorables à la stabilisation des émulsions entre les PL anioniques, les PL insaturés et les OBP. Ces résultats ont orienté le choix vers une lécithine de colza spécifique. Les interactions PL : OBP, modulées par le pH et le rapport PL : OBP, influencent la réalisation des émulsions, la quantité d’OBP adsorbées à l’interface et la stabilité physique des émulsions, avec un crémage prononcé pour les émulsions riches en protéines. La synergie PL : OBP à l’interface semble être un facteur décisif pour ralentir l’oxydation de l’huile de colza émulsifiée. Le comportement des émulsions, dans des conditions mimant celles du milieu gastro-intestinal, montre que la présence d’OBP à l’interface favorise la floculation des émulsions à pH acide (mimant celui de l’estomac), mais que cette floculation est réversible lorsque le pH est ramené à des valeurs proches de celle de l’intestin. La présence des OBP favorise l’activité de la lipase pancréatique in vitro. Finalement, l’interface composée de PL et d’OBP améliore la bioaccessibilité lymphatique des AGPI in vivo chez le rat.En conclusion, nous avons montré qu’il est possible de formuler des émulsions uniquement à base de colza. Elles pourraient présenter une alternative intéressante aux émulsions stabilisées par des émulsifiants d’origine synthétique (politique clean label) ou d’origine animale (alimentation végane)Recent epidemiologic studies show an insufficient intake of polyunsaturated fatty acids (PUFA) in occidental countries. Besides, the sensibility of PUFA to oxidation is one of the major causes of organoleptic and nutritional quality deterioration in food products. Moreover, lipids in food products are often in an emulsified stage. Therefore, industrials that care to formulate PUFA enriched food products adopt technological strategies to protect and stabilize the lipids while improving their bioavailability. One of those strategies consists in looking for stable emulsified systems that already exist in nature, extract tensioactive molecules of interest and mimic the lipid state. In this context, several studies deal with oil bodies (OB), that are natural occurring structures for lipid storage in oleaginous plants, composed of proteins (OBP) and phospholipids (PL).Therefore, the main objective of this PhD work is to manage emulsion formulation only based on canola (oil, PL and OBP). This goes through: 1) an understanding of the interactions between PL and OBP; 2) a study of the stability of the emulsions under storage and gastrointestinal conditions, and finally, 3) an investigation of the influence of the emulsion interfacial composition on the bioavailability of PUFA in rats.The spectroscopic studies of the model PL:OBP interactions showed favorable interactions for stabilizing the emulsions based on anionic PL, unsaturated PL and OBP. These results allowed choosing an adequate canola lecithin. The PL:OBP interactions, modulated by the pH and the PL:OB ratio, influences the formation of the emulsions, the quantity of OBP adsorbed at the interface and the physical stability of emulsions with a pronounced creaming in emulsions rich in proteins. The PL:OBP synergy at the interface seems to be a decisive factor to slow down the oxidation of the emulsified canola oil. The emulsion behavior in conditions that mimic that of the gastrointestinal track, shows that the presence of OBP at the interface favored the emulsion flocculation at acid pH (mimicking that of the stomach). However, the flocculation was reversible when the pH was adjusted to a value close to that of the intestine. OBP also increased the activity of the pancreatic lipase in vitro. Finally, the presence of PL and OBP at the interface increased the lymphatic bioaccessibility of the PUFA in rats.On the whole, we showed that it is possible to manage emulsion formulation only based on canola products. This could be of peculiar interest for clean labeling or vegan nutrition by subtracting synthetic emulsifiers or emulsifiers from animal origin, respectively
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Mason, Peter C. "Small angle scattering studies of phospholipids in excess water." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0023/NQ51003.pdf.
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Mason, Peter C. "Small angle scattering studies of phospholipids in excess water /." *McMaster only, 1998.
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Taylor, T. M. C. "Modified phospholipids : Oxidation promoted by vesicle-bound metal ions." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382664.
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Yu, Rong. "Metabolic interactions among amino acids, phospholipids and fatty acids." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45211.
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Cystic fibrosis (CF) is the most common life-shortening disorder among Caucasians. Excessive faecal bile acid loss, increased oxidant stress, reduced plasma choline, increased oxidant stress, reduced glutathione and alterations in essential fatty acids are well recognized in patients with CF. It is also well-known that diabetes perturbs the methionine-homocysteine cycle. However, experimental data linking loss of amino acids in CF or decreased glucose availability in experimental diabetes to altered phospholipids and fatty acid metabolism are lacking. In the liver, bile acids are conjugated with glycine or taurine prior to secretion, and glycine de novo synthesis begins with glucose. Thus, the objectives of this thesis are: 1) to determine if inducing faecal bile acid loss will alter the methionine-homocysteine, and choline-betaine cycle metabolites, phospholipids and phospholipids n-6 and n-3 fatty acids, and 2) to show that experimental diabetes, which decreases glucose availability, alters methionine-homocysteine and choline-betaine cycle metabolites, phospholipids and phospholipid fatty acids in rats.
Studies to address the first objective demonstrated that inducing faecal bile acid malabsorption leads to fat malabsorption with increased faecal total lipids and phospholipid excretion. This increased excretion was accompanied by increased plasma betaine concentration, decreased plasma triacylglycerol concentration, increased plasma and liver S-adenosylhomocysteine (SAH) concentration, and changes in the fatty acid composition of hepatic phospholipids. Studies to address the second objective showed that experimental diabetes led to increased plasma betaine concentration, decreased homocysteine concentration, increased liver phosphatidylethanolamine, decreased phosphatidylcholine, changes in the fatty acid composition of hepatic phospholipids, and abundance of the enzyme choline dehydrogenase. Thus, experimental diabetes, which reduces intracellular glucose availability, alters methionine-homocysteine and choline-betaine cycle metabolites, phospholipids and fatty acids. In conclusion, metabolism of phospholipids, their fatty acids, and the amino acids involved in the methionine-homocysteine cycle are inter-related.
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Buckland, Andrew G. "Anionic phospholipids, annexins and the activity of phospholipases A2." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246259.
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Stanley, R. J. "Mathematical models of signalling through G proteins and phospholipids." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1472846/.
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G proteins and phospholipids are two major classes of signalling molecule. ey are each-independently and together-involved in diverse 'signalling pathways' - bio- chemical networks through which cells maintain healthy responses to stimuli. A unique 'cross-talk motif' is formed by regulation of the phospholipid-modifying enzymes phospholipase D (PLD) and phosphatidylinositol 4-phosphate 5-kinase (PI4P5K) by the Arf family of small G proteins and-curiously-each other's product. Here, understanding of this inherently complex motif has been strengthened by the development and analysis of mathematical models, specifically systems of ordinary differential equations (ODEs). Construction of simple empirical models suggests asymmetry in the mechanisms of regulation of the enzymes is responsible for production of two distinct outgoing signals from a single input signal, one displaying threshold activation behaviour. Additionally, well-defined quasi-steady-state (QSS) mechanistic models (à la Michaelis- Menten) have been developed for each of: PLD; PI4P5K; and G protein/Arf regula- tion. During this process-due to insufficient pre-existing descriptions-biochemically- plausible assumptions were required for certain regulatory and catalytic interactions. Analysis of the G protein regulation models establishes that-contrary to previous representations-this regulation is best described by a balance/unbalance mechanism, where observed activation absolutely requires the presence of the inactivator. Together, the QSS models can be combined to form a complete model of the Arf/PLD/ PI4P5K motif suitable for computational simulation - preliminary parameters show that this model is capable of displaying physiologically-plausible behaviours ese results give a be er understanding of the signalling role of the Arf/PLD/PI4P5K motif; lead to novel biological hypotheses amenable to later experimental validation; highlight where our current biological understanding of the system is insufficient; and suggest novel methods for the therapeutic control of G proteins.
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Politino, Michael. "Calcium- and calmodulin-sensitive interactions of calcineurin with phospholipids /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487672245903115.
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Li, Qiong Medical Sciences Faculty of Medicine UNSW. "Lipid analysis of wild type and caveolin-1 knock out mouse embryonic fibroblasts." Awarded by:University of New South Wales. Medical Sciences, 2008. http://handle.unsw.edu.au/1959.4/41552.
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The aim of this project is to characterise the levels of cholesterol and phospholipid in cell homogenates, plasma membranes and isolated membrane domains from wildtype (WT) and caveolin-l knock-out (Cav-1-/ -) mouse embryonic fibroblasts (MEFs). Quantitative lipid analysis was developed for cholesterol by high-performance liquid chromatography (HPLC) and for glycerophospholipids (GPL) and sphingomyelin (SM) by electrospray ionisation mass spectrometry (ESI-MS). In the cell homogenates, by comparing WT to Cav-l-/- MEFs, it was found that the total cholesterol as well as the proportions of the main GPLs such as Phosphatidylcholines (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) was similar in both cell types. However, Cav-l-/- MEFs have higher levels of cholesterol esters than WT MEFs in whole cell homogenate. Furthermore, the proportion of SM is higher in Cav-l-/- than WT MEFs. These data suggest that Cav-l may control the balance between free and esterified cholesterol and is involved in SM metabolism. A small increase in SM level in Cav-l-/- compared to WT plasma membrane was observed but this increase was not significant. Similarly, cholesterol levels in the plasma membrane are comparable between the two cell types. In both cell types, the levels of SM and phosphatidylglycerol (PG) are higher in the plasma membranes than in cell homogenates. In the WT cells, PE levels are higher in the plasma membrane than in the cell homogenates. While in the Cav-1-/- cells, the level of free cholesterol and PC are higher in the plasma membrane compared to the cell homogenate. PCs are the predominant lipids in both cell types. Cav-1-l - cells have more saturated fatty acyl chains in their PC species and shorter carbon chains compared to WT MEFs and this trend was found in both cell homogenate and plasma membranes. In PEs and SMs, Cav-1-/ - cells also have higher levels of saturated PEs and saturated amide-linkage SM than in WT cells, respectively. The results indicate that Cav-1 may also play a role in fatty acids metabolism. In summary, the data from this work indicate that Cav-l expression affects lipid composition in MEFs including the relative distribution of free and esterified cholesterol, the levels of SM relative to other phospholipid subclasses and the incorporation of fatty acids into phospholipids.