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Reproduction, Nutrition, Development 2004The molecular species composition of membrane phospholipids influences the activities of integral proteins and cell signalling pathways. We determined the effect of...
The molecular species composition of membrane phospholipids influences the activities of integral proteins and cell signalling pathways. We determined the effect of increasing gestational age on fetal guinea pig liver phosphatidylcholine (PC) and phosphatidylethanolamine (PE), and plasma PC molecular species composition. The livers were collected from fetuses (n = 5/time point) at 5 day intervals between 40 and 65 days of gestation, and at term (68 days). Hepatic PC and PE molecular species composition was determined by electrospray ionisation mass spectrometry. An increasing gestational age was accompanied by selective changes in individual molecular species. The proportion of the sn-1 18:0 species increased relative to the sn-1 16:0 species in liver PC, but not PE, with an increasing gestational age. 1-O-alkyl-2-acyl PC species concentrations decreased significantly between 40 and 45 days of gestation (40%), and 65 and 68 days (54%). Total 1-O-alkenyl-2-acyl PE species concentration increased between days 60 and 65, due to a rise in 1-O-16:0 alkyl/20:4 content, and then decreased until term. Between day 40 and term, PC and PE sn-2 18:2n-6 species concentrations increased 3-fold. PC16:0/18:2 increased gradually throughout gestation, while PC18:0/18:2 content only increased after day 65. The overall increase in PE18:2n-6 content was due to PE18:0/18:2 alone. The composition of plasma PC essentially reflected hepatic PC. Overall, these data suggest differential regulation of hepatic PC and PE molecular species composition during development which is essentially independent of the maternal fatty acid supply.
Topics: Animals; Female; Fetal Development; Gestational Age; Guinea Pigs; Liver; Phosphatidylcholines; Phosphatidylethanolamines; Phospholipids; Pregnancy; Spectrometry, Mass, Electrospray Ionization
PubMed: 15762301
DOI: 10.1051/rnd:2004060 -
Lipids Jan 2011High performance liquid chromatography-electrospray tandem mass spectrometry was used to elucidate the phospholipids in krill oil extracted from Euphausia superba, an...
High performance liquid chromatography-electrospray tandem mass spectrometry was used to elucidate the phospholipids in krill oil extracted from Euphausia superba, an emerging source for human nutritional supplements. The study was carried out in order to map the species of the choline-containing phospholipid classes: phosphatidylcholine and lyso-phosphatidylcholine. In addition, the prevalent phosphatidylcholine class was quantified and the results compared with prior analysis. The qualification was performed with separation on a reverse phase chromatography column, while the quantification was obtained with class separation on a normal phase chromatography column. An Orbitrap system was used for the detection, and pulsed-Q dissociation fragmentation was utilized for the identification of the species. An asymmetrical exclusion list was applied for detection of phospholipid species of lower concentration, significantly improving the number of species observed. A total of 69 choline-containing phospholipids were detected, whereof 60 phosphatidylcholine substances, among others seven with probable omega-3 fatty acids in both sn-1 and sn-2. The phosphatidylcholine concentration was estimated to be 34 ± 5 g/100 g oil (n = 5). These results confirm the complexity of the phospholipid composition of krill oil, and the presence of long chained, heavily unsaturated fatty acids.
Topics: Animals; Chromatography, High Pressure Liquid; Chromatography, Reverse-Phase; Euphausiacea; Fatty Acids, Omega-3; Oils; Phosphatidylcholines; Tandem Mass Spectrometry
PubMed: 20848234
DOI: 10.1007/s11745-010-3472-6 -
Biophysical Chemistry Feb 2015Nanolipoprotein particles (NLPs), also known as nanodiscs, are lipid bilayers bounded by apolipoprotein. Lipids and membrane proteins cannot exchange between NLPs....
Nanolipoprotein particles (NLPs), also known as nanodiscs, are lipid bilayers bounded by apolipoprotein. Lipids and membrane proteins cannot exchange between NLPs. However, the addition of bicelles opens NLPs and transfers their contents to bicelles, which freely exchange lipids and proteins. NLP-bicelle interactions may provide a new method for studying membrane protein oligomerization. The interaction mechanism was investigated by stopped flow fluorometry. NLPs with lipids having fluorescence resonance energy transfer (FRET) donors and acceptors were mixed with a 200-fold molar excess of dihexanoyl phosphatidylcholine (DHPC)/dimyristoyl phosphatidylcholine (DMPC) bicelles, and the rate of lipid transfer was monitored by the disappearance of FRET. Near or below the DMPC phase transition temperature, the kinetics were sigmoidal. Free DHPC and apolipoprotein were ruled out as participants in autocatalytic mechanisms. The NLP-bicelle mixing rate showed a strong temperature dependence (activation energy = 28 kcal/mol). Models are proposed for the NLP-bicelle mixing, including one involving fusion pores.
Topics: Apolipoproteins; Dimyristoylphosphatidylcholine; Fluorescence Resonance Energy Transfer; Kinetics; Lipid Bilayers; Membrane Fusion; Micelles; Models, Molecular; Phosphatidylcholines
PubMed: 25660392
DOI: 10.1016/j.bpc.2015.01.006 -
Journal of Lipid Research Nov 1971The initial rate of incorporation of methyl-labeled choline into the acid-soluble pool (phosphorylcholine) of Novikoff hepatoma cells growing in suspension culture was...
Choline metabolism and membrane formation in rat hepatoma cells grown in suspension culture. 3. Choline transport and uptake by simple diffusion and lack of direct exchange with phosphatidylcholine.
The initial rate of incorporation of methyl-labeled choline into the acid-soluble pool (phosphorylcholine) of Novikoff hepatoma cells growing in suspension culture was investigated as a function of the choline concentration in the medium. Below, but not above, 20 micro m, choline incorporation followed simple Michaelis-Menten kinetics at 24, 33, or 37 degrees C with an apparent K(m) of 4-7 micro m, and the V(max) values decreased with a Q(10) of about 2.3 with a decrease in temperature. Between 20 and 500 micro m, on the other hand, the rate of incorporation increased linearly with an increase in choline concentration in the medium, and the increase in incorporation rate with increase in choline concentration was about the same at all temperatures tested. The data suggest that at low concentrations choline is taken up mainly by a transport reaction, whereas at concentrations above 20 micro m, simple diffusion becomes the principal mode of uptake. The energy of activation for choline transport was estimated from an Arrhenius plot of the V(max) values as 67,000 J (16 kcal)/mole. At concentrations below 20 micro m, choline incorporation into membrane phosphatidylcholine also followed simple Michaelis-Menten kinetics, and the apparent K(m) was about the same as that for choline transport. The data support the conclusion that the transport of choline into the cell is the rate-limiting step in the conversion of choline to phosphorylcholine and its incorporation into phosphatidylcholine. At concentrations above 100 micro m, on the other hand, the ultimate rate of choline incorporation into phosphatidylcholine was independent of the choline concentration in the medium or the intracellular level of phosphorylcholine. Further, the rate of turnover of the choline moiety of phosphatidylcholine (half-life, 20-24 hr) either in whole cells or during incubation of isolated membrane fractions was unaffected by the presence of an excess of choline in the medium. The overall results indicate that a direct exchange between free choline and the choline moiety of phosphatidylcholine does not play a significant role in the incorporation of choline into phosphatidylcholine by Novikoff cells or in the turnover of the choline moiety of phosphatidylcholine, and that labeled choline therefore is a useful precursor in studying the synthesis and turnover of membrane phosphatidylcholine in these cells.
Topics: Animals; Biological Transport; Carcinoma, Hepatocellular; Cell Fractionation; Cell Line; Cell Membrane; Cell Membrane Permeability; Cells, Cultured; Choline; Diffusion; In Vitro Techniques; Kinetics; Liver Neoplasms; Oxidative Phosphorylation; Phosphatidylcholines; Rats; Time Factors; Tritium
PubMed: 4330925
DOI: No ID Found -
The Journal of Physical Chemistry. B Jun 2023Ethylenediaminetetraacetic acid (EDTA) is frequently used in lipid experiments to remove redundant ions, such as Ca, from the sample solution. In this work, combining...
Ethylenediaminetetraacetic acid (EDTA) is frequently used in lipid experiments to remove redundant ions, such as Ca, from the sample solution. In this work, combining molecular dynamics (MD) simulations and Langmuir monolayer experiments, we show that on top of the expected Ca depletion, EDTA anions themselves bind to phosphatidylcholine (PC) monolayers. This binding, originating from EDTA interaction with choline groups of PC lipids, leads to the adsorption of EDTA anions at the monolayer surface and concentration-dependent changes in surface pressure as measured by monolayer experiments and explained by MD simulations. This surprising observation emphasizes that lipid experiments carried out using EDTA-containing solutions, especially of high concentrations, must be interpreted very carefully due to potential interfering interactions of EDTA with lipids and other biomolecules involved in the experiment, e.g., cationic peptides, that may alter membrane-binding affinities of studied compounds.
Topics: Phosphatidylcholines; Edetic Acid; Membranes, Artificial; Molecular Dynamics Simulation; Ions
PubMed: 37307026
DOI: 10.1021/acs.jpcb.3c03207 -
The Journal of Biological Chemistry Feb 2012Phosphatidylcholine (PC) is the most abundant component of lipid bilayers and exists in various molecular forms, through combinations of two acylated fatty acids....
Phosphatidylcholine (PC) is the most abundant component of lipid bilayers and exists in various molecular forms, through combinations of two acylated fatty acids. Arachidonic acid (AA)-containing PC (AA-PC) can be a source of AA, which is a crucial mediator of synaptic transmission and intracellular signaling. However, the distribution of AA-PC within neurons has not been indicated. In the present study, we used imaging mass spectrometry to characterize the distribution of PC species in cultured neurons of superior cervical ganglia. Intriguingly, PC species exhibited a unique distribution that was dependent on the acyl chains at the sn-2 position. In particular, we found that AA-PC is enriched within the axon and is distributed across a proximal-to-distal gradient. Inhibitors of actin dynamics (cytochalasin D and phallacidin) disrupted this gradient. This is the first report of the gradual distribution of AA-PC along the axon and its association with actin dynamics.
Topics: Actins; Animals; Arachidonic Acid; Axons; Biological Transport; Mice; Models, Molecular; Molecular Conformation; Phosphatidylcholines; Superior Cervical Ganglion
PubMed: 22207757
DOI: 10.1074/jbc.M111.316877 -
The Journal of Membrane Biology Aug 2015Monolayers of phosphatidylcholine (PC), tetradecanol (TD), hexadecanol (HD), octadecanol (OD) and eicosanol (E) and their binary mixtures were investigated at the...
Monolayers of phosphatidylcholine (PC), tetradecanol (TD), hexadecanol (HD), octadecanol (OD) and eicosanol (E) and their binary mixtures were investigated at the air/water interface. The surface tension values of pure and mixed monolayers were used to calculate π-A isotherms. The surface tension measurements were carried out at 22 °C using a Teflon trough and a Nima 9000 tensiometer. The interactions between phosphatidylcholine and fatty alcohols (tetradecanol, hexadecanol, octadecanol, eicosanol) result in significant deviations from the additivity rule. An equilibrium theory to describe the behavior of monolayer components at the air/water interface was developed in order to obtain the stability constants, Gibbs free energy values and areas occupied by one molecules of PC-TD, PC-HD, PC-OD and PC-E complexes. We considered the equilibrium between the individual components and the complex and established that phosphatidylcholine and fatty alcohols formed highly stable 1:1 complexes.
Topics: Fatty Alcohols; Phase Transition; Phosphatidylcholines; Unilamellar Liposomes
PubMed: 25801604
DOI: 10.1007/s00232-015-9793-x -
Biochimica Et Biophysica Acta Sep 1996A recently discovered submain phase transition in multi-lamellar bilayers of long-chain saturated diacyl phosphatidylcholines (Jørgensen, K. (1995) Biochim. Biophys.... (Comparative Study)
Comparative Study Review
A recently discovered submain phase transition in multi-lamellar bilayers of long-chain saturated diacyl phosphatidylcholines (Jørgensen, K. (1995) Biochim. Biophys. Acta 1240, 111-114) is discussed in terms of a theoretical molecular interaction model using computer simulation techniques. The model interprets the transition to be due to a decoupling of the acyl-chain melting from the melting of the pseudo-two-dimensional crystalline lattice of the P beta' phase. A two-stage melting process is predicted by the calculations suggesting that the sub-main transition involves a lattice melting whereas the acyl-chain melting takes place at a higher temperature at the main transition. The calculated heat contents of the two transitions as well as the chain-length dependence compare favorably with experimental data for multi-lamellar phosphatidylcholine lipid bilayers.
Topics: Calorimetry; Chemical Phenomena; Chemistry, Physical; Computer Simulation; Lipid Bilayers; Models, Molecular; Phosphatidylcholines; Phospholipids; Thermodynamics
PubMed: 8809096
DOI: 10.1016/0005-2736(96)00086-7 -
Scientific Reports Feb 2016Choline is an essential nutrient for all living cells and is produced extracellularly by sequential degradation of phosphatidylcholine (PC). However, little is known...
Choline is an essential nutrient for all living cells and is produced extracellularly by sequential degradation of phosphatidylcholine (PC). However, little is known about how choline is produced extracellularly. Here, we report that ENPP6, a choline-specific phosphodiesterase, hydrolyzes glycerophosphocholine (GPC), a degradation product of PC, as a physiological substrate and participates in choline metabolism. ENPP6 is highly expressed in liver sinusoidal endothelial cells and developing oligodendrocytes, which actively incorporate choline and synthesize PC. ENPP6-deficient mice exhibited fatty liver and hypomyelination, well known choline-deficient phenotypes. The choline moiety of GPC was incorporated into PC in an ENPP6-dependent manner both in vivo and in vitro. The crystal structure of ENPP6 in complex with phosphocholine revealed that the choline moiety of the phosphocholine is recognized by a choline-binding pocket formed by conserved aromatic and acidic residues. The present study provides the molecular basis for ENPP6-mediated choline metabolism at atomic, cellular and tissue levels.
Topics: Animals; Crystallography, X-Ray; Endothelial Cells; Fatty Liver; Liver; Mice; Mice, Knockout; Oligodendroglia; Organ Specificity; Phosphatidylcholines; Phosphoric Diester Hydrolases; Structure-Activity Relationship; Substrate Specificity
PubMed: 26888014
DOI: 10.1038/srep20995 -
Journal of Applied Physiology... May 2007Monomolecular films of phospholipids in the liquid-expanded (LE) phase after supercompression to high surface pressures (pi), well above the equilibrium surface pressure...
Monomolecular films of phospholipids in the liquid-expanded (LE) phase after supercompression to high surface pressures (pi), well above the equilibrium surface pressure (pi(e)) at which fluid films collapse from the interface to form a three-dimensional bulk phase, and in the tilted-condensed (TC) phase both replicate the resistance to collapse that is characteristic of alveolar films in the lungs. To provide the basis for determining which film is present in the alveolus, we measured the melting characteristics of monolayers containing TC dipalmitoyl phosphatidylcholine (DPPC), as well as supercompressed 1-palmitoyl-2-oleoyl phosphatidylcholine and calf lung surfactant extract (CLSE). Films generated by appropriate manipulations on a captive bubble were heated from < or =27 degrees C to > or =60 degrees C at different constant pi above pi(e). DPPC showed the abrupt expansion expected for the TC-LE phase transition, followed by the contraction produced by collapse. Supercompressed CLSE showed no evidence of the TC-LE expansion, arguing that supercompression did not simply convert the mixed lipid film to TC DPPC. For both DPPC and CLSE, the melting point, taken as the temperature at which collapse began, increased at higher pi, in contrast to 1-palmitoyl-2-oleoyl phosphatidylcholine, for which higher pi produced collapse at lower temperatures. For pi between 50 and 65 mN/m, DPPC melted at 48-55 degrees C, well above the main transition for bilayers at 41 degrees C. At each pi, CLSE melted at temperatures >10 degrees C lower. The distinct melting points for TC DPPC and supercompressed CLSE provide the basis by which the nature of the alveolar film might be determined from the temperature-dependence of pulmonary mechanics.
Topics: 1,2-Dipalmitoylphosphatidylcholine; Animals; Biological Products; Biomechanical Phenomena; Cattle; Elasticity; Hydrostatic Pressure; Microbubbles; Models, Biological; Molecular Conformation; Phase Transition; Phosphatidylcholines; Pulmonary Alveoli; Pulmonary Surfactants; Respiratory Mechanics; Surface Properties; Time Factors; Transition Temperature
PubMed: 17194731
DOI: 10.1152/japplphysiol.00948.2006