Positional Distribution Of Fatty Acids Research Articles

Enzymatic bases for the fatty acid positioning in phospholipids of Brevibacterium ammoniagenes

Positional distribution of fatty acids in phospholipids from Brevibacterium ammoniagenes was analyzed to find that phosphatidylethanolamine consisted mainly of 1-saturated acyl 2-unsaturated acyl species while phosphatidylglycerol consisted mainly of 1-unsaturated acyl 2-saturated acyl species. Three acyltransferase systems were characterized in a membrane preparation—the acylations of glycerophosphate, 1-acyl-glycerophosphate, and 2-acyl-glycerophosphate—which appeared to be catalyzed by different enzymes. The distribution of fatty acids in the phosphatidylethanolamine molecule was not correlated simply with the specificities of these enzymes, but the relatively high specificity for palmitoyl-CoA of the glycerophosphate acyltransferase system to form 2-acyl-glycerophosphate, followed the relatively high specificity for oleoyl-CoA of the 2-acyl-glycerophosphate acyltransferase system, provided a basis for producing the major molecular species of phosphatidylglycerol.

Positional distribution of fatty acids in cardiolipin of mitochondria from 21-day-old rats.

Pure cardiolipins (1,3-diphosphatidylglycerol) were prepared from mitochondria of heart, liver and kidney from 21-day-old male Wistar rats and submitted to Naja naja venom phospholipase A2 (EC 3.1.1.4) action. Incubation conditions were controlled carefully, and a complete hydrolysis of cardiolipin to lysocardiolipin (di [1 (1'') acyl sn-glycero-3-phosphoryl] 1',3'-sn-glycerol) and fatty acids from positions 2(2'') was obtained in less than two hr practically without side reactions. Cardiolipins from the three organs contained low levels of saturated fatty acids; stearic acid accounted for 0.4-0.7% and palmitic acid for 1.4-3.5% of total fatty acids. These percentages apparently depended on the organ. In all three cases, linoleic acid was the major component, but its percentage varied from 62-78% of total fatty acids. Acyl chains linked to positions 1 (1'') of all three cardiolipin preparations exhibited a similar pattern: they were composed of linoleic acid for 85-89%. This fatty acid also was the main component esterified at position 2 (2''), but its percentage was much more variable: from 39.8% in heart to 51.2% in kidney and 67.8% in liver mitochondria. The remaining acids comprised octadecenoic and polyunsaturated fatty acids with more than 18 carbon atoms in different proportions. As opposed to other phospholipids, cis-vaccenic acid, and not oleic acid, was the main octadecenoic acid present in cardiolipins. Octadecenoic acids were nine- to 10-fold more concentrated at positions 2 (2'') than at positions 1 (1''). The percentage of cis-vaccenic acid was four- to five-fold higher than that of oleic acid at positions 2 (2''), whereas oleic acid dominated at positions 1 (1'').(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of positional distribution of fatty acids in palm oil by13C NMR spectroscopy

AbstractThe13C NMR spectrum of the carbonyl carbons of the acyl groups of triacylglycerols of palm oil has been shown to give the composition of saturated, oleic and linoleic acyl groups at the 1,3‐positions and at the 2‐position of the glycerol moiety. Except for the lack of differentiation of the saturated fatty acids, the13C NMR technique provides the same information as the tedious enzymatic hydrolysis cum fatty acid analysis. The carbonyl carbon of the linolenic acyl group (18∶3,[cis, cis, cis]‐9, 12, 15) has a chemical shift which is only 0.005 ppm to low frequency of that of the linoleic acyl group (18∶2,[cis, cis]‐9, 12), so that the two resonances may not be distinguishable (or resolved) even at a high magnetic field.

Biosynthesis of sulfoquinovosyldiacylglycerol in higher plants: The origin of the diacylglycerol moiety

The positional distribution of fatty acids in chloroplast polar lipids and phosphatidylcholine from leaves of four plants has been measured in order to determine the origin of the diacylglycerol (DAG) moieties of each lipid. In spinach and tobacco, the DAG of sulfoquinovosyldiacylglycerol (SQDG), monogalactosyldiacylglycerol (MGDG), and digalactosylglycerol (DGDG) were derived partly from the chloroplast and partly from the cytoplasm. The contribution of the chloroplast pathway differed for each lipid, but in both plants the proportion of a lipid derived from that pathway was in the order SQDG > MGDG > DGDG. In contrast, all the DAG moieties of the three glycolipids of wheat and cucumber were derived from the cytoplasm. The DAG moiety of chloroplast phosphatidylglycerol was synthesized in the chloroplast in all four plants.

The mechanism of membrane response to chilling. Effect of temperature on phospholipid deacylation and reacylation reactions in the cell surface membrane.

The ciliary membrane of Tetrahymena pyriformis is physically and metabolically remote from the main centers of lipid metabolism. Nevertheless, it possesses an independent capacity to modify its phospholipid molecular species composition rapidly under stress. The role of ciliary phospholipid deacylating and reacylating enzymes in this phenomenon has been evaluated. Isolated cilia showed substantial phospholipase A (combined A1 and A2), acyl-CoA synthetase and acyltransferase activities. Activities of all the three enzymes of cilia from 39 degrees C-grown cells were greatly reduced when the cilia were incubated at 15 degrees C. In contrast, the phospholipase A and acyltransferase activities in cilia from 15 degrees C-grown cells were surprisingly high at 15 degrees C and twice as high at 37 degrees C as were the equivalent activities in preparations from 39 degrees C-grown cells. While the in vivo substrate specificity of phospholipase A could not be meaningfully assessed, the acyltransferases exhibited a temperature-dependent substrate specificity in vivo. Growth temperature also affected the positional distribution of fatty acids incorporated into ciliary phospholipids in vivo. The ability of acyltransferases to utilize added [14C] acyl-CoA could be markedly stimulated, and their lipid class specificity could be significantly altered in vitro by supplementing the incubation mixture with exogenous lysophospholipid acceptors. These findings suggest that the rate-limiting factor in acyl chain turnover is not the activity of acyltransferases per se but rather the availability of suitable substrates and acceptors. Therefore, we postulate that temperature alters the rate and specificity of ciliary membrane phospholipid retailoring primarily by controlling the in situ phospholipase A activity.

Temperature-Dependent Phase Behavior of Phosphatidylglycerols from Chilling-Sensitive and Chilling-Resistant Plants

Seven major lipid classes were isolated from leaves of chilling-sensitive and chilling-resistant plants, and the temperature-dependent phase behaviors of their aqueous dispersions were studied by a fluorescence polarization method using trans-parinaric acid and its methyl ester. Phosphatidylglycerols from the chilling-sensitive plants went from the liquid crystalline state into the phase separation state at about 30 degrees C in 100 mm NaCl and at about 40 degrees C in 5 mm MgCl(2). In contrast, phosphatidylglycerols from the chilling-resistant plants went into the phase separation state at a much lower temperature. The other classes of lipids remained in the liquid crystalline state at all temperatures between 5 degrees C and 40 degrees C regardless of the chilling sensitivity of the plants, except sulfoquinovosyl diacylglycerol from sponge cucumber in which phase separation seemed to begin at about 15 degrees C. Compositions and positional distributions of fatty acids of the lipids suggest that the phosphatidylglycerols from the chilling-sensitive plants, but no other lipids, contained large proportions of molecular species which undergo phase transition at room temperature or above. The thermotropic phase behaviors and the fatty acid compositions suggest that, among the major lipid classes from leaves of the chilling-sensitive plants, only phosphatidylglycerol can induce a phase transition. Since a major part of this lipid in leaves originates from the chloroplasts, phase transition probably occurs in the chloroplast membranes.

An enzymatic rationale for the randomization of the positional distribution of fatty acids in phospholipids of ascites hepatoma AH 130

Fatty acids present in glycerophospholipids isolated from Yoshida ascites hepatoma AH 130 are more randomly distributed among the 1- and 2-positions than are fatty acids of normal liver phospholipids. The relative abundance of unsaturated fatty acids at the 1-position was ascribed to the lower palmitate-specific glycerophosphate acyltransferase activity in mitochondria of the hepatoma cells, an observation supporting the conclusion put forward for the similar randomization observed in Ehrlich ascites cells (Haldar D., Tso, W.-W. and Pullman M.E. (1979) J. Biol. Chem. 254, 4502–4509). The relative abundance of saturated fatty acids at the 2-position could be ascribed to the relatively lower acyl-CoA:l-acyl-glycerophosphocholine acyltransferase activity and to the change in the selectivity of the hepatoma acyl-CoA:l-acyl-glycerophosphate acyltransferase system into the lung type. The relatively lower selectivity for arachidonoyl-CoA as compared with oleoyl-CoA of the 1-acyl-glycerophosphocholine acyltransferase system is consistent with the decrease in polyenoic fatty acid content at the 2-position of the hepatoma phospholipids.

A comparison of the positional distribution of fatty acids in milk triglycerides of the extant monotremes platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus).

Milk triglycerides from the platypus were subjected to fatty acid and stereospecific analysis to determine the positional distribution of fatty acids in the triglycerides. Of the major fatty acids, 12∶0 was preferentially esterified at thesn-3 position, 14∶0 and 16∶0 were selectively associated with thesn-2 position, and 18∶0 was located predominantly at thesn-1 position. The unsaturated fatty acids, 14∶1, 16∶1, 18∶1, 18∶2 and 18∶3, were preferentially esterified at thesn-3 position. The fatty acid distribution pattern of the platypus, a monotreme, is similar to that of marsupials and eutherians but is in contrast to the only other extant monotreme, the echidna.

Altered acyltransferase activity in Escherichia coli associated with mutations in acyl coenzyme A synthetase.

Growth of a temperature-sensitive general fatty acid synthesis mutant of Escherichia coli K12 at its restrictive temperature in the presence of exogenous palmitate results in lysis of the bacterium. Under these conditions, palmitate is incorporated into membrane phospholipid to a high level. Mutants of bacteria restricting this incorporation (having a palmitate-resistant phenotype) have been isolated and one such mutant, strain L8-2/3, has been further characterized. This mutant has lowered acyl-CoA synthetase (fadD) activity (25-33% of normal) and consequently is defective in fatty acid uptake. This lowered uptake could explain the palmitate-resistant phenotype of strain L8-2/3. However, both in vivo (fatty acid composition and positional distribution data) and in vitro (acyltransferase activity measurements) experiments suggest that this mutant is also altered in its acyltransferase activities. The mutation(s) of strain L8-2/3 appears to allow increased (approximately 2-fold) incorporation of myristate (and possible unsaturated fatty acids) into position 2 of 1-acyl-sn-glycerol 3-phosphate but normal palmitate incorporation into the same position. The incorporation of palmitate, myristate, and oleate into position 1 of sn-glycerol 3-phosphate by strain L8-2/3 is also higher than that observed with the parent, strain L8-2. Replacing the partially defective fadD gene of strain L8-2/3 with a wild type allele conferred on this strain the palmitate sensitivity and the acyltransferase activity of the parent strain L8-2. This finding, taken together with other data, suggests that acyl-CoA synthetase interacts with the acyltransferase(s) in some manner to influence the fatty acid specificity of the acyltransferase.

Fatty acid positional distribution in phospholipids of a psychrophilic bacterium during changes in growth temperature

The major phospholipids of the psychrophilic bacteriumMicrococcus cryophilus, phosphatidylethanolamine and phosphatidylglycerol, have similar fatty acid compositions, comprising almost entirely palmitoleic and oleic acids. We show that there is a preference for the longer chains in thesn-1 position of both phosphatidylethanolamine and phosphatidylglycerol, both during isothermal growth and after temperature shifts, despite the fact that the overall phospholipid C18/C16 acyl chain ratio decreases with a lowering of growth temperature. Although it has been shown using model systems that the isomeric configurationsn-1-long,sn-2-short lowers lipid melting temperature, this paper reports the first clear-cut demonstration of such an isomeric preference in a natural system. We discuss how this acyl chain configuration contributes to membrane fluidity inM. cryophilus, in terms of adaptation to its psychrophilic habitat.

Modification of positional distribution of fatty acids in phosphatidylinositol of rabbit neutrophils stimulated with formylmethionyl-leucyl-phenylalanine

The effects of formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe) on the positional distribution of fatty acids in phosphatidylinositol (PI), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were investigated with rabbit neutrophils. The proportion of arachidonate at the C-2 position of PI was 35.0% in resting neutrophils and declined to 30.8% after 5 min stimulation with the peptide at a concentration of 10 −7 M. In contrast, the profiles of the positional distribution of fatty acids in PC and PE were not affected upon stimulation with fMet-Leu-Phe. The phospholipid composition of rabbit neutrophils was examined at different time intervals following the addition of fMet-Leu-Phe. PI and PC, but no other phospholipids, exhibited significant changes in their quantities. The quantity of PC decreased at 5 min with a concurrent increase in that of lysophosphatidylcholine (lysoPC), suggesting a phospholipase A 2 action on PC. The quantity of PI, on the other hand, decreased at l min with an accompanying increase in phosphatidic acid when the profile of the positional distribution of fatty acids in PI remained unchanged. No lysophosphatidylinositol (lysoPI) was detected. This indicates the enhancement of the PI cycle in the fMet-Leu-Phe-stimulated neutrophils. The augmented PI cycle in response to fMet-Leu-Phe was further supported by the finding that [ 3H]arachidonyl-diacylglycerol and -phosphatidic acid accumulated at the expense of [ 3H]arachidonylPI in rabbit neutrophils prelabelled with pHlarachidonate. Restoration of the content of PI to the higher than the original level at 5 min after stimulation with fMet-Leu-Phe, however, leads to the suggestion that de novo synthesis of PI as well as PI resynthesis along the closed cycle of PI has occurred at 5 min and that this newly synthesized PI, via a de novo pathway with a different pattern of the positional fatty acyl composition, is the cause of the decreased proportion of arachidonate.

Positional Distribution of Fatty Acids in Triglycerides from Prepartum Mammary Gland Secretion and Early Postpartum Milk

Triglycerides from mammary gland secretion collected at 24, 17, 10, 7, and 3.5 days prepartum and from milk collected at 0 (2h), 1, 2, 3, 4, 5, 6, 7, 14, 21, and 28 days postpartum were subjected to fatty acid and stereospecific analysis. Prepartum mammary gland secretion differed from normal milk in that it contained approximately twice the amount of 16:0 and larger than normal amounts of 14:0. This was compensated for by less amounts of other medium-chain, short-chain, 18:0, and 18:1 acids. Positional distribution of fatty acids in milk from 1 day postpartum onward generally followed the specific pattern normally encountered for milk triglycerides. With exception of the first sample at 24 days prepartum, mammary gland secretion had medium-chain acids at 8:0, 10:0, 12:0, and sometimes 14:0 preferentially esterified at the sn-3-position rather than the sn-2-position. Relationships were linear between content of fatty acids at the three stereo-specific positions and content of the same acid in triglycerides. These significant relationships are represented by regression equations. With varying triglyceride fatty acid content, fatty acid content at the three positions did not change at the same rate.

Compositions and Positional Distributions of Fatty Acids in Phospholipids from Leaves of Chilling-Sensitive and Chilling-Resistant Plants

The compositions and positional distributions of fatty acids in the major leafphospholipids of phosphatidylg lycerol, phosphatidylcholine and phosphatidylethanolamine were analyzed by gas-liquid chromatography and enzymic hydrolysis, and chilling-sensitive and chilling-resistant plants were compared with respect to the relative contents of palmitic and (ranj-jd3-hexadecenoic acids in the separated phospholipids. A distinct difference between these plants was found in the fatty acid compositions of phosphatidylglycerol, in which the sum of palmitic and trans-A 3-hexadecenoic acids ranged from 60 to 78% of the total fatty acids in 8 species of chilling-sensitive plants, and from 50 to 57% in 11 species of chilling-resistant plants. The only exception among the chillingsensitive plants in this respect was the tomato, in which the sum of palmitic and trans^]3-hexadecenoic acids in phosphatidylglycerol amounted to 54%. The fatty acid compositions and the positional distributions of fatty acids in phosphatidylg lycerol suggest that the occurrence of high proportions of dipalmitoyl and l-palmitoyl-2-((raRi-/J3hexadecenoyl) species in this lipid is correlated with the susceptibility to chilling of the leaves of higher plants. In the compositions and positional distributions of fatty acids in phosphatidylcholine and phosphatidylethanolamine, no difference was found between the chilling-sensitive and chilling-resistant plants.

Positional distribution of fatty acids in the triglyceride classes of milk fat.

A sample of milk fat was fractionated into high, medium and low molecular weight triglycerides by silicic acid column chromatography. Each fraction was further separated by silver ion adsorption thin-layer chromatography into triglyceride class which were subjected to stereospecific analysis. Trans-monoene fatty acids were incorporated into triglycerides in the same manner as their cis-isomer. The specific positional distribution for fatty acids in intact mild fat triglycerides was not always maintained in the molecular weight fractions or in the various classes of unsaturation. The significance of these findings is discussed in relation to biosynthetic mechanisms for milk fat synthesis.

Structures of the triglycerides of cows' milk, fortified milks (including. infant formulae), and human milk

The positional distributions of fatty acids in triglycerides from cows' milk, cows' milk enriched in linoleic acid by dietary means, and two commercial infant formulae fortified with vegetable fats have been determined for comparison with human milk. The results are discussed in terms of the digestibility of the fats and of the requirements of the human infant for linoleic acid.

Reversible thrombin-induced modification of positional distribution of fatty acids in platelet phospholipids: Involvement of deacylation-reacylation

The positional distribution of fatty acids in phospholipids was analyzed for human platelet activated by thrombin. At 30 sec after thrombin-activation, when the content of phosphatidylinositol(PI) fell transiently, the 2-position of PI underwent a significant decrease in arachidonate (77.6% → 61.5%) with a compensating increase in oleate and stearate. However, accompanying PI resynthesis, its positional distribution tended to revert to that of non-activated platelets. There was no significant change in the fatty acyl positioning in other phospholipids. In addition, evidence is presented that human platelet lysates acylate 1-acyl- sn-glycero-3-phosphorylinositol and the acylation rate for arachidonate was 2.5 times higher than for any other unsaturated fatty acids tested. These data indicate that the thrombin-induced alteration in fatty acid pairing of PI is ameliorated by the deacylation-reacylation follwing PI resynthesis.

Studies on thermal adaptation in tetrahymena membrane lipids changes in positional distribution of fatty acids in diacyl-phospholipids and alkyl-acyl-phospholipids during temperature acclimation

The positioning of acyl chains in both 1- O- alkyl-2- acyl- and 1,2-diacyl-phospholipids was analyzed at various time intervals for a thermotolerant strain (NT-1) of Tetrahymena pyriformis cells during cold acclimation. During the 10 h period of adaptation, cells were not able to grow but maintained the ability to divide. The content of palmitate (16 : 0) in phosphatidylcholine and phosphatidylethanolamine was decreased after temperature-shift, with a concurrent increase of palmitoleate (16 : 1 Δ9) and γ-linolenate (18 : 3 Δ6,9,12). An increase in γ-linolenate at the 1-position and linoleate at the 2-position was observed in diacyl-phospholipids (phosphatidylethanolamine, phosphatidylcholine and 2-aminoethylphosphonolipid). The 2-position of 1- O- alkyl-2- acyl- phosphatidylcholine, and 1- O- alkyl-2- acyl-(2-aminoethyl)phosphonolipid was occupied mainly by γ-linolenate together with cilienate (18 : 2 Δ6,11) and linoleate (18 : 2 Δ9,12). Cilienate and γ-linolenate at the 2-position of 1- O- alkyl-2- acyl-phosphatidylcholine were increased after temperature shift, with a small decrease of linoleate. There are little significant changes in alkyl ether lipid content of phosphatidylcholine and 2-aminoethylphosphonolipid after temperature shift. The results indicate that phosphatidylethanolamine, which is most abundant and present only in the diacyl form, would play a crucial role in thermal adaptation of membrane lipids, by replacing palmitate with γ-linolenate at its 1-position, and also that hexadecyl/γ-linolenoyl phosphatidylcholine would be an important molecular species in the acclimation.

Effect of different levels of dietary fats upon the positional distribution of fatty acids in rat body triacylglycerols

1. 1. The main purpose of the study was to describe and to compare the effect of different dietary fatty acids introduced at different levels into the diet on the positional distribution of fatty acids in rat body triacylglycerols. Only distribution between sn-2 (internal) and sn-1 + sn-3 (external) positions was considered in this study. 2. 2. The positional distribution of fatty acids was first determined for controls fed on a low fat diet (1% D.M.). The same study was then carried out with 11 different dietary treatments and results were systematically compared with controls. The effects of four main molecules were tested: linoleic acid, oleic acid, lauric acid and capric acid. 3. 3. Different alterations of the positional distribution of fatty acids in body triacylglycerols were obtained. They are graphically described and discussed.

Characterization of the Constituent Fatty Acids in the Phosphoglycerides of Chemically Induced Polycystic Disease and Gastric Tumor in Rat.

The positional distribution of fatty acids in choline- and ethanolamine phosphoglycerides from the livers of polycystic disease-bearing rats and stomachs of gastric tumor-bearing rats was analyzed and compared to that in normal rat liver and stomach. Polycystic disease and gastric tumors were induced with N-Methyl-N'-Nitro-N-Nitrosoguanidine. There was no significant difference between diseased and normal organs with respect to the composition of fatty acids at the 1-position, except that diseased livers exhibited an increase of approximately 22% in 16: 0 fatty acid and a decrease of approximately 12% in 18: 1 fatty acid. However, in diseased organs, there were marked quantitative changes in the positional distribution of fatty acids at the 2-position, their composition exhibiting greater saturation. Furthermore, in diseased organs, there was an increase in 15: 0 fatty acid at the 2-position of ethanolamine phosphoglycerides.

The positional distribution of fatty acids in Escherichia coli phospholipids is not regulated by sn-glycerol 3-phosphate levels.

Large changes in the intracellular concentration of sn-glycerol 3-phosphate had no effect on the acyl chain distribution of the phospholipids of Escherichia coli. This result directly contradicts the prediction by other workers based on in vitro experiments.