Добірка наукової літератури з теми "DiPalmitoyl PhosphatidylGlycerol"

Abstract By means of differential thermoanalysis, the miscibility of the main polar tetraether lipid of Thermoplasma acidophilum with two ester lipids, dipalmitoyl phosphatidylcholine and dipalmitoyl phosphatidylglycerol, resp., in the presence of excess water was studied. It is shown that with increasing fraction of tetraether lipid in the mixture, the transition range of dipalmitoyl phosphatidylcholine is broadened and the temperature of the maximum heat flow (Tm) is shifted to lower temperatures; furthermore, the enthaply change (ΔH) of the transition declines. Similar results were obtained with mixtures of tetraether lipid with dipalmitoyl phosphatidylglycerol. It is therefore concluded that the main polar tetraether lipid of Thermoplasma acidophilum , which essentially forms monomolecular layers, is able to form stable common phases with bilayer-forming ester lipids. Miscibility of the tetraether lipid with dipalmitoyl phosphatidylglycerol, which are both monovalent anions at neutral pH, is also observed in the presence of high proton or calcium ion concentrations.

It is not yet completely understood how a cell is able to export specific phospholipids, like dipalmitoylphosphatidylcholine (dipalmitoyl-PC), which is secreted by pneumocytes type II, into pulmonary surfactant. The acyl species composition of [3H]PC which was synthesized in type II cells in the presence of [2-3H]glycerol resembled the species composition of PC localized in intracellular pneumocyte membranes. This species pattern was different from the pattern of PC of lamellar bodies, i.e., intracellularly stored surfactant, by a higher proportion of dipalmitoyl-PC mainly at expense of 1-palmitoyl-2-oleoyl-PC. Lamellar body PC in turn showed the same species distribution as surfactant PC. The data suggest that subcellular compartmentation and/or intracellular transfer of PC destined to storage in lamellar bodies, but not secretion of lamellar bodies, involves an enrichment of dipalmitoyl-PC and a depletion of 1-palmitoyl-2-oleoyl-PC. In contrast, the acyl species pattern of phosphatidylglycerol does not seem to undergo gross changes on the path from synthesis to secretion.

Phospholipid lining, present at the respiratory mucus-mucosa interface, may have an important role in the protective function of the airways by its abhesive properties and may also facilitate mucus transport. To mimic respiratory mucus-mucosa interface, monolayers of three different forms of phosphatidylglycerol (PG) have been deposited on glass slides by the Langmuir-Blodgett technique. Mucus adhesion and clearance by cough of mucus on these PG-coated or noncoated surfaces have been analyzed and compared, using frog respiratory mucus as “normal” mucus. Among the three PG types studied, the phosphatidylglycerol distearoyl, which is the phospholipid with the longest saturated fatty acid chain, was found to significantly improve the mucus cough clearance by decreasing the mucus work of adhesion compared with the noncoated surfaces. On the other hand, phosphatidylglycerol dipalmitoyl did not improve mucus cough clearance although it decreased mucus adhesion, and phosphatidylglycerol dioleyl did not improve either mucus cough clearance or mucus adhesion.

Binding isotherms of N-phenyl-1-naphthylamine to different lipid monolayers are obtained by use of fluorescence spectroscopy for different surface pressures. In the case of dipalmitoyl phosphatidylcholine, the affinity is high in the liquid expanded state, but drops in the liquid condensed state. The affinity for the negatively charged dilauryl phosphatidylglycerol is very low. In the case of phosphatidylethanolamine extracted from Escherichia coli, a strong decrease in the affinity is detected about 20 mN/m. This can be explained by an increase of interactions between the molecules of the lipid matrix. These data lead to the conclusion that the packing is not uniform in sonicated vesicles.Key words: monolayer, phospholipid, fluorescence, phase transition.

The applicability of full-q-range models to fit low-resolution X-ray diffraction data from multibilayers exhibiting only weak quasi-Bragg peak scattering has been analysed. The models consider different structure factors, accounting for different types of lattice disorder caused by stacking faults or bending fluctuations. Numerical tests of the models, considering instrumental influence of a line-focus collimation system, demonstrated that Bragg peak line shapes given by different lattice disorders cannot be discerned. However, line-shape parameters can be determined for a particular sample, if the type of disorder is knowna priori. This has been verified by comparing the experimental results for the fluctuation parameter of palmitoyl-oleoyl phosphatidylcholine (POPC) as a function of temperature with high-resolution data on the same lipid. Tests further show that the calculation of structural parameters, such as the membrane thickness or the extent of the interbilayer water region, is not obscured by the smearing imposed by the instrument. The model was further applied successfully to experimental data of lipid mixtures composed of sphingomyelin (SM)/POPC/cholesterol and dipalmitoyl phosphatidylethanolamine (DPPE)/dipalmitoyl phosphatidylglycerol (DPPG). The structural parameters determined give valuable insight into the physical state of the membrane system, which is not accessible when quasi-Bragg reflections only are considered.

The detection of trace amounts of phenothiazines with fast, direct methods is important for medical applications and the pharmaceutical industry. In this paper we explore the concept of an electronic tongue to detect methylene blue (MB), with a sensor array comprising 6 units. These units were a bare Pt electrode, and Pt electrodes coated with 1-layer LB films of dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG), a 5-layer LB film of stearic acid, and 10 nm PVD films of bis benzimidazo perylene (AzoPTCD) and iron phthalocyanine (FePc). The electrical response obtained with impedance spectroscopy varied with the sensing unit, in spite of the small film thickness, thus indicating good cross-sensitivity. Upon treating the capacitance data at 1 kHz with Principal Component Analysis (PCA), the sensor array was capable of distinguishing MB solutions from ultrapure water down to 1 nM. This unprecedented high sensitivity was probably due to strong interactions between MB and DPPC and DPPG, as the sensing units of these phospholipids gave the most important contributions to the PCA plots. Such strong interaction was not manifested in the surface pressure–area isotherms of co-spread monolayers of MB and DPPC or DPPG, which emphasizes the high sensitivity of the electrical measurements in ultrathin films in contact with liquids, now widely exploited in electronic tongues.

The subcellular site of phosphatidylglycerol (PG) formation for lung surfactant has not been convincingly clarified. To approach this problem we analysed the acyl species pattern of lung PG in mitochondria, microsomes and surfactant by h.p.l.c. separation of its 1,2-diacyl-3-naphthylurethane derivatives. Both mitochondrial and microsomal PG proved identical with surfactant PG, containing the major species 1-palmitoyl-2-oleoyl-PG and 1,2-dipalmitoyl-PG. The fatty acid composition of mitochondrial PG differs markedly from that of diphosphatidylglycerol. This may be taken as an indication that mitochondrial PG is synthesized on purpose to form surfactant, rather than being only the precursor of diphosphatidylglycerol. In vitro, sn-[U-14C]glycerol 3-phosphate incorporation into PG of mitochondria or microsomes occurs in the presence of CTP, ATP and CoA but independently of the supply of exogenous lipoidic precursors. Although the rate in vitro of autonomous PG synthesis, and the endogenous PG content, are higher in mitochondria than in microsomes, it is assumed that both subcellular fractions are involved in PG formation for surfactant.

Après l'éradication de la variole déclarée par l'OMS en 1980 grâce à la vaccination, la réémergence de la variole dans un contexte de menace bioterroriste est possible, ainsi une meilleure compréhension des phénomènes d'infection par les orthopoxvirus est nécessaire. Ainsi ce travail de thèse s'inscrit dans le cadre d'un programme de « développement de contre-mesures médicales contre la variole », par l'étude des mécanismes d'infection et d'immunité. La transmission du virus de la variole ayant lieu par voie respiratoire, il est primordial d'étudier les mécanismes d'entrée du virus dans les poumons et les facteurs protéiques et lipidique impliqués lors de ce mécanisme d'entrée. La fonction d'immunité innée, portée par certains phospholipides présents dans le surfactant pulmonaire, a d'abord été étudiée. La découverte de cette fonction antivirale in vitro pour le DiPalmitoyl PhosphatidylGlycerol (DPPG) a conduit à l'évaluation de son activité in vivo dans un modèle d'infection pulmonaire chez la souris, ce lipide entraînant une protection importante dans un modèle létal. Par ailleurs, l'étude de l'interaction entre le virus de la vaccine et certains lipides présents dans les membranes cellulaires a permis de mettre en évidence un récepteur membranaire secondaire potentiel du virus de la vaccine assurant des fonctions similaires à celles des glycosaminoglycanes : le sulfatide. Enfin, l'étude des protéines de l'immunité innée, spécifiques du surfactant pulmonaire, a permis de mettre à jour l'existence d'une forte interaction entre la protéine SP-D et le virus de la vaccine. Cette interaction entraîne une inhibition de l'infection. Résultat qui reste à être confirmé lors de l'utilisation d'un modèle murin recombinant, KO pour cette protéine. Ces travaux démontrent l'intérêt à consacrer aux facteurs protéiques et lipidiques du surfactant et des membranes cellulaires et suggèrent la possibilité de l'utilisation de ces molécules, modifiées ou non, dans le développement et l'amélioration d'outils thérapeutiques et/ou prophylactiques pour traiter les infections par les poxvirus
Variola virus was declared eradicated in 1980 after a worldwide vaccination campaign. A better understanding of the infection process of orthopoxviruses is nevertheless necessary because of the potential release of variola by bioterrorists. Here we report potential counter-measures against Variola virus that could result from studying mechanisms of viral entry and immunity against Variola virus. The purpose of this work was to study multiple factors in vaccinia virus entry in the lung and thus gain a better understanding of the infectious process that could be used to stop infection by Orthopoxvirus. The innate immune functions displayed by some phospholipids (DiPalmitoyl PhosphatidylGlycerol) in lung surfactant were studied. The discovery of the ability of DPPG to inhibit vaccinia virus infection in cell culture led to the evaluation of its in vivo activity during a lethal vaccinia virus infection. Furthermore, the analysis of the interaction between vaccinia virus and plasma membrane lipids (sulfatide) enabled the definition of a secondary receptor for vaccinia virus in addition to glycosaminoglycans that were characterized previously. Finally, examination of the specific innate immunity provided by proteins in lung surfactant allowed us to highlight interactions between one surfactant protein (Surfactant protein D) and vaccinia virus. These interactions were then characterized as inhibitory interactions for vaccinia virus infection. Our findings underline the importance of lipids and proteins inlung surfactant as well as lipids in the plasma membrane in the Poxvirus infection and suggest that these molecules may be potential new targets for the development of new therapeutic and prophylactic products to efficiently treat poxvirus infection

In recent years, phosphatidylglycerol (PG) has been attracting attention in the field of cell physiology such as photosynthesis and germ cells, or clinical diagnosis. Most of phospholipids containing PG are analyzed using HPLC and LC-MS; however, it has been desired to develop an enzymatic assay method for determination of PG concentration in a simple, easy, and high-through put.In our presentation, biochemical characterization of a PG-specific phospholipase C (PG-PLC) from Amycolatopsis sp. NT115 will be reported. PG-PLC (molecular mass, 55 kDa) showed maximal activity at pH 6.0 and 55°C. PG-PLC showed almost no activity on other diacylphospholipids, dipalmitoylPG, lysoPG and glycerol 3-phosphate, demonstrating PG-PLC can recognize not only the substrate headgroup but also the acyl chains. PG-PLC was inhibited by Zn2+; however, it was hardly inhibited by EDTA and non-ionic surfactants such as Triton X-100, Tween 80, Briji 35 and Nonidet P-40. PG-PLC activity was enhanced by 1 mM Mn2+, Al3+, 0.1% sodium deoxycholate by 1.3-2.5 folds. Recombinant PG-PLC (rPG-PLC) was extracellularly produced using Streptomyces lividans/pUC702 expression system. However, unexpectedly it was produced with the N-terminal region deleted by ca. 230 amino acids. As a result, the stability of the deletion mutant (Δ230aa) was markedly decreased. In 96 h culture, rPG-PLC with His6-tag was produced with 0.188 U/mL and 3.36×10-2 U/mg-protein in the culture supernatant. Moreover, 1.52 mg-protein of the purified Δ220aa (2.5 U/mL, 16.4 U/mg-protein) was yielded from 0.9 L of the culture supernatant by His-tag affinity chromatography. Using the purified Δ220aa, kinetic parameters were determined to be Km=0.368 mM, 99.2 µM/min (6.51 mmol/min/mg-protein), kcat=5.29×10-2 s-1, kcat/Km=0.256 mM-1s-1 for POPG.