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PubMed1986

Fatty acid composition of leaf lipids determined after combined digestion and fatty acid methyl ester formation from fresh tissue.

A procedure which uses hot methanolic HCl to digest fresh tissue and simultaneously convert the fatty acids of the leaf lipids to the corresponding methyl esters is described. Extraction of the fatty acid methyl esters into a small volume (0.3 ml) of hexane means that a sample for GLC analysis can be taken directly from the tube used for the digestion/methylation reaction. The procedure provides a fatty acid analysis which is comparable to that obtained by a more conventional technique involving separate extraction, saponification, and methylation steps, but the overall yield is reduced by 10-20%. The analysis can be made quantitative by including an internal standard with the tissue sample.

Chromatography, Gas↗
PubMed1990

Dietary trans fatty acids modulate erythrocyte membrane fatty acyl composition and insulin binding in monkeys.

The substitution of trans- for half of the cis-monounsaturated fatty acids in the diet of Macaca fasicularis monkeys resulted in alterations in erythrocyte fatty acid composition and insulin receptor properties but not in membrane fluidity. Both cis and trans diets contained 10% fat and similar fatty acid compositions, except that approximately 50% of the cis-octadecenoate (c-18:1) in the cis diet was replaced with trans-octadecenoate isomers (t-18:1) in the trans diet. Compared with the cis diet, the trans diet resulted in the incorporation of approximately 11% t-18:1, an approximately 50% decrease in c-18:1, an approximately 16% decrease in total saturated fatty acids, and an approximately 20% increase in 18:2(n-6) in erythrocyte membrane lipids. The increase in 18:2(n-6) may reflect on homeostatic mechanisms designed to maintain overall membrane fluidity, as no diet-related changes in fluidity were observed with diphenylhexatriene steady state fluorescence polarization. Values observed for insulin binding and insulin receptor number were higher and binding affinity was lower in monkeys fed the cis diet. In the absence of an effect on overall membrane fluidity, altered receptor activity suggests that insulin receptor activity is dynamic, requiring specific fluid membrane subdomains or highly specific fatty acid-protein interactions.

Journal Article↗
PubMed1985

Purification and spectroscopic properties of pyrene fatty acids.

Pyrene fatty acids are routinely purified by silica based column chromatography and analyzed on thin-layer silica plates (H.-J. Galla et al., Chem. Phys. Lipids, 23 (1979) 239-251). Although pyrene decanoic acid runs as a single spot on thin-layer chromatography (TLC), gas-liquid chromatography (GC) of the methyl ester derivatives of a representative sample revealed four separate peaks with the major component only 92% of the total. High performance reverse phase liquid chromatography (HPLC) was used to purify pyrene decanoic acid and separate the contaminants. After two passes on a C18 reverse phase HPLC column, pyrene decanoic acid is 99.98% pure by GC analysis. Absorption, fluorescence, and NMR spectra were recorded for pyrene decanoic acid and the major impurities. The results indicate that one impurity is a C10 fatty acid with an altered aromatic moiety. Two other impurities are pyrene derivatives but their acyl chains probably are not decanoic acid.

Chromatography, Gas↗
PubMed1994

Effects of ursodeoxycholic acid treatment on essential fatty acid deficiency in patients with biliary atresia.

To assess whether ursodeoxycholic acid (UDCA) treatment has any beneficial effect on essential fatty acid (EFA) deficiency in patients who have had a Kasai operation for extrahepatic atresia (EBA), responses of serum fatty acids to UDCA administration (15 mg/kg/d) were investigated in eight jaundice-free patients and in eight patients with jaundice (serum total bilirubin > or = 1.0 mg/dL). All patients were also given taurine supplementation (100 mg/kg/d). Serum fatty acid composition was determined before and 6 months after UDCA treatment. Serum total bile acid concentration and serum total bilirubin value, as a part of conventional liver function tests, were measured before and during UDCA therapy. Before UDCA treatment, the concentrations of linoleic acid and arachidonic acid were significantly lower (P > .05 for the former; P > .01 for the latter) in both the jaundice and jaundice-free groups than in the controls. After 6 months of treatment, the linoleic acid concentration significantly increased (P > .05), to the normal range, in the jaundice-free group, but not in the jaundice group. The arachidonic acid concentration did not increase significantly in either group. The serum total bile acid concentration was lower in six of the eight jaundice-free patients and in four of the eight jaundice patients. The serum total bilirubin value decreased in six of the eight jaundice-free patients and in four of the eight jaundice patients; however, the degree of improvement was not statistically significant in either group. No side effects developed, and there were no changes in blood chemistry values unrelated to liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic Acid↗
PubMed1996

Thermodynamic and kinetic properties of fatty acid interactions with rat liver fatty acid-binding protein.

Fatty acid-binding protein from rat liver (L-FABP) binds 2 fatty acids (FA) per protein, in contrast to FABPs from adipocyte, heart, and intestine, for which binding and structural studies are consistent with a single FA binding site. To understand better the unique characteristics of L-FABP, we have carried out equilibrium binding and kinetic measurements of long chain FA using the fluorescent probes of free fatty acids (FFA), ADIFAB and ADIFAB2, to monitor the concentration of FFA in the reaction of FA with L-FABP. We found that the dissociation constants (Kd) ranged from about 1 nM to 4 microM, being largest for myristate at 45 degrees C and smallest for oleate at 10 degrees C, and that 2 FA were bound per L-FABP for all temperatures and FA. The binding measurements also revealed that at temperatures below 37 degrees C, affinities for the two binding sites differ by between 5- and 20-fold but as the temperature was increased, the affinities converge toward equal values. Off-rate constants (koff) were similar for all FA and for temperatures between 10 and 45 degrees C, ranged from about 0.1 s-1 to 50 s-1. Moreover, for all FA, koff values for dissociation from both the high and low affinity sites were similar, indicating that binding affinity differences at the lower temperatures reflect lower on-rates for binding to the low affinity site. The temperature at which the affinities of the two sites become equivalent depends upon the FA; higher temperatures (45-50 degrees C) are required for the unsaturated FA and myristate than for the longer chain saturated FA (<37 degrees C). This transition from different to equivalent affinity binding sites at specific temperatures reflects a nonlinear van't Hoff behavior of the high affinity site, which in turn is a reflection of large heat capacity changes (between -0.6 and -1.2 kcal K-1 mol-1) that accompany FA binding to the high affinity site. These heat capacity changes, which are unique to L-FABP, do not appear to be correlated with a significant conformational change upon ligand binding. The differences between long chain saturated and unsaturated FA suggest that the conformation of FA bound to L-FABP may differ with both FA type and temperature, and that, in comparison to other FABPs, L-FABP may have distinctly different effects on saturated and unsaturated FA metabolism.

Animals↗
PubMed1985

Bovine fatty acid binding proteins. Isolation and characterisation of two cardiac fatty acid binding proteins that are distinct from corresponding hepatic proteins.

When a 100,000 X g supernatant from bovine heart was incubated with [1-14C]oleic acid and subjected to isoelectric focusing, two fatty acid binding proteins (FABPs) with isoelectric points at 4.9 and 5.1 were detected. The proteins were purified on a large scale first by heat and acid precipitation of a postmitochondrial supernatant, as well as fractionation with ammonium sulfate, then by alternate application of ion-exchange and gel chromatography. The procedure afforded around 60 mg pure proteins from 1.5 kg fresh heart muscle. Relative molecular masses of 15 300 +/- 1600 for both proteins were derived from sodium dodecyl sulfate/polyacrylamide gel electrophoresis, gel chromatography, sedimentation velocity as well as from amino acid analysis. Up to 50% of the proteins' secondary structures consisted of beta-sheet. N-termini of the peptide chains were blocked; the amino acid compositions of the two proteins were similar, but differed considerably from those of the two FABPs isolated from bovine liver [Haunerland et al. (1984) Hoppe Seyler's Z. Physiol. Chem. 365, 365-376]. Whereas hepatic FABPs changed their pI upon binding fatty acids, cardiac FABPs did not. Cardiac FABPs were immunologically identical, but did not cross-react with hepatic proteins. A reversible, concentration-dependent self-association reported for FABP from pig heart [Fournier et al. (1983) Biochemistry 22, 1863-1872] was not observed for FABP from bovine heart. Changes of concentration did not alter secondary structure, intrinsic fluorescence or the sedimentation coefficient of the protein.

Amino Acids↗
PubMedDate not supplied

Is fatty acid uptake in cardiomyocytes determined by physicochemical fatty acid partition between albumin and membranes?

Palmitate uptake by isolated, calcium-resistant cardiomyocytes was measured by using a stimulation chamber in which cell contraction can be evoked electrically. Experiments were performed in a medium containing physiological interstitial concentration of albumin (2%) and palmitate/albumin (P/A) ratios ranging from 0.03 to 2.5, and were compared to experiments with fixed P/A ratio (= 1). Initial rate of uptake (Vi) was calculated from fitted uptake vs. time curves as measured by accumulation of radioactivity in the cells from 14C-labelled palmitate. Vi-vs.-concentration curves exhibited a saturable component, if albumin concentration was kept constant. Almost no change in Vi was observed in experiments performed at constant P/A. This is in contrast to the albumin receptor hypothesis. The 14C-palmitate content of the myocytes as estimated by thin-layer-chromatography did reach a plateau at less than or equal to 30s and had the same value at 30 min after administration. The cellular content of labelled palmitate could be attributed to the membrane compartment as calculated from partition coefficient (Kc) of fatty acids (FA) between albumin and membranes. With electrical stimulation Vi-vs.-palmitate concentration kinetics showed a shift in apparent Km from 62 microM (P/A = 0.22) to 23 microM (P/A = 0.08), and presence of 2,4-dinitrophenol increases Vi. Our results suggest that FA-transfer across the sarcolemmal membranes is determined by a physicochemical equilibrium between the compartments of extracellular FA-albumin complex, the membrane lipid phase, intracellular FA binding proteins and the respective aqueous phases.(ABSTRACT TRUNCATED AT 250 WORDS)

2,4-Dinitrophenol↗
PubMed1978

Synthesis of chloromethyl ketone derivatives of fatty acids. Their use as specific inhibitors of acetoacetyl-coenzyme A thiolase, cholesterol biosynthesis and fatty acid synthesis.

A general route for the synthesis of chloromethyl ketone derivatives of fatty acids is described. 5-Chloro-4-oxopentanoic acid, 7-chloro-6-oxoheptanoic acid, 9-chloro-8-oxononanoic acid and 11-chloro-10-oxoundecanoic acid were synthesized by this method and tested as covalent inhibitors of pig heart acetoacetyl-CoA thiolase. The K1 decreased by approx. 20-fold for each pair of methylenes added to the chain length, showing that the initial stage in inhibitor binding occurs at a non-polar region of the protein. This region is probably located at the enzyme active site, since inhibition was prevented by acetoacetyl-CoA or acetyl-CoA but not by CoA. The site of modification by chloromethyl ketone derivatives of fatty acids is restricted to a thiol group, since inactivation of the enzyme was prevented by reversible thiomethylation of the active-site thiol. In contrast, an amino-directed reagent, citraconic anhydride, still inactivated the enzyme, even when the active-site thiol was protected. Evidence that the enzyme thiol was particularly reactive came from studies on the pH-dependence of the alkylation reaction and thiol-competition experiments. Inhibition of the enzyme proceeded suprisingly well at acidic pH values and a 10(5) molar excess of external thiol over active-site thiol was required to prevent inhibition by 0.3 mM-9-chloro-8-oxononanoic acid. In addition to inhibiting isolated acetoacetyl-CoA thiolase, in hepatocytes the chloromethyl ketone derivatives of fatty acids also inhibited chloresterol synthesis, which uses this enzyme as an early step in the biosynthetic pathway. In isolated cells, the chloromethyl ketone derivatives of fatty acids were considerably less specific in their inhibitory action compared with 3-acetylenic derivatives of fatty acids, which act as suicide inhibitors of acetoacetyl-CoA thiolase. However, 9-chloro-8-oxononanoic acid was also an effective inhibitor of both hepatic cholesterol and fatty acid synthesis in mice in vivo, whereas the acetylenic fatty acid derivative, dec-3-ynoic acid, was completely ineffective. The effective inhibitory dose of 9-chloro-8-oxononanoic acid (2.5-5 mg/kg) was substantially lower than the estimated LD50 for the inhibitor (100 mg/kg).

Acetyl-CoA C-Acetyltransferase↗
PubMed1984

Determination of C20-C30 fatty acids by reversed-phase chromatographic techniques: an efficient method to quantitate minor fatty acids in serum of patients with adrenoleukodystrophy.

An analytical method for the determination of saturated very long chain (VLC) fatty acids in the serum has been devised. Free fatty acids obtained after hydrolysis of total lipid extracts were converted into p-bromophenacyl esters. The derivatives were purified in two sequential steps by clean-up on C18 reversed-phase cartridge and fractionation by reversed-phase thin-layer chromatography (TLC), and then quantitated by high performance liquid chromatography (HPLC) analysis. This technique provides a reliable and alternative method for the biochemical identification of patients and carriers of an inherited metabolic disease characterized by the accumulation of saturated VLC fatty acids (C24-C26) such as Adrenoleukodystrophy (ALD). In four cases of diagnosed ALD the fatty acid composition of serum total lipids was dramatically enriched in saturated VLC fatty acids compared to controls. The ratio of hexacosanoic acid (C26:0) to docosanoic acid (C22:0) in ALD patients was approximately six-fold higher than that of healthy controls or patients affected by metabolic or neurological disorders other than ALD.

Adrenoleukodystrophy↗
PubMed1989

Capillary gas chromatographic analysis of mycolic acid cleavage products, cellular fatty acids, and alcohols of Mycobacterium xenopi.

The fatty acids, alcohols, and mycolic acids of 26 strains of Mycobacterium xenopi were studied by capillary gas chromatography and thin-layer chromatography. All strains contained alpha-, keto-, and omega-carboxymycolates. The primary mycolic acid cleavage product was hexacosanoic acid. The fatty acid patterns and, especially, the presence of 2-docosanol are characteristic markers of M. xenopi.

Alcohols↗
PubMed2002

Resonant electron capture mass spectrometry of free fatty acids: examination of ion structures using deuterium-labeled fatty acids and collisional activation.

The structures of [M-H](-) ions generated from free fatty acids in resonant electron capture at energies of 1.2 and 7.2 eV were investigated using deuterium-labeled isotopomers and collision-induced dissociation. The [M-H](- small middle dot) ions occur in both a carboxylate anion and a carbanion form. While the formation of the carboxylate anion at 1.2 eV involves the loss of a carboxylic hydrogen, that at 7.2 eV involves the loss of a hydrogen from different positions in the aliphatic chain followed by a rearrangement of a carboxylic hydrogen on to the radical site in the chain. The [M-H-H(2)O](-) ion which is a minor ion in the resonant electron capture spectrum at 7.2 eV is shown to be a precursor for the charge-remote fragment ions corresponding to formal losses of a hydrogen and elements of alkanes. The [M-H-H(2)O](-) ion corresponding to the second major ion in the resonant electron capture spectrum at 7.2 eV is demonstrated to be consistent with a cyclopentanone anion structure. On the basis of new insights obtained in the present study and taking into account previous results, an updated proposal is presented for the mechanism of charge-remote fragmentation which operates in resonant electron capture of free fatty acids at 7.2 eV.

Deuterium↗
PubMed1998

Fatty acid balance studies in preterm infants fed formula milk containing long-chain polyunsaturated fatty acids (LCP) II.

A milk formula (Prematil-LCP) containing long-chain polyunsaturated fatty acids (LCP) and with a fatty acid profile closely resembling breast milk has recently been introduced for preterm infants. A double-blind randomized controlled trial was performed comparing fatty acid absorption from Prematil-LCP (n=10) and standard Prematil (n=10). Formula-fed preterm infants underwent 3 d fat balances (once full enteral feeds were established) along with a parallel human milk fed group (n=11). Plasma samples were taken on the last day. Median total fat excretion (absorption, %) was 2.34g kg(-1) (82.0), 2.64g kg(-1) (82.9) and 1.65g kg(-1) (87.8) with Prematil, Prematil-LCP and human milk feeding, respectively. This reflected differences in the excretion and absorption of long-chain saturated fatty acids. All groups excreted detectable LCP. LCP disappearance was higher in infants fed human milk than in those fed Prematil-LCP, particularly for n-6 LCP (p < 0.01). Nevertheless, excreted LCP equated to < 30% dietary intake, with Prematil-LCP feeding. Plasma lipid fatty acid composition reflected differences in dietary LCP intake.

Analysis of Variance↗
PubMed1995

Interaction of N-(2-hydroxybenzyl)-omega-amino carbonic acids, novel amphipathic fatty acid derivatives, with membrane: partition coefficients.

The methods for partition coefficient (Kp) determination were developed for different concentrations of N-(2-hydroxybenzyl)-omega-amino carbonic acids, a new class of amphipathic fatty acid derivatives (An), their deutero (AnD) and bromine (AnBr) derivatives. To do this the following methods were used: 2H-NMR, equilibrium dialysis, centrifugation and fluorescence spectroscopy. Kp dependence on the An concentration is discussed. Kp values for AnBr were more than 120-times higher than those for An, the differences between them being smaller than those for the corresponding An. This series of new amphipathic compounds can be used as probes for membrane studies.

Bromine↗
PubMed1996

Supplementation with an algae source of docosahexaenoic acid increases (n-3) fatty acid status and alters selected risk factors for heart disease in vegetarian subjects.

The purpose of this double-blind study was to investigate the influence of dietary supplementation with an algae source of docosahexaenoic acid [DHA; 22:6(n-3)], devoid of any eicosapentaenoic acid [EPA; 20:5(n-3)], on serum/platelet DHA status, the estimated retroconversion of DHA to EPA, and risk factors for heart disease in vegetarian subjects. Healthy vegetarians (12 male, 12 female) consumed nine capsules daily of either DHA (1.62 g/d) or corn oil for 6 wk. Consumption of DHA capsules increased DHA levels in serum phospholipid by 246% (from 2.4 to 8.3 g/100 g fatty acids) and in platelet phospholipid by 225% (from 1.2 to 3.9 g/100 g fatty acids). EPA levels increased in serum phospholipid by 117% (from 0.57 to 1.3 g/100 g fatty acids) and in platelet phospholipid by 176% (0.21 to 0.58 g/100 g fatty acids) via metabolic retroconversion; the estimated extent of DHA retroconversion to EPA was 11.3 and 12.0%, based on the serum and platelet analyses, respectively. Arachidonic acid [AA; 20:4(n-6)] levels in serum and platelet phospholipids decreased moderately during the trial period (DHA group) as did both docosapentaenoic acids [22:5(n-6) and 22:5(n-3)]. Although no significant changes were found in the total and LDL-cholesterol levels with DHA supplementation, the total cholesterol:HDL-cholesterol ratio showed a moderate decrease over time as did the LDL-cholesterol:HDL-cholesterol ratio and serum triglyceride concentrations. DHA supplementation did not alter the various thrombogenic factors measured. In conclusion, DHA supplementation markedly enhanced the DHA status (of serum and platelets), provided for the formation of substantial EPA, and lowered the total and LDL-cholesterol:HDL-cholesterol ratios.

Adult↗
PubMed1992

Induction of enzymes involved in fatty acid beta-oxidation in Pseudomonas fragi B-0771 cells grown in media supplemented with fatty acid.

Induction of the enzymes involved in fatty acid beta-oxidation in Pseudomonas fragi B-0771 cells grown in a medium containing straight chain saturated fatty acids was studied. The acyl-CoA dehydrogenase (ACDH) activity was induced during the exponential phase in cells grown in palmitic acid-supplemented medium, reached a maximum at the early stationary phase, and then gradually decreased thereafter. Changes in the overall activities of 2-enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase, both existing on the multienzyme complex (HDT) involved in fatty acid beta-oxidation, were similar to that in ACDH activity. Straight chain saturated fatty acids having more than 6 carbon atoms could induce both the ACDH and HDT activities, and C13-C15 fatty acids caused the greatest induction of both activities. Changes in the overall activities of 2-enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase correlated with that in the amount of the alpha-subunit of HDT during the entire culture period in the medium containing palmitic acid. Surprisingly, the stoichiometry of the alpha- and beta-subunit proteins of HDT was not maintained into the stationary phase culture, though the genes encoding the alpha- and beta-subunits are tandemly coded in bacterial genomic DNA.

Acetyl-CoA C-Acyltransferase↗