Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PALMITIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed1996

Affinity of fatty acid for (r)rat intestinal fatty acid binding protein:further examination.

The enhancement of the fluorescence quantum yield of 1,8-anilinonaphthalenesulfonic acid (ANS) upon binding to intestinal fatty acid protein (I-FABP) was exploited to devise an assay for free I-FABP. With this assay, we monitored the competition for free I-FABP between ANS and fatty acids and thereby extracted values for the dissociation constants (K(FA)) of fatty acids for I-FABP. We obtained these constants for the I-FABP ligands oleic acid, arachidonic acid, and palmitic acid. In addition, we measured the dependence of K(FA) for oleic acid upon temperature and at two pH values. From these data, we calculate the van't Hoff enthalpy of oleic acid binding. This enthalpy is compared with the enthalpies of binding obtained directly from titration calorimetry. Our experiments with the fluorescence-based assay generate values of K(FA) which disagree with older values obtained from calorimetry and other methods. Our own calorimetric data were analyzed with a view to improving the technique involved in subtraction of a "reference" dilution of the ligand into solution in the absence of the protein. By this maneuver, we obtained "corrected" titrations which could be fitted to values of K(FA) more in agreement with the values we determined via the fluorescence-based assay than wer the older literature values. Our new values for K(FA) also agree substantially with values derived using a complementary assay technique, one measuring the concentration of free fatty acid, that has recently been developed by Richiere et al [Richiere et al. (1995) J. Biol. Chem. 270, 15076-15084]. We compare the values of delta H degrees, delta S degrees, and delta C(p)degrees for fatty acid binding we have obtained in this work with those we found in earlier work with ANS binding to I-FABP [Kirk et al. (1996) Biophys. J. 70, 69-83]. Our interpretation of the origin of the thermodynamic changes for ANS binding in our earlier work is here substantiated and extended to include an evaluation in physical terms of the interaction of I-FABP with fatty acids.

Anilino Naphthalenesulfonates↗
PubMed1965

LIPIDS OF ISOLATED NEURONS.

1. Lipids were extracted from neurons isolated from the lateral vestibular nucleus of ox (Bos taurus L.) and the ganglia of Aplysia punctata Cuvier. 2. Thin-layer chromatography of ox-neuron lipid revealed three major fractions corresponding to neutral lipid, phosphatidylethanolamine and phosphatidylserine. Part of the phosphatidylethanolamine was present as the plasmalogen. 3. Aplysia-neuron lipid contained neutral lipid, phosphatidylethanolamine and phosphatidylserine. Both phospholipids appeared to be present predominantly as the plasmalogen form. 4. The fatty acids of alkali-labile lipids of ox neurons were examined by gas-liquid chromatography. The major fatty acids were oleic acid, stearic acid and palmitic acid.

Animals↗
PubMed1990

Conditions for growing Mycoplasma canadense and Mycoplasma verecundum in a serum-free medium.

Mycoplasma canadense and Mycoplasma verecundum were cultured in a serum-free medium containing bovine serum albumin, cholesterol, oleic acid, and palmitic acid in order to avoid the addition of horse serum. Growth was detected by measurement of A640 and by colony formation. The level of growth attained in this medium was less than that obtained in the horse serum-supplemented media, but colonies retained their distinctive morphology.

Bacteriological Techniques↗
PubMed1987

Free fatty acids alter calcium binding: a cause for misinterpretation of serum calcium values and hypocalcemia in critical illness.

FFAs are bound with calcium on the albumin molecule. We hypothesized that changes in circulating FFA levels during critical illness altered calcium-albumin binding. We found that serum from both normal subjects and critically ill patients contained an ether-extractable factor which lowered ionized calcium concentrations and increased albumin-calcium binding. This factor was found in higher concentrations in serum from ill patients. Oleic acid and palmitic acid increased albumin-calcium binding from 2-28% in a dose-dependent manner when added in vitro to calcium-albumin solutions. Scatchard analysis demonstrated that 0.1 mM oleic acid increased the number of calcium-binding sites on the albumin molecule (from three to five sites per molecule) without altering binding affinity. A similar effect was found when we performed Scatchard analyses of ether extracts in serum from three critically ill patients (number of calcium-binding sites increased from three to six). We also found that lipid infusions (during parenteral nutrition) lowered mean serum ionized calcium values in six critically ill patients [4.6 +/- 0.2 (+/- SEM) to 4.1 +/- 0.2 mg/dL; P less than 0.05]. These data support the concept that FFAs increase calcium binding to the albumin molecule. Alterations in FFA concentrations during critical illness may contribute to the poor correlation between corrected total serum calcium and ionized calcium concentrations in critically ill patients. In addition, acute elevations in circulating FFA concentrations may contribute to hypocalcemia in patients with defects in bone calcium mobilization.

Acute Disease↗
PubMed1990

Influence of dietary intake of energy and carbohydrate on the proportion of saturated and monounsaturated fatty acids in adipose tissue of middle aged men.

The fatty acid composition of subcutaneous tissue has been determined in a population sample of apparently healthy middle aged men from Southern Italy. Dietary appraisal has been carried out by evaluating the usual pattern of food consumption during the year preceding the interview. The whole population sample was subdivided into three tertiles on the basis of the energy intake by the different individuals. The proportion of adipose tissue polyunsaturated fatty acids was relatively low in the high energy tertile III and high in the low energy tertile reflecting parallel differences in the intake of polyunsaturated fatty acids. The percentage of monounsaturated fatty acids (mainly oleic acid) was relatively high (p less than 0.01) and that of saturated fatty acids (mainly palmitic acid) relatively low (p less than 0.05) in the high energy tertile (III) as compared to the low energy tertile (I); these differences were independent of the amount and type of dietary fatty acids. Total energy was positively correlated (r = .87, p less than 0.01) to carbohydrate intake (g/day). Dietary carbohydrates (g/day) were inversely related to adipose tissue saturated fatty acids (r = -.40, p less than 0.001) and directly correlated to adipose tissue monounsaturated fatty acids (p = .40, p less than 0.001). Carbohydrate intake was related to adipose tissue monounsaturated and saturated fatty acids independently of daily energy intake. On the other hand when the influence of dietary carbohydrates was eliminated, no correlation was detectable any longer between energy intake and adipose tissue fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed2005

Analysis of fatty acid composition in human bone marrow aspirates.

In the present study, the fatty acid composition of bone marrow aspirates and serum phospholipids in nine patients with hematologic diseases was investigated, and the effect of fatty acids on osteoblast differentiation in ST2 cells was examined. The concentrations of oleic acid and palmitic acid were significantly higher in bone marrow aspirates than in serum phospholipids, but the concentrations of other fatty acids did not differ. The rate of alkaline phosphatase positive ST2 cells induced by BMP2 was significantly increased by oleic acid, but was unaffected by the presence or absence of palmitic acid. We conclude that the fatty acid composition of bone marrow aspirates differs from that of serum phospholipids. This difference may affect osteoblast differentiation in the bone marrow microenvironment.

Adipocytes↗
PubMed1983

Binding of streptococcal lipoteichoic acid to fatty acid-binding sites on human plasma fibronectin.

The ability of Streptococcus pyogenes lipoteichoic acid and palmitic acid to bind to purified human plasma fibronectin was investigated. Initial studies indicated that intact fibronectin formed soluble complexes with lipoteichoic acid, resulting in a change in the mobility of fibronectin in an electrical field. Fibronectin covalently linked to agarose beads bound radiolabeled lipoteichoic acid in the acylated form but not in the deacylated form. An 18-M excess of fibronectin inhibited binding of lipoteichoic acid to the immobilized protein by 92%. Fibronectin-bound [(3)H]lipoteichoic acid could be specifically eluted with unlabeled lipoteichoic acid, as well as by fatty acid-free serum albumin. Serum albumin, which is known to contain fatty acid-binding sites capable of binding to the lipid moieties of lipoteichoic acid, inhibited the binding of lipoteichoic acid to fibronectin in a competitive fashion. The fibronectin-bound lipoteichoic acid could be eluted by 50% ethanol and various detergents but not by 1.0 M NaCl, various amino acids, or sugars. Similarly, radiolabeled palmitic acid adsorbed to fibronectin could be eluted with 50% ethanol but not with 1.0 M NaCl. Fibronectin adsorbed to a column of palmityl-Sepharose was eluted with 50% ethanol in 0.5% sodium dodecyl sulfate but not with 1.0 M NaCl or 1% sodium dodecyl sulfate alone. The binding of lipoteichoic acid to fibronectin followed first-order kinetics and was saturable. A Scatchard plot analysis of the binding data indicated a heterogeneity of lipoteichoic acid-binding sites similar to that previously found for serum albumin. Nevertheless, fibronectin contains at least one population of high-affinity binding sites for lipoteichoic acid. The binding affinity (nKa approximately 250 muM(-1)) is 2 orders of magnitude greater than the binding affinity of serum albumin. These data suggest that human plasma fibronectin contains specific binding sites for fatty acids and that lipoteichoic acid binds to these sites by way of its glycolipid moiety.

Binding Sites↗
PubMed2002

Biosynthesis of triacylglycerol molecular species in an oleaginous fungus, Mortierella ramanniana var. angulispora.

The incorporation of radiolabeled lipid precursors into triacylglycerol (TG) molecular species in Mortierella ramanniana var. angulispora, an oleaginous fungus, was studied to determine the biosynthetic pathways for TG molecular species. Radiolabeled TG molecular species were separated and quantified by reverse-phase high performance liquid chromatography with a radioisotope detector. The major TG molecular species labeled by [1-(14)C]oleic acid at 30 degrees C were OOP, OOO, and OPP (TG molecular species designations represent three constituent acyl groups. G, gamma-linolenic acid; L, linoleic acid; O, oleic acid; S, stearic acid; P, palmitic acid), which were abundant TG molecular species in this fungus. The incorporation of [1-(14)C]oleic acid at 15 degrees C into these molecular species was the same, while that into most other species was decreased, suggesting that biosynthesis of major molecular species such as OOP, OOO, and OPP differs from that of other TG molecular species. [1-(14)C]Linoleic acid incorporation indicated that the major labeled molecular species were LOP and LOO, which may be due to acylation of oleoyl, palmitoyl-glycerol, or dioleoyl-glycerol by exogenous linoleic acid. This is basically the same mechanism as for OOP and OOO biosynthesis from exogenous oleic acid. [(14)C(U)]Glycerol incorporation suggested that TG molecular species containing palmitic acid such as OPP were more readily synthesized through the de novo pathway. Further experiments involving inhibitors such as sodium azide and cerulenin suggested that OOO biosynthesis included a mechanism differing from that in the cases of OOP and OPP. Trifluoperazine, which inhibits the conversion from phosphatidic acid to TG, decreased [1-(14)C]oleic acid incorporation into all molecular species, suggesting that the incorporation into all molecular species included the de novo TG biosynthetic pathway via phosphatidic acid. These results revealed that the biosynthetic pathways for TG molecular species can be classified into several groups, which exhibit different sensitivities to low temperature and inhibitors of lipid metabolism. This implies that the composition of TG molecular species is regulated through different biosynthetic pathways responsible for specific TG molecular species, providing a new insight into the biosynthesis of TG molecular species.

Carbon Radioisotopes↗
PubMed2003

Effect of fatty acids on expression of endothelial leukocyte adhesion molecules.

BACKGROUND: With respect to linoleic acid both beneficial and proatherogenic effects have been described. However, the effect on expression of cell adhesion molecules on human coronary artery endothelial cells (HCAEC) is not yet established. The aim of the experiments was to evaluate the influence of linoleic acid in comparison with palmitic acid regarding the cytokine-induced expression of endothelial leukocyte adhesion molecules (intercellular cell adhesion molecule-1 ICAM-1, vascular cell adhesion molecule-1 VCAM-1, E-selectin). METHODS: HCAEC were cultured in microvascular endothelial cell growth medium. In the experiments, the cells were preincubated with linoleic acid and palmitic acid, respectively (10 micro mol/l, 2 days) or under control conditions, after which interleukin- 1alpha (IL-1alpha, 10 ng/ml in the test medium) was added for 1 day. The monoclonal antibodies used were fluorescein isothiocyanate (FITC)- labeled anti-ICAM-1, FITC-labeled anti-VCAM-1, and FITC-labeled anti-E-selectin. Expression was analyzed by flow cytofluorimetry. Next, to examine the effects of fatty acids on adhesion of monocytes to endothelial cells, adhesion experiments with the monocytic U 937 cell line were performed. RESULTS AND CONCLUSIONS: IL-1alpha increased ICAM-1,VCAM-1, and E-selectin expression compared to controls. Incubation with IL-1alpha together with linoleic acid reduced the expression of ICAM-1 and VCAM-1 in contrast to palmitic acid. Furthermore, in the presence of linoleic acid a tendency of diminished adhesion of monocytes is seen. The results indicate that a reduced expression of cell adhesion molecules may be relevant to the antiatherogenic effects of linoleic acid. This is in contrast to the properties of palmitic acid.

Cell Adhesion↗
PubMed1990

On the nature of the uncoupling effect of fatty acids.

The effect of palmitic acid on the electrical potential differences delta psi across the inner mitochondrial membrane appears to depend on the medium in which mitochondria are incubated. In medium A (cf. Luvisetto et al. (1987), Biochemistry, 26, 7332-7338) delta psi decreases much more than in medium B (cf. Rottenberg and Hashimoto (1986), Biochemistry, 25, 1747-1755) at concentrations of fatty acid which equally stimulate the rate of respiration in state 4. Valinomycin and NaCl were both present in medium B and absent in medium A. However, in both media the pattern of the P/O ratio as a function of antimycin in the presence of a constant amount of palmitic acid or of FCCP shows similar behaviour. We conclude that in both media palmitic acid increases the membrane conductance to protons, but for unclear reasons the delta psi assay fails to measure the decline of delta psi in medium B. However, the increase in membrane conductance induced by palmitic acid does not quantitatively account for the stimulation of the rate of respiration.

Adenosine Triphosphate↗
PubMed2001

Palmitic and stearic acids similarly affect plasma lipoprotein metabolism in cynomolgus monkeys fed diets with adequate levels of linoleic acid.

This study was designed to evaluate whether the exchange of specific saturated fatty acids [SFA; palmitic acid (16:0) for stearic acid (18:0)] would differentially affect plasma lipids and lipoproteins, when diets contained the currently recommended levels of total SFA, monounsaturated fatty acids and polyunsaturated fatty acids (PUFA). Ten male cynomolgus monkeys were fed one of two purified diets (using a cross-over design) enriched either in 16:0 (palmitic acid diet) or 18:0 (stearic acid diet). Both diets provided 30% of energy as fat (SFA/monounsaturated fatty acid/PUFA: 1/1/1). The palmitic acid and stearic acid diets were based on palm oil or cocoa butter (59% and 50% of the total fat, respectively). By adding different amounts of sunflower, safflower and olive oils, an effective exchange of 16:0 for 18:0 of approximately 5% of energy was achieved with all other fatty acids being held constant. Monkeys were rotated through two 10-wk feeding periods, during which time plasma lipids and in vivo lipoprotein metabolism (following the simultaneous injection of (131)I-LDL and (125)I- HDL were evaluated). Plasma triacyglycerol (0.40 +/- 0.03 vs. 0.37 +/- 0.03 mmol/L), plasma total cholesterol (3.59 +/- 0.18 vs. 3.39 +/- 0.23 mmol/L), HDL cholesterol (1.60 +/- 0.16 vs 1.53 +/- 0.16 mmol/L) and non-HDL cholesterol (2.02 +/- 0.26 vs. 1.86 +/- 0.23 mmol/L) concentrations did not differ when monkeys consumed the palmitic acid and stearic acid diets, respectively. Plasma lipoprotein compositional analyses revealed a higher cholesteryl ester content in the VLDL fraction isolated after consumption of the stearic acid diet (P < 0.10), as well as a larger VLDL particle diameter (16.3 +/- 1.7 nm vs. 13.8 +/- 3.6 nm; P < 0.05). Kinetic analyses revealed no significant differences in LDL or HDL transport parameters. These data suggest that when incorporated into diets following current guidelines, containing adequate PUFA, an exchange of 16:0 for 18:0, representing approximately 11 g/(d.10.46 mJ) [ approximately 11 g/(d.2500 kcal)] does not affect the plasma lipid profile and has minor effects on lipoprotein composition. Whether a similar effect would occur in humans under comparable dietary conditions remains to be established.

Animals↗
PubMed1994

Stimulation of fatty acid oxidation by a 3-thia fatty acid reduces triacylglycerol secretion in cultured rat hepatocytes.

The present work shows that when mitochondrial beta-oxidation is stimulated by the hypolipemic, non-beta-oxidizable fatty acid analogue tetradecylthioacetic acid, there is a decrease in the secretion of triacylglycerol in cultured rat hepatocytes. In order to study the effects of tetradecylthioacetic acid in cells with different fatty acid oxidation rates, cells were grown without or with L-carnitine supplement or with addition of the beta-oxidation inhibitor L-aminocarnitine. In cells grown without and with L-carnitine in the medium, the oxidation of [1-14C]oleic acid was stimulated by tetradecylthioacetic acid, whereas it was not significantly changed by palmitic acid. In cells grown with L-aminocarnitine, oxidation of [1-14C]oleic acid was almost abolished both in the absence and in presence of tetradecylthioacetic acid. The effect of tetradecylthioacetic acid and palmitic acid on incorporation of [1-14C]oleic acid into triacylglycerol was similar under all conditions. In the presence of L-carnitine, secretion of oleic acid-labeled triacylglycerol was reduced significantly more by tetradecylthioacetic acid than by palmitic acid. The effects of tetradecylthioacetic acid and palmitic acid on secretion of oleic acid-labeled triacylglycerol were reversed in cells grown with L-aminocarnitine, where palmitic acid was the stronger inhibitor. These results were substantiated by determination of mass of triacylglycerol secreted. It is concluded that tetradecylthioacetic acid reduces secretion of triacylglycerol from rat hepatocytes mainly by acutely stimulating fatty acid oxidation.

Animals↗
PubMed2001

Comparative quantitative fatty acid analysis of triacylglycerols using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and gas chromatography.

Quantitative analyses of fatty acids from five triacylglycerol products, coconut oil, palm kernel oil, palm oil, lard and cocoa butter, were carried out using two analytical methods: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and gas chromatography (GC), in an effort to validate the application of MALDI-TOFMS in quantitative fatty acid analysis. For the GC analysis, transmethylated products were used, whereas, for the MALDI-TOF analysis, saponified products were used. Under MALDI-TOF conditions, the acids were detected as sodiated sodium carboxylates [RCOONa + Na](+) consistent with the mode of ionization that was previously reported. Thus, the MALDI-TOF mass spectrum of saponified coconut oil showed the presence of sodiated sodium salts of caprylic acid (7.5 +/- 0.67, m/z 189), capric acid (6.9 +/- 0.83, m/z 217), lauric acid (47.8 +/- 0.67, m/z 245), myristic acid (20.4 +/- 0.51, m/z 273), palmitic acid (9.8 +/- 0.47, m/z 301), linoleic acid (0.9 +/- 0.07, m/z 325), oleic acid (4.8 +/- 0.42, m/z 327) and stearic acid (2.0 +/- 0.13, m/z 329). Saponified palm kernel oil had a fatty acid profile that included caprylic acid (3.5 +/- 0.59), capric acid (4.7 +/- 0.82), lauric acid (58.6 +/- 2.3), myristic acid (20.9 +/- 1.5), palmitic acid (7.2 +/- 1.1), oleic acid (3.8 +/- 0.62) and stearic acid (1.2 +/- 0.15). Saponified palm oil gave myristic acid (0.83 +/- 0.18), palmitic acid (55.8 +/- 1.7), linoleic acid (4.2 +/- 0.51), oleic acid (34.5 +/- 1.5), stearic acid (3.8 +/- 0.26) and arachidic acid (0.80 +/- 0.22). Saponified lard showed the presence of myristic acid (1.5 +/- 0.24), palmitic acid (28.9 +/- 1.3), linoleic acid (13.7 +/- 0.67), oleic acid (38.7 +/- 1.4), stearic acid (12.8 +/- 0.64) and arachidic acid (2.4 +/- 0.35). Finally, for saponified cocoa butter, the fatty acid distribution was: palmitic acid (32.3 +/- 1.0), linoleic acid (2.6 +/- 0.35), oleic acid (34.9 +/- 1.7) and stearic acid (30.3 +/- 1.6). Quantitative gas chromatographic analysis of the corresponding methyl esters from these triacylglycerol products yielded data that were mostly in agreement with the MALDI-TOFMS data. The MALDI-TOF experiment, however, proved to be superior to the GC experiment, particularly with regard to baseline resolution of unsaturated acids. Furthermore, the ability of MALDI-TOFMS to detect low concentrations of fatty acids rendered it more sensitive than the GC methodology.

Animals↗
PubMed2006

Enzymatic modification of cassava starch by bacterial lipase.

Enzymatic modification of starch using long chain fatty acid makes it thermoplastic suitable for a myriad of industrial applications. An industrial lipase preparation produced by Burkholderia cepacia (lipase PS) was used for modification of cassava starch with two acyl donors, lauric acid and palmitic acid. Reactions performed with palmitic acid by liquid-state and microwave esterification gave a degree of substitution (DS) of 62.08% (DS 1.45) and 42.06% (DS 0.98), respectively. Thermogravimetric analysis showed that onset of decomposition is at a higher temperature (above 600 degrees Celsius) for modified starch than the unmodified starch (280 degrees Celsius). Modified starch showed reduction in alpha-amylase digestibility compared to native starch (76.5-18%). Swelling power lowered for modified starch as esterification renders starch more hydrophobic, making it suitable for biomedical applications as materials for bone fixation and replacements, carriers for controlled release of drugs and bioactive agents. Thus enzymatic esterification is ecofriendly.

Burkholderia cepacia complex↗
PubMed2006

Study on the antiinflammatory activity of methanol extract from seagrass Zostera japonica.

Methanolic extracts from the seagrass Zostera japonica were extracted successively using n-hexane (n-C(6)H(14)), dichloromethane (CH(2)Cl(2)), ethyl acetate (EtOAc), and water to give the n-C(6)H(14) (16.8%), CH(2)Cl(2) (40.6%), EtOAc (34.1%), and H(2)O (8.5%) soluble fractions, respectively. We have demonstrated that the hexane fraction has the highest capacity to inhibit proIL-1beta expression as compared to other fractions in lipopolysaccharides (LPS)-stimulated J774A.1 murine macrophages. Further analysis of the composition and antiinflammatory activity of the subfraction H5 from hexane fraction showed that it had the best antiinflammatory capacity and that it's major constituents were fatty acids, including palmitic acid methyl ester (21.5%), palmitic acid (24.02%), linoleic acid methyl ester (13.09%), oleic acid methyl ester (8.41%), and linoleic acid (7.93%), respectively. H5 inhibited LPS-induced TNFalpha, IL-1beta, and IL-6 in a dose-dependent manner, suggesting that H5 is bioactive in antiinflammation in vitro. This study is the first to report the antiinflammatory activity of extracts obtained from the seagrass Z. japonica.

Animals↗
PubMed1971

Formation of 1-O-2'-hydroxyalkyl glycerophosphatides from 1,2-heptadecanediol in myelinating brain.

1,2-Heptadecanediol-2-(14)C was administered intracerebrally to 18-day-old rats, and its incorporation, after 8 hr, into the individual aliphatic moieties of the ethanolamine glycerophosphatides was determined. Much of the radioactivity was found in a lipid fraction identified as 1-O-2'-hydroxyheptadecyl glycerol. Evidence is presented that a major portion of the precursor was incorporated into 1-O-2'-hydroxyheptadecyl-2-acyl ethanolamine phosphatides. Some of the diol administered was degraded to palmitic acid. The palmitic acid-1-(14)C derived from 1,2-heptadecanediol-2-(14)C apparently served as precursor for stearic and oleic acids, which were found as acyl groups, and for the biosynthesis of the corresponding O-alkyl and O-alk-1-enyl glycerols. The data presented prove that biological dehydration of 1-O-2'-hydroxyalkyl glycerophosphatides to the corresponding plasmalogens does not occur in myelinating brain.

Acylation↗
PubMed1981

Source of arachidonic acid for prostaglandin synthesis in Madin-Darby canine kidney cells.

Madin-Darby canine kidney cells deacylate arachidonic acid from cellular phospholipids in response to stimulation with 12-O-tetradecanoyl-phorbol-13-acetate and convert the free arachidonic acid to prostaglandins. We have used this system to determine which phospholipids serve as donors of the free arachidonic acid. The cells were labeled with [3H]arachidonic acid and [14C]palmitic acid which were preferentially incorporated into phosphatidylethanolamine and phosphatidylcholine, respectively. 12-O-Tetradecanoyl-phorbol-13-acetate stimulation caused a marked deacylation of arachidonic acid from phospholipids including 1-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine; phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and phosphatidylcholine were also donors of arachidonate. A smaller percentage of the [14C]palmitic acid was lost from phospholipids after stimulation and indicates that the stimulated deacylation of phospholipids is preferential for [3H]arachidonic acid compared to [14C]palmitic acid. Analysis of the cellular phospholipid acyl composition demonstrated that 12-O-tetradecanoyl-phorbol-13-acetate stimulation caused a marked decrease in the content of arachidonic acid and an increase in saturated and monounsaturated fatty acids. These findings suggest that the phospholipids which serve as arachidonic acid donors are rapidly reacylated with more saturated fatty acids.

Animals↗
PubMed1991

Fast translocation of phosphatidylcholine to the outer membrane leaflet after its synthesis at the inner membrane surface in human erythrocytes.

The translocation rate of [14C]phosphatidylcholine to the outer membrane leaflet of human erythrocytes after its primary synthesis from lysophosphatidylcholine by acylation with 14C-labeled oleic or palmitic acid in the inner leaflet has been measured by following the time-dependent increase of cleavability of 14C-labeled phospholipids by external phospholipase A2 (5 min, 37 degrees C). Immediately after a short acylation time period of 10 min about 20% of the newly synthesized [14C]phosphatidylcholine are already detectable in the outer leaflet. After an incubation of 1 h at 37 degrees C following 10 min of acylation the fractions of labeled and native phosphatidylcholine accessible to the lipase are identical, which demonstrates that [14C]phosphatidylcholine has attained the same asymmetric distribution as its endogenous analogue. The calculated halftime of the outward translocation is about 20 min and its activation energy is low, 30 kJ/mol. Translocation is inhibited by a 5 min treatment with phenylglyoxal following acylation. A fast translocation is not observed for newly synthesized phosphatidylethanolamine. Results suggest a selective, protein-mediated outward translocation of newly synthesized phosphatidylcholine.

Acylation↗