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Chemistry & Biodiversity Jun 2016The positional-species composition (PSC) of 3-acetyl-1,2-diacyl-sn-glycerols (AcDAGs) from the seeds of mature fruits of 14 species of the genus Euonymus L. was...
The positional-species composition (PSC) of 3-acetyl-1,2-diacyl-sn-glycerols (AcDAGs) from the seeds of mature fruits of 14 species of the genus Euonymus L. was established. The residues of six major fatty acids (FAs), palmitic (P), stearic (St), hexadecenoic (H), octadecenoic (O), linoleic (L), and linolenic (Ln), were present in the AcDAGs. Here, we demonstrated that the profile of PSC of AcDAGs could serve as chemotaxonomic factor to divide euonymus species studied here into groups which completely correlate with the present day systematic of the genus. In particular, the Euonymus section greatly exceeded other sections of the Euonymus subgenus as well as the Kalonymus one in the total levels of AcDAGs positional species having one and two O residues and was characterized by significantly lesser concentrations of species with one and two L residues. Moreover, in seed, AcDAGs of almost all Euonymus species EFL values were slightly higher than EFO ones, but all EFL and EFO values were higher than 1.0, and therefore, it can be concluded that both FAs mainly esterified sn-2-position of the glycerol moiety and saturated FAs residues were always virtually absent in the sn-2 position of Euonymus seed AcDAGs, as it is also the case in nearly all TAGs molecules of plant origin.
Topics: Acetates; Diglycerides; Euonymus; Fruit; Seeds
PubMed: 27151557
DOI: 10.1002/cbdv.201500269 -
Methods in Molecular Biology (Clifton,... 1998
Review
Topics: Diglycerides; Humans; Monoacylglycerol Lipases
PubMed: 10427560
DOI: 10.1385/0-89603-491-7:167 -
Biochemistry Dec 2007The alpha, zeta, and epsilon isoforms of diacylglycerol kinase exhibit a high degree of stereospecificity in the phosphorylation of diacylglycerol. In comparison, a...
The alpha, zeta, and epsilon isoforms of diacylglycerol kinase exhibit a high degree of stereospecificity in the phosphorylation of diacylglycerol. In comparison, a multiple lipid kinase, MuLK, shows much less stereospecificity, phosphorylating 1,2-dioleoylglycerol only approximately 2-3 times more rapidly than 2,3-dioleoylglycerol. The alpha and zeta isoforms of diacylglycerol kinase are inhibited by 2,3-dioleoylglycerol, but not the more substrate-selective epsilon isoform. The inhibition by 2,3-dioleoylglycerol is uncompetitive. This corresponds to a kinetic scheme in which the inhibitor can bind to the enzyme-substrate complex, but not to the free enzyme. Our data indicate that despite their similar structures, 1,2-dioleoylglycerol and 2,3-dioleoylglycerol do not compete for the active site of these three isoforms of diacylglycerol kinase. We suggest that the 2,3-dioleoylglycerol binds to a site on the alpha and zeta isoforms of diacylglycerol kinase that is exposed as a consequence of the substrate binding to the active site. The chiral specificity of these enzymes thus mimics the substrate specificity, with MuLK being the least selective and the epsilon isoform of diacylglycerol kinase exhibiting the greatest selectivity.
Topics: Binding Sites; Diacylglycerol Kinase; Diglycerides; Humans; Kinetics; Lipoprotein Lipase; Phosphotransferases (Alcohol Group Acceptor); Stereoisomerism; Substrate Specificity
PubMed: 18004883
DOI: 10.1021/bi701584v -
International Journal of Molecular... Nov 2022The C-type natriuretic peptide receptor (NPRC) is expressed in many cell types and binds all natriuretic peptides with high affinity. Ligand binding results in the...
C Type Natriuretic Peptide Receptor Activation Inhibits Sodium Channel Activity in Human Aortic Endothelial Cells by Activating the Diacylglycerol-Protein Kinase C Pathway.
The C-type natriuretic peptide receptor (NPRC) is expressed in many cell types and binds all natriuretic peptides with high affinity. Ligand binding results in the activation or inhibition of various intracellular signaling pathways. Although NPRC ligand binding has been shown to regulate various ion channels, the regulation of endothelial sodium channel (EnNaC) activity by NPRC activation has not been studied. The objective of this study was to investigate mechanisms of EnNaC regulation associated with NPRC activation in human aortic endothelial cells (hAoEC). EnNaC protein expression and activity was attenuated after treating hAoEC with the NPRC agonist cANF compared to vehicle, as demonstrated by Western blotting and patch clamping studies, respectively. NPRC knockdown studies using siRNA's corroborated the specificity of EnNaC regulation by NPRC activation mediated by ligand binding. The concentration of multiple diacylglycerols (DAG) and the activity of protein kinase C (PKC) was augmented after treating hAoEC with cANF compared to vehicle, suggesting EnNaC activity is down-regulated upon NPRC ligand binding in a DAG-PKC dependent manner. The reciprocal cross-talk between NPRC activation and EnNaC inhibition represents a feedback mechanism that presumably is involved in the regulation of endothelial function and aortic stiffness.
Topics: Humans; Endothelial Cells; Protein Kinase C; Natriuretic Peptide, C-Type; Diglycerides; Ligands; Natriuretic Peptides
PubMed: 36430437
DOI: 10.3390/ijms232213959 -
Nature Communications Jul 2019Studies on vesicle formation by the Coat Protein I (COPI) complex have contributed to a basic understanding of how vesicular transport is initiated. Phosphatidic acid...
Studies on vesicle formation by the Coat Protein I (COPI) complex have contributed to a basic understanding of how vesicular transport is initiated. Phosphatidic acid (PA) and diacylglycerol (DAG) have been found previously to be required for the fission stage of COPI vesicle formation. Here, we find that PA with varying lipid geometry can all promote early fission, but only PA with shortened acyl chains promotes late fission. Moreover, diacylglycerol (DAG) acts after PA in late fission, with this role of DAG also requiring shorter acyl chains. Further highlighting the importance of the short-chain lipid geometry for late fission, we find that shorter forms of PA and DAG promote the vesiculation ability of COPI fission factors. These findings advance a general understanding of how lipid geometry contributes to membrane deformation for vesicle fission, and also how proteins and lipids coordinate their actions in driving this process.
Topics: COP-Coated Vesicles; Coat Protein Complex I; Diglycerides; Golgi Apparatus; HeLa Cells; Humans; Phosphatidic Acids
PubMed: 31363100
DOI: 10.1038/s41467-019-11324-4 -
Biophysical Journal Apr 2015Diacylglycerol (DAG)-induced activation of phosphatidylinositol-phospholipase C (PI-PLC) was studied with vesicles containing PI, either pure or in mixtures with...
Diacylglycerol (DAG)-induced activation of phosphatidylinositol-phospholipase C (PI-PLC) was studied with vesicles containing PI, either pure or in mixtures with dimyristoyl phosphatidylcholine, distearoyl phosphatidylcholine, sphingomyelin, or galactosylceramide, used as substrates. At 22°C, DAG at 33 mol % increased PI-PLC activity in all of the mixtures, but not in pure PI bilayers. DAG also caused an overall decrease in diphenylhexatriene fluorescence polarization (decreased molecular order) in all samples, and increased overall enzyme binding. Confocal fluorescence microscopy of giant unilamellar vesicles of all of the compositions under study, with or without DAG, and quantitative evaluation of the phase behavior using Laurdan generalized polarization, and of enzyme binding to the various domains, indicated that DAG activates PI-PLC whenever it can generate fluid domains to which the enzyme can bind with high affinity. In the specific case of PI/dimyristoyl phosphatidylcholine bilayers at 22°C, DAG induced/increased enzyme binding and activation, but no microscopic domain separation was observed. The presence of DAG-generated nanodomains, or of DAG-induced lipid packing defects, is proposed instead for this system. In PI/galactosylceramide mixtures, DAG may exert its activation role through the generation of small vesicles, which PI-PLC is known to degrade at higher rates. In general, our results indicate that global measurements obtained using fluorescent probes in vesicle suspensions in a cuvette are not sufficient to elucidate DAG effects that take place at the domain level. The above data reinforce the idea that DAG functions as an important physical agent in regulating membrane and cell properties.
Topics: Diglycerides; Phosphoinositide Phospholipase C; Unilamellar Liposomes
PubMed: 25863059
DOI: 10.1016/j.bpj.2015.02.020 -
Biochimica Et Biophysica Acta Mar 1994The interaction of 1,2-dipalmitoylglycerol (1,2-DPG) with dipalmitoylphosphatidylserine (DPPS) has been studied in the presence and in the absence of Ca2+ by using...
The interaction of 1,2-dipalmitoylglycerol (1,2-DPG) with dipalmitoylphosphatidylserine (DPPS) has been studied in the presence and in the absence of Ca2+ by using differential scanning calorimetry (DSC) and 31P-nuclear magnetic resonance (31P-NMR). In the absence of Ca2+, DSC showed that 1,2-DPG increased the phase transition of DPPS, effect already noticed at very low 1,2-DPG concentrations, whereas lipid immiscibilities were detected at concentrations of 1,2-DPG higher than about 30 mol%. 31P-NMR indicated that lamellar phases were always present at concentration of 1,2-DPG lower than about 35 mol%, but at higher concentrations non-lamellar phases may be present in the fluid phase. As observed by DSC, the apparent pKa of the carboxyl group of DPPS was increased slightly in the presence of 1,2-DPG. In the presence of Ca2+, the effect of 1,2-DPG was to further increase the temperature of the onset of the phase transition, indicating an stabilization of the most rigid phase in the DPPS/1,2-DPG/Ca2+ samples. Even concentrations of 1,2-DPG as low as 1 mol% of the total lipid already produced a noticeable effect. Moreover, lipid immiscibilities were apparent at concentrations of 1,2-DPG higher than 20 mol%. Furthermore, the transition of the DPPS/Ca2+ complex observed by DSC at 155 degrees C was perturbed by the presence of 1,2-DPG, indicating a change in the structure of the crystalline complex. Interestingly, the effect of non-saturating Ca2+ concentrations on the DPPS phase transition was enhanced by the presence of 1,2-DPG. The effect reported here may be significant for a number of situations where Ca2+, phosphatidylserine and diacylglycerols are involved, such as fusion of membranes, where diacylglycerol may facilitate Ca(2+)-induced fusion, or the activation of enzymes such as protein kinase C and phospholipases.
Topics: Calcium; Calorimetry, Differential Scanning; Diglycerides; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Phosphatidylserines; Temperature
PubMed: 8142425
DOI: 10.1016/0005-2736(94)90083-3 -
The Journal of Nutrition Jul 2006Studies have shown several beneficial effects of dietary diacylglycerol oil (DAG oil), but the mechanism behind these effects is still not clear. One hypothesis is that...
Studies have shown several beneficial effects of dietary diacylglycerol oil (DAG oil), but the mechanism behind these effects is still not clear. One hypothesis is that an increase in portal vein transport of nonesterified fatty acids (NEFA) with subsequent oxidation in the liver might be responsible for the positive effects. We examined the portal vein transport of NEFA and other lipid related variables, in response to DAG and triacylglycerol (TAG) bolus feeding and a bolus of standard pig feed in 4 portal vein and mesenteric artery catheterized pigs. Also, the effect of the boluses on postprandial lipid variables was examined. Portal vein transport of NEFA did not differ when pigs were administered the 2 oil bolus diets, consistent with the similar portal plasma concentrations of oleic and linolenic acids during h 1 after feeding. Glycerol, on the contrary, was transported by the portal vein to a much higher degree after intake of DAG oil (P < 0.001; 20, 40, and 60 min). The postprandial arterial TAG response at 5 and 6 h postprandially was significantly lower after the DAG bolus intake. Analysis of Delta AUC for the 6-h postprandial period of selected and total fatty acids showed a lower concentration of vaccenic acid (P = 0.002) after the DAG bolus diet. In conclusion, DAG bolus feeding did not increase the portal transport of NEFA, but it did increase the portal transport of glycerol and lower the postprandial lipid concentration in arterial plasma.
Topics: Absorption; Animals; Area Under Curve; Biological Transport; Dietary Fats, Unsaturated; Diglycerides; Fatty Acids, Nonesterified; Female; Portal Vein; Postprandial Period; Swine; Triglycerides
PubMed: 16772440
DOI: 10.1093/jn/136.7.1800 -
Food Chemistry Oct 2013An experimental investigation was carried out with the aim to investigate on the isomerisation of 1,2-diacylglycerols to 1,3-diacylglycerols as a function of the storage...
An experimental investigation was carried out with the aim to investigate on the isomerisation of 1,2-diacylglycerols to 1,3-diacylglycerols as a function of the storage conditions, as well as to identify indices useful to evaluate the freshness of the oils. Two oils derived from two different cultivars (Coratina and Ogliarola barese) were stored for two years as follows: in bottles at dark; in clear glass bottles at light; in green glass bottles at light; in bottles at dark, the latter subjected to repeated opening and samplings to simulate domestic use. The obtained results evinced that during the storage period a significant increase in the 1,3-isomers was observed due to an isomerisation from the 1,2 to the 1,3 isomeric form, consequently the 1,3/1,2 ratio increased in both oils. The covariance analysis of the data showed that the isomerisation of diacylglycerols, taking place during time, was affected by the type of oil, probably due to the different initial hydrolysis level, but was not affected by the storage conditions. Among the parameters considered, the total diacylglycerols/1,3-diacylglycerols ratio could be used as freshness index of extra virgin olive oil, since it is not affected by either oil or storage conditions.
Topics: Diglycerides; Food Storage; Isomerism; Olive Oil; Plant Oils; Quality Control
PubMed: 23692765
DOI: 10.1016/j.foodchem.2012.10.120 -
The Journal of Biological Chemistry Jan 1983When platelets are stimulated by thrombin, a phosphatidylinositol-specific phospholipase C produces a transient rise in 1,2-diacylglycerol. We have now characterized the...
When platelets are stimulated by thrombin, a phosphatidylinositol-specific phospholipase C produces a transient rise in 1,2-diacylglycerol. We have now characterized the hydrolysis of diacylglycerol by platelet membranes using doubly isotopically labeled substrates of defined fatty acid composition. We find that the fatty acid at sn-1 is hydrolyzed faster than that at sn-2 thereby producing a 2-monoacylglycerol intermediate. If hydrolysis had occurred at either position randomly, 1-monoacylglycerol would also be produced. That none was detected indicates that either the sn-1 fatty acid must be cleaved first or that 1-monoacylglycerol is hydrolyzed by monoacylglycerol lipase much faster than 2-monoacylglyceol. The latter possibility was excluded by the finding that 1-monoacylglycerol and 2-monoacylglycerol are hydrolyzed at equal rates by platelet membranes. The diacylglycerol lipase cleaves diacylglycerols with sn-1 palmitate as rapidly as those with sn-1 stearate. Arachidonate at sn-2 is cleaved twice as fast as sn-2 oleate by monoacylglycerol lipase. The two activities probably represent discrete enzymes since monoacylglycerol lipase activity can be separated from diacylglycerol lipase by fractionation on DEAE-Sepharose, although both are contained in the membrane fraction of platelets. That the sequential breakdown of 1,2-diacylglycerol also occurs in intact platelets is indicated by our finding of a transient rise in arachidonoyl-monoacylglycerol in thrombin-stimulated platelets. This provides further evidence for a role of the phospholipase C-diacylglycerol lipase pathway in the release of arachidonic acid.
Topics: Blood Platelets; Chromatography, Ion Exchange; Diglycerides; Fatty Acids; Glycerides; Humans; Hydrolysis; Lipase; Thrombin; Time Factors
PubMed: 6822511
DOI: No ID Found