Distribution of cis-Vaccenic Acid in Chinese Hamster V79-R Cells

V79-R Cells grown in lipid-free medium contained octadecenoic acids as the major fatty acids esterified to lipids. Octadecenoic acids were composed of two positional isomers, oleic and cis-vaccenic acids. The distribution of oleic and cis-vaccenic acids was altered by the addition of various fatty acids to the medium. There was no difference in the distribution of oleic and cis-vaccenic acids in phospholipids between mitochondria and microsomes. Cardiolipin contained higher amounts of palmitoleic and cis-vaccenic acids than did other lipids.     

Enzymatic basis for the formation of pulmonary surfactant lipids by acyltransferase systems

An enzymatic basis for the formation of pulmonary surfactant lipids in rat has been presented. The free fatty acid pools in lung and liver consisted mainly of palmitic, stearic, oleic, and arachidonic acids with relatively less polyunsaturated fatty acids in lung than in liver. The acyl chain specificities of the acyl-CoA synthetase systems in lung and liver microsomes were similar in that most of fatty acids found in the free fatty acid pools were effectively activated by both systems. The acyl-CoA pools had compositions significantly different from those of the free fatty acid pools in lung and liver with relatively more stearate and less polyunsaturated fatty acids. The lung acyl-CoA pool contained mainly palmitate (29%), stearate (31%), and oleate (22%) with very little polyunsaturated acyl-CoAs to compete for esterification. The use of an equimolar mixture of palmitoyl-CoA and arachidonoyl-CoA to acylate the endogenous monoacyl-glycerophosphocholine isomers in the lung microsomes yielded both the 2-palmitate and 2-arachidonate diacyl forms, whereas the major products formed by liver microsomes were the 2-arachidonate and 1-palmitate forms. These results indicate that the 1-acyl isomer is the major monoacyl-glycerophosphocholine species serving as substrate in lung microsomes, whereas both 1-acyl and 2-acyl isomers are present in liver microsomes. Thus, the enrichment of saturated and oligoenoic acids in the acyl-CoA pool combined with the predominance of the 1-acyl isomer in the acyl acceptor pool and the relatively higher selectivity for palmitoyl-CoA by the 1-acyl-GPC acyltransferase activity of lung constitute an important basis for attributing some of the formation of pulmonary surfactant lipids in rats to acyltransferase action.     

The effect of polychlorinated biphenyls (PCBs) on the membrane lipids of Pseudomonas stutzeri

In this study we examined the effect of polychlorinated biphenyls (PCBs) on biomass production of a PCB-degrading Pseudomonas stutzeri, and on the fatty acid profile of its major membrane lipids. Growth based on biomass weight was stimulated when PCBs were added at the time of inoculation, but PCB addition three days after inoculation led to a significant decrease in biomass. Simultaneous addition of PCBs plus biphenyl or PCBs plus carvone negatively affected P. stutzeri biomass (addition of biphenyl or carvone at the time of inoculation and PCBs to three-day-old culture). In the presence of PCBs alone the amount of the prevalent fatty acids C16:0 and C17-cyclopropyl fatty acid (C17-CP) of P. stutzeri in total and neutral lipids was significantly reduced. When PCBs were added together with carvone (carvone at the time of inoculation and PCBs after three days) a significant reduction of these fatty acids was obtained, but, in addition, oleic, cis-vaccenic, and cyclononadecanic (C19-CP) acids were increased. When PCBs were combined to biphenyl the prevalent fatty acids were reduced and oleic, cis-vaccenic, and cyclononadecanic acids were increased in total and neutral lipids. Addition of 3-chlorobenzoic acid led to a significant growth inhibition and to the production of oleic and cis-vaccenic acids in the membrane fraction phosphatidylcholine.     

Effects of perfluorocarboxylic acids on the activities of acyl-CoA elongations in vivo and in vitro

Effects of perfluorocarboxylic acids (PFCAs) on proportions of oleic acid and cis-vaccenic acid through acyl-CoA chain elongation systems have been studied in the liver of rats. Administration of PFCAs caused a significant increase in palmitoyl-CoA chain elongation activity while these chemicals did not affect palmitoleoyl-CoA chain elongation activity in vivo.Condensation for both palmitoyl-CoA and palmitoleoyl-CoA were inhibited by PFCAs in vitro at the concentrations, which were physiologically found in the liver of rats treated with the PFCAs. Δ⁹ Desaturase, which catalyzes both stearoyl-CoA desaturation and palmitoyl-CoA desaturation, was induced by the treatments of rats with the PFCAs. The administration of the PFCAs to rats caused a marked increase in proportion of oleic acid, while that of cis-vaccenic acid was not affected at all. These results strongly suggest that the induced palmitoyl-CoA chain elongation by PFCAs, which exist in the liver, effectively produces oleic acid in concert with the induced stearoyl-CoA desaturase, but the inhibitory effects of PFCAs on either palmitoyl-CoA chain elongation or palmitoleoyl-CoA chain elongation are not crucial for the formation of the elongated fatty acids in vivo.     

A comparison of the metabolic fate of Fatty acids of different chain lengths in developing oilseeds

To determine if medium and long chain fatty acids can be appropriately metabolized by species that normally produce 16 and 18 carbon fatty acids, homogenates of developing Cuphea wrightii, Carthamus tinctorius, and Crambe abyssinica seeds were incubated with radiolabeled lauric, palmitic, oleic, and erucic acids. In all three species, acyl-CoA synthetase showed broad substrate specificity in synthesis of acyl-coenzyme A (CoA) from any of the fatty acids presented. In Carthamus, two- to fivefold less of the foreign FAs, lauric, and erucic acid was incorporated into acyl-CoAs than palmitic and oleic acid. Lauric and erucic acid also supported less glycerolipid synthesis in Carthamus than palmitic and oleic acid, but the rate of acyl-CoA synthesis did not control rate of glycerolipid synthesis. In all species examined, medium and long chain fatty acids were incorporated predominantly into triacylglycerols and were almost excluded from phospholipid synthesis, whereas palmitic and oleic acid were found predominantly in polar lipids. However, the rate of esterification of unusual fatty acids to triacylglycerol is slow in species that do not normally synthesize these acyl substrates.     

Regioisomer separation and identification of triacylglycerols containing vaccenic and oleic acids,and α- and γ-linolenic acids,in thermophilic cyanobacteria Mastigocladus laminosus and Tolypothrix sp.

Reversed phase liquid chromatography–atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/APCI-MS) was used for direct analysis of triacylglycerols (TAGs) from different strains of the cyanobacteria Mastigocladus laminosus, Tolypothrix cf. tenuis and Tolypothrix distorta. This technique enabled us to identify and quantify the specific molecular species of TAGs directly from lipid extracts of the cyanobacteria. The regioisomeric series of TAGs having α-linolenic and γ-linolenic and also oleic and cis-vaccenic acids were separated by RP-HPLC and identified by APCI-MS. M. laminosus produced only a few molecular species of TAGs, including both isomers of octadecenoic (oleic and vaccenic) acid, while T. distorta contained tens of molecular species of TAGs having FAs with up to four double bonds (stearidonic acid and including also its positional isomer, i.e. 3,6,9,12-octadecatetraenoic acid) and both positional isomers (α and γ) of linolenic acids. Individual strains of both cyanobacteria exhibited different contents of polyunsaturated fatty acids (Tolypothrix sp.) and different distribution of positional isomers of monoenoic fatty acids in TAGs (M. laminosus).     

ACCUMULATION OF OLEIC ACID IN HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE) UNDER NITROGEN STARVATION OR HIGH LIGHT IS CORRELATED WITH THAT OF ASTAXANTHIN ESTERS1

The chlorophyte Haematococcus pluvialis accumulates large quantities of astaxanthin under stress conditions. Under either nitrogen starvation or high light, the production of each picogram of astaxanthin was accompanied by that of 5 or 3–4 pg of fatty acids, respectively. In both cases, the newly formed fatty acids, consisting mostly of oleic (up to 34% of fatty acids in comparison with 13% in the control), palmitic, and linoleic acids, were deposited mostly in triacylglycerols. Furthermore, the enhanced accumulation of oleic acid was linearily correlated with that of astaxanthin. Astaxanthin, which is mostly monoesterified, is deposited in globules made of triacylglycerols. We suggest that the production of oleic acid‐rich triacylglycerols on the one hand and the esterification of astaxanthin on the other hand enable the oil globules to maintain the high content of astaxanthin esters.     

beta-Oxidation of the coenzyme A esters of elaidic, oleic, and stearic acids and their full-cycle intermediates by rat heart mitochondria.

beta-Oxidation rates for the CoA esters of elaidic, oleic and stearic acids and their full-cycle beta-oxidation intermediates and for the carnitine esters of oleic and elaidic acids were compared over a wide range of substrate and albumin concentrations in rat heart mitochondria. The esters of elaidic acid were oxidized at about half the rate of the oleic acid esters, while stearoyl-CoA was oxidized equally as rapid as oleoyl-CoA. The full-cycle beta-oxidation intermediates of elaidoyl-CoA (trans-16 : 1 delta 7, -14 : 1 delta 5, and -12 : 1 delta 3) were found to be oxidized at rates nearly equal to those for the corresponding intermediates of oleoyl-CoA. Therefore, after the first cycle of beta-oxidation, oleoyl-CoA and elaidoyl-CoA are oxidized at nearly equal rates. The activity of fatty acyl-CoA dehydrogenase was higher with elaidoyl-CoA and its full-cycle intermediates as substrates than with the corresponding cisisomers. It was concluded that the slower oxidation rate of elaidic acid is not due to slower oxidation of any of its full-cycle beta-oxidation intermediates, nor to slower activity of fatty acyl-CoA dehydrogenase, nor to outer mitochondrial carnitine acyltransferase. Possible explanations to account for the slower oxidation rate of elaidic acid are discussed.     

Synthesis of trans unsaturated fatty acids in Pseudomonas putida P8 by direct isomerization of the double bond of lipids

The phospholipids of Pseudomonas putida P8 contain monounsaturated fatty acids in the cis and trans configuration. Cells of this phenol-degrading bacterium change the proportions of these isomers in response to the addition or elimination of a membrane active compound such as 4-chlorophenol. This study undoubtedly reveals that the cis unsaturated fatty acids are directly converted into trans isomers without involvement of de novo synthesis of fatty acids. Oleic acid, which cannot be synthesized by this bacterium, was incorporated as a cis unsaturated fatty acid marker in the membrane lipids of growing cells. The conversion of this fatty acid into the corresponding trans isomer was demonstrated by gas chromatographic-mass spectrometric analysis and use of ¹⁴C-labeled oleic acid. Separation and isolation of the cellular membranes showed that the fatty acid isomerase is located in the cytoplasmic membrane of P. putida P8.Abbreviation 4-CP 4-chlorophenol     

Synthesis of Long-Chain Acyl-CoA in Chloroplast Envelope Membranes

The chloroplast envelope is the site of a very active long-chain acylcoenzyme A (CoA) synthetase. Furthermore, we have recently shown that an acyl CoA thioesterase is also associated with envelope membrane (Joyard J, PK Stumpf 1980 Plant Physiol 65: 1039-1043). To clarify the interacting roles of both the acyl-CoA thioesterase and the acyl-CoA synthetase, the formation of acyl-CoA in envelope membranes was examined with different techniques which permitted the measurement of the actual rates of acyl-CoA formation. Using [¹⁴C]ATP or [¹⁴C]oleic acid as labeled substrates, it can be shown that the envelope acyl-CoA synthetase required both Mg²⁺ and dithiothreitol. Triton X-100 slightly stimulated the activity. The specificity of the acyl-CoA synthetase was determined either with [¹⁴C]ATP or with [³H]CoA as substrates. The results obtained in both cases were similar, that is, as substrates, the unsaturated fatty acids were more effective than saturated fatty acids, the velocity of the reaction increased from lauric acid to palmitic acid, and the maximum velocity was obtained with unsaturated C₁₈ fatty acids.     

Synthesis of mixed diesters of ethanediol with N-acyl amino acids and fatty acids

Chemical synthesis of mixed diesters of ethanediol with N-acyl amino acids and fatty acids is described. The synthesis is performed in three steps: (1) preparation of N-acyl amino acids using fatty acid ester of N-hydroxyphthalimide as an acylating agent; (2) partial esterification of ethanediol with N-acyl amino acid, in tetrahydrofuran in presence of thionyl chloride; (3) further esterification of the monoester of ethanediol with a fatty acid, to a mixed diester, in presence of the same reagent.     

Lipase-catalyzed synthesis of partial glyceride

Summary Mucor miehei (IM 20) and Candida antarctica (SP 382) lipases were used for esterification of free fatty acids in the absence of organic solvent or transesterification of fatty acid methyl esters in hexane with isopropylidene glycerols. Acid catalyzed cleavage of the isopropylidene groups resulted in the formation of monoacyl glycerol (MAG) and diacyl glycerol (DAG). Both oleic (18:1 n-9) and eicosapentaenoic acid, EPA (20:5 n-3) were successfully incorporated into glycerides. Total acyl donor conversion ranged from 46.9 – 96.9% with MAG content of up to 88.5%.     

Effects of different types of polyunsaturated fatty acids on cholesterol esterification in human fibroblasts.

We have enriched human fibroblasts with oleic acid, with linoleic acid and with eicosapentaenoic acid. The accumulation of cholesteryl esters in the cells and the rate of esterification of cholesterol by microsomal acyl-CoA:cholesterol acyltransferase (ACAT) were measured in these cells. Cholesteryl ester levels were lower in cells enriched with eicosapentaenoic acid compared with cells enriched with oleate or linoleate. We also observed significantly lower ACAT activities in the microsomes from fibroblasts enriched with the n-3 polyunsaturated fatty acids relative to cells enriched with oleic acid or linoleic acid. We suggest that the presence of n-3 polyunsaturated fatty acids might suppress cholesteryl ester accumulation and inhibit atherogenesis.     

Studies on Moss Spores. IV. Mass Spectrometric Identification of Saturated and Monoenoic Long Chain Fatty Acids in the Triglyceride Fraction of Polytrichum commune Spores

The saturated long chain fatty acid methyl esters of the triglyceride fraction of Polytrichum commune spores were separated by silver nitrate TLC and identified by a combination of gas chromatographic-mass spectrometric technique. The saturated fatty acid methyl esters were straight-chained, and even-numbered with carbon numbers ranging from 12 to 26 or odd-numbered with carbon numbers ranging from 13 to 25. The major components of the fraction containing saturated fatty acid methyl esters were methyl palmitate and methyl stearate. The fatty acid methyl esters of the monoenoic fraction isolated by silver nitrate TLC were converted to TMSO derivates which were analysed by gas chromatography-mass spectrometry. The analysis gave evidence of positional isomers. The fraction contained the following straight chain monoenoic fatty acid methyl ester isomers: methyl 7-cis-hexadecenoate, methyl 9-cis-hexadecenoate, methyl 9-cis-heptadecenoate, methyl 9-cis-octadecenoate, methyl 11-cis-octadecenoate, and methyl 11-cis-eicosenoate. The major components were methyl 9-cis-octadecenoate and methyl 7-cis-hexadecenoate.     

The Effect of Dietary Sterol on the Activity of Fatty Acid Desaturases Isolated from Tetrahymena setosa

Tetrahymena setosa has a nutritional requirement for micro amounts of sterol, a requirement which is also satisfied by relatively large amounts of either intact phospholipids or a mixture of unsaturated fatty acids normally found in these ciliates. Three microsomal fatty acyl-CoA desaturases have been isolated from T. setosa and partially characterized. These enzymes which can account for the formation of the majority of the ciliate's unsaturated fatty acids, include: a Δ9, a Δ12 and a Δ6 desaturase which catalyze the transformation of stearoyl-CoA to oleic acid, of oleoyl-CoA to linoleic acid and of linoleoyl-CoA to ?-linolenic acid, respectively. The stearoyl CoA desaturase required NAD (or NADP), ATP and free CoA; the Δ6 and Δ12 desaturases required NADP, but not ATP or CoA. Cellular levels of the three desaturases were highest in mid-logarithmic phase cells and lowest in stationary phase cells. In order to determine if there was a relationship between the sterol requirement and the ability of the organism to desaturate, T. setosa was grown in a synthetic medium supplemented with either cholesterol or a phospholipid which permits growth in the absence of cholesterol, or with both phospholipid and cholesterol. Cells grown with phospholipid alone had only half as much stearoyl-CoA and oleoyl-CoA desaturase activity as cells of identical culture age grown either on cholesterol alone or on cholesterol plus phospholipid.     

Incorporation of lipoxygenase products into cholesteryl esters by acyl-CoA:cholesterol acyltransferase in cholesterol-rich macrophages.

Macrophages which were incubated with acetylated low-density lipoproteins, resulting in cholesteryl ester accumulation, incorporated the monohydroxyeicosatetraenoic acids (5-, 15-, and 12-HETEs) into cholesteryl esters. The esterification of these hydroxy fatty acids to cholesterol by total membrane preparations of cholesterol-rich macrophages was dependent on the synthesis of the fatty acyl-CoA derivative, and was catalysed by acyl-CoA:cholesterol acyltransferase (ACAT). Stimulation of membrane ACAT activity by 25-hydroxycholesterol increased the synthesis of cholesteryl 12-HETE by 40%. In contrast, inhibiting ACAT activity by progesterone and compound 58-035 decreased cholesteryl 12-HETE production by 60% and 90% respectively. Although 5-, 15- and 12-HETE were esterified to cholesterol by ACAT, these monohydroxy fatty acids were less optimal as substrates compared with oleic acid or arachidonic acid. The hydrolysis and release of 12-HETE and the other monohydroxyeicosatetraenoic acids from intracellular cholesteryl esters and phospholipids occurred at a faster rate than for the more conventional fatty acids, oleate and arachidonate. Cholesteryl esters which contain hydroxy fatty acids therefore provide only a transient storage for lipoxygenase products, as these fatty acids are released into the medium as readily as hydroxy fatty acids found in phospholipids and triacylglycerols. The data provide evidence, for the first time, of an ACAT-dependent esterification of the lipoxygenase products 5-, 15- and 12-HETEs to cholesterol in the macrophage-derived foam cell. The channelling of these monohydroxy fatty acids to cholesteryl esters provides a mechanism which can alter the amount of lipoxygenase products incorporated into cellular phospholipids, thus averting deleterious changes to cell membranes. ACAT, by catalysing the esterification of monohydroxyeicosatetraenoic acids to cholesterol, could play a key role in regulating the amount of lipoxygenase products in the pericellular space of the cholesterol-enriched macrophage.     

Oleyl Oleate and Homologous Wax Esters Synthesized Coordinately from Oleic Acid by Acinetobacter and Coryneform Strains

Newly isolated Acinetobacter (NRRL B-14920, B-14921, B-14923) and coryneform (NRRL B-14922) strains accumulated oleyl oleate and homologous liquid wax esters (C_30:2–C_36:2) in culture broths. Diunsaturated oleyl oleate preponderated in 75 mg liquid wax esters (280 mg lipid extract) recovered from 100-ml cultures of Acinetobacter B-14920 supplemented with 810 mg oleic acid–oleyl alcohol. With soybean oil instead of oleic acid, wax esters (260 mg) were increased to approximately 50% of the lipid extract. Production of wax esters by cultures supplemented with combined fatty (C₈–C₁₈) alcohols and acids suggests a coordinated synthesis whereby the exogenous alcohol remains unaltered, and the fatty acid is partially oxidized with removal of C₂ units before esterification. Consequently, C₈–C₁₈ primary alcohols control chain lengths of the wax esters. Exogenous fatty acids are presumed to enter an intracellular oxidation pool from which is produced a homologous series of liquid wax esters.     

Composition and synthesis of fatty acids in atherosclerotic aortas of the pigeon

The composition, synthesis, and esterification of fatty acids were studied in aortas of White Carneau and Show Racer pigeons after perfusion of the aortas with a medium containing acetate-1-(14)C. For both breeds of pigeons the principal change in aortic fatty acids, in response to an atherogenic diet, was a marked increase in the percentage of oleic acid in the cholesteryl ester fraction. In atherosclerotic aortas incorporation of acetate-1-(14)C into the phospholipid and glyceride fractions increased 2-fold, while a much greater increase (up to 10-fold) was seen in incorporation into cholesteryl esters. In those birds receiving the atherogenic diet, palmitic acid accounted for approximately 50% of the fatty acid radioactivity, compared with approximately 25% from control aortas. Calculation of fatty acid synthesis showed the major newly synthesized fatty acids to be stearic acid in the phospholipid fraction; stearic, palmitic, and oleic acids in the glycerides; and oleic acid in the cholesteryl esters. The pattern of fatty acid synthesis was closely similar to the actual fatty acid composition of the aorta. In atherosclerotic aortas an increased synthesis of all fatty acids was seen, but the greatest increase was seen in the synthesis of oleic acid and its esterification to cholesterol.