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At least 19 recordsLinked to original sources
PubMed1994

Glyceryl-ether monooxygenase (EC 1.14.16.5): nature of the glyceryl-ether lipid substrates in aqueous buffer.

The kinetics of inhibition of glyceryl-ether monooxygenase with 6-methyl-5,6,7,8-tetrahydropterin as cofactor (saturating) by the detergent Mega-10 with batyl alcohol and (RS)-3-(1-hexadecyloxy)-2-hydroxypropane-1-phosphocholine as substrates exhibited noncompetitive inhibition with apparent Ki values of 1.74 +/- 0.37 mM and 185 +/- 23 microM, respectively. Inhibition by octadecan-1-ol (with batyl alcohol as substrate in the presence of 2.3 mM Mega-10) was competitive with an apparent Ki value of 765 +/- 80 microM. The critical micelle concentration values of various solutions of Mega-10 were determined and used to show that the active ether-lipid substrates were in micelle form (for a water soluble substrate) or mixed micelle form (for substrates solubilised with Mega-10).

Animals↗
PubMed1981

Contraction of guinea pig ileal smooth muscle by acetyl glyceryl ether phosphorylcholine.

Acetyl glyceryl ether phosphorylcholine (AGEPC) is a chemical that has the biological activity of what was formerly termed platelet-activating factor. We report here that synthetic AGEPC induces the contraction of guinea pig ileal smooth muscle. Antagonists of histamine, acetylcholine, and slow-reacting substances (SRS) do not block AGEPC-induced contraction. These responses were long lasting, resistant to washing, and displayed complete agonist specific desensitization. Histamine- and SRS-induced contractions were unaffected by AGEPC. These studies show that AGEPC has the potential to produce a component of anaphylactically induced smooth muscle contraction.

Animals↗
PubMed1981

Human platelet stimulation by acetyl glyceryl ether phosphorylcholine.

Acetyl glyceryl ether phosphorylcholine (AGEPC) induced dose-dependent platelet aggregation and release of [3H]serotonin and platelet factor 4 in citrated human platelet-rich plasma. ADP scavengers or indomethacin prevented irreversible platelet aggregation responses induced by 0.2 microM AGEPC but had no effect upon platelet secretion; prostacyclin inhibited AGEPC-induced aggregation and secretion. EDTA or EGTA inhibited AGEPC-induced aggregation but had no effect on platelet secretion.

Blood Coagulation Factors↗
PubMed1987

The glyceryl ethers of Paramecium phospholipids and phosphonolipids.

Two glyceryl ethers, 1-O-hexadecyl glycerol and 1-O-cis-octadec-11-enyl glycerol, chimyl and paramecyl alcohol, respectively, were quantified in total phospholipids and five glycerophospholipid classes from cells and cilia of the ciliated protozoon, Paramecium tetraurelia. The ether content of 2-aminoethyl phosphonoglycerolipid was 85-90 mole %. Concentrations of ethers were greatest in the ethanolamine phosphonolipids greater than phosphatidylcholines greater than phosphatidylserines greater than phosphatidylethanolamines greater than phosphatidylinositols. The glyceryl ether concentrations in total cellular phospholipids increased with culture age in P. tetraurelia and P. multimicronucleatum cells. The glyceryl ether concentrations in the phospholipids of P. tetraurelia cilia remained constant from mid log to stationary phase of culture growth. Paramecium tetraurelia phospholipid glyceryl ether concentrations were made greater by supplementation of cultures with chimyl alcohol.

Animals↗
PubMed1982

Increasing the levels of ether-linked lipids in L-M cells by glyceryl ether supplementation depresses growth and choline utilization.

To gain insight into the role of alkyl-linked lipids in biological systems, we added hexadecylglycerol (a precursor of complex ether-linked lipids) to medium required for the growth of L-M cells in culture. L-M fibroblasts cultured through several generations in the presence of hexadecylglycerol grow at a reduced rate. Experimental cells at their sixth passage, with 2 microgram supplement/ml, double at 50% the rate of control cell populations. Hexadecylglycerol (10 microgram/ml) added 1 day after cell passage does not retard growth; however, within 1 h it decreases the incorporation of choline into the choline glycerophosphatide fraction. Inhibition is specific for choline; ethanolamine incorporation is not affected. The inhibition of choline utilization by hexadecylglycerol-treated cells is dose-dependent and reaches a maximum 12 h after supplementation. Cellular uptake of choline is reduced (approx. 17%) but not as much as the incorporation of choline into the phospholipids (approx. 60% at 12 h). The assimilation of ether lipid precursor into cellular phospholipids was followed by incubating cells with [1-14C]hexadecylglycerol. Incorporation of radioactivity into cellular phospholipids begins to plateau after 24 h, whereas the interference of hexadecylglycerol with choline metabolism could be detected as early as 1 h. The majority of the radioactivity recovered from cells incubated with labeled hexadecylglycerol is localized in the microsomal fraction (56%), where the label was distributed as free hexadecyglycerol, alkylacyl-phospholipids and alkyldiacylglycerols. These results show that the supplementation of a glyceryl ether to L-M fibroblast growth media selectively inhibits the utilization of choline for choline glycerophospholipid biosynthesis and causes a reduction in cell growth rate when cells are continually passaged in the presence of the glyceryl ether.

Choline↗
PubMed1998

Glyceryl-ether monooxygenase [EC 1.14.16.5]. A microsomal enzyme of ether lipid metabolism.

The history, biological, and medical aspects of glyceryl ethers, as well as their chemical syntheses, biosynthesis, and their chemical and physical properties are briefly reviewed as background information for appreciating the importance of the enzyme glyceryl-ether monooxygenase, and for embarking on new studies of this enzyme. The occurrence, isolation and general properties of the microsomal, membrane-bound, glyceryl-ether monooxygenase from rat liver are described. Radiometric, nonradiometric, and coupled and direct spectrophotometric assays for this enzyme are detailed. The effects of detergents on the kinetics of this enzyme are described together with the stoichiometry and the effects of inhibitors. The structure-activity relationships of pterin cofactors and of ether lipid substrates, including their stereospecificities, have been summarized from enzyme kinetic data which are also tabulated. The mechanism of enzymic hydroxylation of glyceryl ethers and a model for the active site of glyceryl-ether monooxygenase are proposed from these apparent kinetic data. Notes on useful future studies of this monooxygenase have been made.

Animals↗
PubMed1984

Acetyl glyceryl ether phosphorylcholine (AGEPC). A putative mediator of cardiac anaphylaxis in the guinea pig.

Platelet-activating factor is a novel phospholipid that has been implicated as an important mediator of acute allergic reactions. The intravenous administration of acetyl glyceryl ether phosphorylcholine, a pure, synthetic platelet-activating factor, causes electrocardiographic changes in the rabbit similar to those which are characteristic manifestations of systemic anaphylaxis. To determine whether platelet-activating factor contributes to anaphylactic cardiac dysfunction, we measured platelet-activating factor release from the sensitized guinea pig heart challenged in vitro with specific antigen and compared the resulting cardiac dysfunction with that induced by the injection of acetyl glyceryl ether phosphorylcholine into nonsensitized hearts. The results of these studies document that, during anaphylaxis in the isolated guinea pig heart, a platelet-activating factor is released into the coronary effluent that has physicochemical and functional properties similar to those of acetyl glyceryl ether phosphorylcholine. The intracardiac administration of acetyl glyceryl ether phosphorylcholine (10(-14) to 3 X 10(-9) mol) induced dose-related decreases in left ventricular contractile force (-5 to -85%) and coronary flow (-5 to -85%), as well as impaired atrioventricular conduction. The negative inotropic effect of acetyl glyceryl ether phosphorylcholine also was present in hearts perfused at constant flow. Although, in these hearts, acetyl glyceryl ether phosphorylcholine increased coronary resistance, which may have caused regional shunting and ischemia, it is unlikely that the negative inotropic effect of acetyl glyceryl ether phosphorylcholine was secondary to changes in coronary flow, since acetyl glyceryl ether phosphorylcholine also caused a dose-dependent negative inotropic effect in the electrically paced, noncoronary-perfused left atrium and right ventricular papillary muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylaxis↗
PubMed1998

Characterizations of Pneumocystis carinii and rat lung lipids: glyceryl ethers and fatty alcohols.

Pneumocystis carinii carinii and rat lung phospholipids contained 3-6% 1-alkyl-2-acyl glycerols composed of the glyceryl ether species, 1-O-octadecyl glycerol (batyl alcohol), 1-O-octadec-9-enyl glycerol (selachyl alcohol), 1-O-hexadecyl glycerol (chimyl alcohol), and 1-O-hexadec-9-enyl glycerol. Of the major phospholipid classes, phosphatidylinositol (PI) and phosphatidylserine contained the highest percentage of alkyl acyl glycerols. Methylprednisolone treatment caused an increase in alkyl acyl PI of rat lung lipids from 12% to 45%. As the PI concentration in lung phospholipids increases in rats treated with methylprednisolone, the increase in alkyl acyl PI was substantial; the proportions of alkyl acyl phosphatidylethanolamine and alkyl acyl lyso phosphatidylcholine (PC) also increased. Pneumocystis phospholipids contained higher proportions of alkyl acyl PC than the phospholipids of the lungs from normal and immunosuppressed uninfected rats. The glyceryl ether compositions of P. carinii carinii PC and lyso PC were similar, which suggests that lyso PC in the organism is derived by phospholipase A2 action on PC. This was not the case for PC and lyso PC of the lung controls. Analysis of the free fatty alcohols, precursors of glyceryl ethers identified only saturated species in P. carinii carinii and rat lung controls. Thus, the introduction of a double bond in the alcohol moiety of glyceryl ethers occurs after formation of the ether linkage between fatty alcohol and the glyceryl backbone.

Animals↗
PubMed1975

Chromatographic analysis of the neutral and phosphatide glyceryl ethers from various biological sources.

A method of analysis is described which permits the facile evaluation of the neutral glyceryl ether lipids (mild alkaline hydrolysis) and total glyceryl ether lipid (Vitride reduction) thereby allowing an assessment of the phosphatide contribution. The alkyl and alk-enyl glyceryl ethers are chromatographically resolvable on Gelman glass-fiber type SG and Whatman SG-81 and detected by the periodic acid-Schiff and plasmal reaction, respectively. The attending problems and interpretation are discussed with examples from a number of unicellular organisms and animal tissues.

Amphibians↗
PubMed1991

Glyceryl ethers in peroxisomal disease.

1-O-Alkyl and 1-O-alk-1-enyl (plasmalogens) glyceryl ether lipid levels were measured in post-mortem brain and/or liver biopsies from 7 patients with ultrastructural and biochemical evidence of a defect in peroxisomal biogenesis and/or enzymological evidence of a disturbance in ether lipid synthesis. Near normal levels of both species of glyceryl ether lipids were found in neonatal adrenoleukodystrophy and infantile Refsum's disease but marked deficiencies were found in Zellweger's syndrome and rhizomelic chondrodysplasia punctata, the latter manifesting the most profound reduction in ether lipid levels. These observations suggest that little ether lipid biosynthesis occurs in vivo in rhizomelic chondrodysplasia punctata or Zellweger's syndrome. However, in some phenotypes with apparently gross reductions in peroxisomal numbers, e.g. neonatal adrenoleukodystrophy and infantile Refsom's disease, there is significant ether lipid synthesis in liver and brain.

Adrenoleukodystrophy↗
PubMed1978

Distinctive medium chain wax esters, triglycerides, and diacyl glyceryl ethers in the head fats of the Pacific beaked whale, Berardius bairdi.

Lipids were extracted from the mandibular fat body (jaw), the fatty forehead (melon), and the dorsal blubber of a Pacific beaked whale (Berardius bairdi) and separated into lipid classes by preparative thin layer chromatogrphy. The head fats were mixtures of wax esters and triglycerides with a very small amount of diacyl glyceryl ether. The blubber fat contained 97% wax ester and 3% triglyceride. Gas liquid chromatography (GLC) of the intac lipid classes indicated an unusually low C26-C30 range for most of the jaw and melon wax esters compared to the more normal C32-C40 molecules found in the blubber. Distinctive lower molecular weight C24-C40 triglycerides occurred in the head fats vs. the usual C44-C58 range in the blubber. Most diacyl glyceryl ethers were in the C35-C46 range, below the molecular weight of hexadecyldipalmitoyl glyceryl ether (C48). GLC of the derived fatty acid methyl esters showed that the lower molecular weight neutral lipids in the head fats were due to high levels of iso-10:0, n-10:0, iso-11:0, iso-12:0, N-12:0, and iso-13:0 acids. The wax ester fatty alcohols and the alkoxy chains of the glyceryl ethers were mostly the C14-C20 chain lengths commonly observed in marine organisms. The distinctive medium chain neutral lipids in the jaw and melon fats of this whale may be related to the postulated acoustical role of these tissues in echolocation.

Adipose Tissue↗
PubMed2001

Identification and quantification of molecular species of diacyl glyceryl ether by reversed-phase high-performance liquid chromatography with refractive index detection and mass spectrometry.

We have developed a method to identify and quantify the molecular species of diacyl glyceryl ether (DAGE) using high-performance liquid chromatography (HPLC) equipped with a refractive index detector and an electrospray ionization and time of flight mass spectrometer (LC-RI-MS). An octadecyl silica column with a mixture of acetonitrile and dichloromethane (65:35, v/v) as an eluant was used for the HPLC. When the LC-RI-MS method was applied to a mixture of synthetic DAGEs; 1-O-hexadecyl-2,3-dioleoylglycerol (O-16:0-18:1-18:18:1), 1-O-octadecyl-2,3-dioleoylglycerol (O-18:0-18:1-18:1), 1-O-octadecenyl-2,3-dioleoylglycerol (O-18:1-18:1-18:1), 1-O-octadecyl-2,3-didocodahexaenoylglycerol (O-18:0-22:6-22:6), and 1-O-octadecenyl-2,3-didocosahexaenoylglycerol (O-18:1-22:6-22:6), good separation and quantification were obtained on the refractive index chromatogram. A pseudo-molecular ion [M+NH4]+ and a monoacyl glyceryl ether ion [M-RCO2] + were observed for all synthetic DAGEs on the mass spectrum. It was found that the fatty acids and glyceryl ether in DAGE could be easily identified by these mass spectra. When this LC-RI-MS method was applied to the DAGEs extracted from muscle of Stromateus stellatus, approximately 18 peaks were observed on LC-RI-MS chromatograms and the major molecular species of DAGEs were identified as O-16:0-18:1-18:1.

Animals↗