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PubMed1977

Depletion of docosahexaenoic acid in retinal lipids of rats fed a linolenic acid-deficient, linoleic acid-containing diet.

Rats were raised for 2 generations on a diet in which 1.25% methyl linoleate was the only source of fat. Control rats were given 1.0% methyl linoleate plus 0.25% methyl linolenate. Lipids were extracted from retinas and their fatty acids were analyzed by gas-liquid chromatography. Docosahexaenoic acid accounted for 33.8% of total fatty acids in control retinas, for 13% of fatty acids in first-generation deficient retinas, and for 2.7% of fatty acids in second-generation deficient retinas.

Animals↗

PubMed1987

Effects of 2,4,5-trichlorophenoxyacetic acid and quinolinic acid on 5-hydroxy-3-indoleacetic acid transport by the rabbit choroid plexus: pharmacology and electron microscopic cytochemistry.

2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) reduced the uptake of 5-hydroxy-3-indoleacetic acid (5-HIAA) by the choroid plexus in a dose-related manner, while treatment with quinolinic acid at comparable concentrations did not inhibit 5-HIAA uptake. The role of carrier-mediated transport in the clearance of 5-HIAA from cerebrospinal fluid (CSF) was also evaluated in vivo by ventriculocisternal perfusion. Steady-state clearance of 5-HIAA from CSF exceeded that of inulin and was reduced competitively in the presence of 2,4,5-T. However, the clearance was not affected by quinolinic acid. The effect of 2,4,5-T on transport enzyme systems was also studied by electron microscopic cytochemistry. Na+-K+-ATPase and cytochrome oxidase activities in the choroid plexus were reduced by 2,4,5-T. Since this transport system in the choroid plexus is normally responsible for the excretion of the serotonin metabolite from the brain to the plasma, accumulation of endogenously produced organic acids in the CSF and the brain, secondary to reduced clearance by the choroid plexus, could be a contributing factor in the development of neurotoxicity.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed2004

Dynamical dimer structure and liquid structure of fatty acids in their binary liquid mixture: decanoic/octadecanoic acid and decanoic/dodecanoic acid systems.

Dimer structure and liquid structure of fatty acids in their binary mixtures such as decanoic acid (DA)/octadecanoic acid (SA) and DA/dodecanoic acid (LA) were studied through the measurements of self-diffusion coefficient (D), differential scanning calorimetry (DSC), density and viscosity. The obtained phase diagrams showed that DA and SA form a eutectic in the solid state but partly a solid solution in the SA-rich region; DA and LA form an incongruent-melting compound which forms a eutectic with DA. In the liquid mixture of DA and SA, the D of DA is larger than that of SA over the entire range of compositions and tends to approach the D of SA with increasing SA-mole fraction; the D of DA in the DA/LA system is also larger than that of LA especially in the LA-poor region and steeply approaches that of LA with increasing LA-mole fraction. These D values and phase diagrams were compared with those for the binary mixtures of n-alkanes (C14/C20, C19/C20 and C20/C24); it is concluded that the two kinds of fatty acids always form their individual homodimers in their liquid mixtures regardless of their compositions and temperatures.

Alkanes↗

PubMed2005

Incomplete replacement of docosahexaenoic acid by n-6 docosapentaenoic acid in the rat retina after an n-3 fatty acid deficient diet.

When sources of n-3 fatty acids are not present in the diet, nervous system docosahexaenoic acid (22:6n3) is replaced by docosapentaenoic acid (22:5n6). Dams were fed either an n-3 deficient diet or one containing alpha-linolenic acid (18:3n3) and 22:6n3 throughout pregnancy and lactation. Their male offspring at weaning also received either the n-3 deficient or n-3 adequate diets and were sacrificed at 5, 10, 20, 50 and 91 days of age. Retinal lipids were extracted and analysed by gas chromatography for fatty acyl content. The percentage of retinal 22:6n3 increased continuously over the 13 week course of the experiment but reached its maximal concentration around day 20. Non-reciprocal replacement of 22:6n3 by 22:5n6 was observed at postnatal day 20 and 50 but not at other time points. Complete replacement of 22:6n3 was apparent if elevations in both 22:5n6 and docosatetraenoic acid (22:4n6) were considered. These data indicate that during the rapid period of accretion of retinal 22:6n3 around postnatal day 20, the supply of 22:5n6 to the retina was inadequate to completely replace 22:6n3 in n-3 deficient rats.

Aging↗

PubMed1997

9-cis-retinoic acid enhances fatty acid-induced expression of the liver fatty acid-binding protein gene.

The role of retinoic acids (RA) on liver fatty acid-binding protein (L-FABP) expression was investigated in the well differentiated FAO rat hepatoma cell line. 9-cis-Retinoic acid (9-cis-RA) specifically enhanced L-FABP mRNA levels in a time- and dose-dependent manner. The higher induction was found 6 h after addition of 10(-6) M 9-cis-RA in the medium. RA also enhanced further both L-FABP mRNA levels and cytosolic L-FABP protein content induced by oleic acid. The retinoid X receptor (RXR) and the peroxisome proliferator-activated receptor (PPAR), which are known to be activated, respectively, by 9-cis-RA and long chain fatty acid (LCFA), co-operated to bind specifically the peroxisome proliferator-responsive element (PPRE) found upstream of the L-FABP gene. Our result suggest that the PPAR-RXR complex is the molecular target by which 9-cis-RA and LCFA regulate the L-FABP gene.

Alitretinoin↗

PubMed1996

Stimulation of proliferation of an essential fatty acid-deficient fish cell line by C20 and C22 polyunsaturated fatty acids and effects on fatty acid composition.

Recently we reported the development of a fish cell line, EPC-EFAD, derived from the carp (Cyprinus carpio) epithelial papilloma line, EPC, that could survive and proliferate in essential fatty acid-deficient (EFAD) medium. The EPC-EFAD cell line may be a useful model system in which to study the cellular biochemical effects of EFA deficiency and has advantages in studies of polyunsaturated fatty acid (PUFA) and eicosanoid metabolism in fish in that the complications introduced by culture in relatively n-6 PUFA-rich mammalian sera are removed. In the present study, the effects on cell proliferation rate of supplementing EPC-EFAD cells with various n-3 and n-6 PUFA were investigated to determine the possible role(s) of PUFA in cell growth and division. The selectivity of incorporation of specific PUFA into individual glycerophospholipid classes and the feasibility of reproducing in vivo fatty acid compositions in vitro were also investigated. Proliferation of the EPC-EFAD cell line was stimulated by arachidonic (20:4 n-6), eicosapentaenoic (20:5 n-3) and docosahexaenoic (22:6 n-3) fatty acids but not by 18:2 n-6 or 18:3 n-3. The differential effects of PUFA on cellular proliferation may be related to the lack of significant delta 5 desaturase activity in the cells at 22 degrees C and may implicate a role for eicosanoids in the mechanism of stimulation of proliferation. PUFA supplementation increased the cytotoxic effects of longer term culture, an effect that was partly alleviated by inclusion of vitamin E in the culture medium. The cells could generally be supplemented with PUFA to produce cellular fatty acid compositions in vitro that were similar to in vivo compositions.

Animals↗

PubMed2000

Effect of supplementation of arachidonic acid (AA) or a combination of AA plus docosahexaenoic acid on breastmilk fatty acid composition.

We investigated whether supplementation with arachidonic acid (20:4 omega 6; AA), or a combination of AA and docosahexaenoic acid (22:6 omega 3; DHA) would affect human milk polyunsaturated fatty acid (PUFA) composition. Ten women were daily supplemented with 300 mg AA, eight with 300 mg AA, 110 mg eicosapentaenoic acid (20:5 omega 3; EPA) and 400 mg DHA, for one week and eight women served as unsupplemented controls. Milk samples were collected on days 0, 1 and 7. The fatty acid composition of the milk was analyzed by capillary gas chromatography with flame ionisation detection. Supplementation with AA alone had no effect on breastmilk AA, but tended to reduce EPA and DHA levels. Administration of a combination of AA, EPA and DHA tended to increase both milk AA and long chain PUFA (LCPUFA)omega 3 content. A larger simultaneous increase of milk AA, DHA and EPA than observed in the present study can probably be accomplished by the use of a combination of a lower LCPUFA omega 6/LCPUFA omega 3 ratio and higher AA, EPA and DHA dosages.

Adult↗

PubMed2002

Functional role of fatty acyl-coenzyme A synthetase in the transmembrane movement and activation of exogenous long-chain fatty acids. Amino acid residues within the ATP/AMP signature motif of Escherichia coli FadD are required for enzyme activity and fatty acid transport.

Fatty acyl-CoA synthetase (FACS, fatty acid:CoA ligase, AMP forming; EC ) plays a central role in intermediary metabolism by catalyzing the formation of fatty acyl-CoA. In Escherichia coli this enzyme, encoded by the fadD gene, is required for the coupled import and activation of exogenous long-chain fatty acids. The E. coli FACS (FadD) contains two sequence elements, which comprise the ATP/AMP signature motif ((213)YTGGTTGVAKGA(224) and (356)GYGLTE(361)) placing it in the superfamily of adenylate-forming enzymes. A series of site-directed mutations were generated in the fadD gene within the ATP/AMP signature motif site to evaluate the role of this conserved region to enzyme function and to fatty acid transport. This approach revealed two major classes of fadD mutants with depressed enzyme activity: 1) those with 25-45% wild type activity (fadD(G216A), fadD(T217A), fadD(G219A), and fadD(K222A)) and 2) those with 10% or less wild-type activity (fadD(Y213A), fadD(T214A), and fadD(E361A)). Using anti-FadD sera, Western blots demonstrated the different mutant forms of FadD that were present and had localization patterns equivalent to the wild type. The defect in the first class was attributed to a reduced catalytic efficiency although several mutant forms also had a reduced affinity for ATP. The mutations resulting in these biochemical phenotypes reduced or essentially eliminated the transport of exogenous long-chain fatty acids. These data support the hypothesis that the FACS FadD functions in the vectorial movement of exogenous fatty acids across the plasma membrane by acting as a metabolic trap, which results in the formation of acyl-CoA esters.

Adenosine Monophosphate↗

PubMed2004

Mutation-induced quisqualic acid and ibotenic acid affinity at the metabotropic glutamate receptor subtype 4: ligand selectivity results from a synergy of several amino acid residues.

The metabotropic glutamate receptors (mGluRs) are key modulators of excitatory neurotransmission in the central nervous system. The eight mGluR subtypes are seven trans-membrane-spanning proteins that possess a large extracellular amino-terminal domain in which the endogenous ligand binding pocket resides. In this study, we have identified four non-conserved amino acid residues that are essential for differentiating mGluR1 from mGluR4. Our approach has been to increase the affinity of the classic mGluR1 agonists, quisqualic acid and ibotenic acid, at mGluR4 by making various point mutations that mimicked mGluR1 residues. Based on ligand docking to homology models, the non-conserved residues, Lys-74, Glu-287, Ser-313, and Lys-317, were chosen for the mutational studies and all of the mutations proved capable of partially or completely restoring the affinities of the ligands. In particular, the mutations K74Y and K317R induced dramatic triple-order-of-magnitude increases in the affinity of ibotenic acid at mGluR4, making the affinity equivalent to that of mGluR1. Furthermore, the affinity of quisqualic acid at mGluR4 was increased to the same level as mGluR1 by the two double mutations, K74Y/K317R and K74Y/E287G. Advanced analysis of ligand conformation and docking procedures were used for the interpretation of these results. The study shows that mGluR subtype selectivity results from a complex interplay of residues shaping the binding pocket, rather than being attributable to a single specific ligand-receptor interaction.

Cell Differentiation↗

PubMed1998

Addition of triglycerides with arachidonic acid or docosahexaenoic acid to infant formula has tissue- and lipid class-specific effects on fatty acids and hepatic desaturase activities in formula-fed piglets.

The effects of including triglycerides with arachidonic [20:4(n-6)] or docosahexaenoic acid [22:6(n-3)] in formula on plasma chylomicron, LDL and HDL, liver, heart, kidney and brain (n-6) and (n-3) fatty acids were investigated in formula-fed piglets. Piglets were fed formula with (in % total fatty acids) 20% 18:2(n-6) and 2% 18:3(n-3) without or with 0.8% 20:4(n-6) or 0.3% 22:6(n-3) from birth to 18 d. The effects of adding 20:4(n-6) or 22:6(n-3) to the formula differed among different tissues and lipids, with the brain showing resistance to change. Piglets fed formula with 20:4(n-6) had significantly higher plasma, heart and kidney phospholipid and triglyceride, and liver triglyceride 20:4(n-6), but lower plasma and tissue phospholipid 18:2(n-6) than piglets fed formula without 20:4(n-6). Supplementation with 22:6(n-3), in contrast, had no effect on plasma or tissue 18:2(n-6). Higher 22:6(n-3) in liver phospholipid (30-92% greater) and triglyceride (200% greater) in piglets fed formula with 22:6(n-3) rather than without 22:6(n-3) was accompanied by lower 20:4(n-6) in liver phosphatidylethanolamine (mean +/- SEM, 8.6 +/- 0.4 and 10.5 +/- 0.4% fatty acids, respectively), but higher 20:4(n-6) in triglyceride (5.2 +/- 0.4 and 11.5 +/- 0.5%, respectively), and higher liver, heart and kidney phospholipid 20:5(n-3). These results indicate competitive interaction between dietary 20:4(n-6) and tissue 18:2(n-6), and between dietary 20:4(n-6) and tissue 20:5(n-3), rather than 22:6(n-3). The results also show that even at low intakes, dietary 22:6(n-3) or 20:4(n-6) supplementation alters the tissue phospholipid 20:4(n-6) to 20:5(n-3) balance. Studies on the physiologic effects of dietary 20:4(n-6) and 22:6(n-3) supplementation should consider the different sensitivity among tissues to dietary fatty acids.

Animals↗

PubMed1988

4-Aminosalicylic acid, in contrast to 5-aminosalicylic acid, has no effect on arachidonic acid metabolism in human neutrophils, or on the free radical 1,1-diphenyl-2-picrylhydrazyl.

5-Aminosalicylic acid seems to be the active moiety of sulfasalazine in the treatment of chronic inflammatory bowel disease. Even if the precise mode of action is obscure, it is assumed that two of the main mechanisms are inhibitory effects on the lipoxygenation of arachidonic acid and interaction with free radicals. As 4-aminosalicylic acid has been claimed to be beneficial in the topical treatment of ulcerative colitis, it was tested whether this drug possesses any influence on the 5-lipoxygenase activity in human neutrophils in vitro or whether it acts as a radical scavenger. The change of the amino residue from carbon-5 to carbon-4 abolished the effect in the two systems tested. The reported clinical observations on 4-aminosalicylic acid in the treatment of chronic inflammatory bowel disease remain to be confirmed and cannot be explained by interference with arachidonic acid metabolism or free oxygen radicals.

Aminosalicylic Acid↗

PubMed1976

[Investigations on the utilization of parenterally administered amino acids in premature and small-for-dates neonates. IV. Control of the amino acid blood level during infusion of a pharmacokinetically balanced amino acid solution (author's transl)].

An amino acid solution composed according to pharmacokinetic criteria was infused in 12 premature and 4 full-term infants. Imbalances of amino acids were not observed when the upper limit of the fasting level was accepted as a measure for balance or imbalance. The net transfer of total amino acids increased by about 40% over that in former experiments (second communication (4)). A decrease of cystine, a semiessential amino acid, could be avoided. The results were compared with the literature. During infusion, the urinary excretion of amino acids was not increased showing nearly complete utilization of the infused amin acids.

Amino Acids↗

PubMed1996

Identification of the acidic degradation products of hexenuronic acid and characterisation of hexenuronic acid-substituted xylooligosaccharides by NMR spectroscopy.

A 4-O-methylglucuronoxylan was converted into a hexenuronoxylan at high temperature and alkalinity similar to the conditions used during kraft pulping. The hexenuronoxylan was hydrolysed with enzymes, and acidic xylooligosaccharides were separated from the hydrolysate by anion-exchange and size-exclusion chromatography. The primary structure of the two main hexenuronic acid-substituted xylooligosaccharides (a tetramer and a pentamer) was determined by two-dimensional 1H and 13C NMR spectroscopy. The 4-deoxy-hexenuronic acid is not stable under the acid hydrolysis step of conventional carbohydrate analysis. Here, we have identified the acidic degradation products of 4-deoxy-hexenuronic acid by NMR spectroscopy. Two degradation pathways were observed, both resulting in a furan derivative.

Carbohydrate Sequence↗

PubMed1988

Fine distribution of gamma-aminobutyric acid, glutamic acid decarboxylase, and glutamic acid in the rabbit cerebellum.

The fine distribution of GABA, glutamic acid decarboxylase, and glutamic acid within each layer of the rabbit cerebellar cortex was determined with microanalytical methods. The greatest glutamic acid decarboxylase activity and the highest GABA concentration were found in the Purkinje cell layer. In the distribution of GABA and glutamic acid decarboxylase the peak of glutamic acid decarboxylase activity was more pronounced than that of GABA; the concentration of glutamic acid did not show much variation between each layer.

Animals↗

PubMed2003

The first total synthesis of the marine fatty acid (+/-)-9-methoxypentadecanoic acid: a synthetic route towards mid-chain methoxylated fatty acids.

The marine fatty acid (+/-)-9-methoxypentadecanoic acid was synthesized for the first time in seven steps (7.8% overall yield) starting from commercially available 9-decen-1-ol. The key step in the synthesis was the coupling of pentylmagnesium bromide with 1-benzyloxy-9,10-epoxydecane under 1,5-cyclooctadiene copper (I) chloride catalysis. Nuclear magnetic resonance data are provided for the first time for this type of methoxylated fatty acids and the synthetic approach utilized is of general applicability since it can be used in the synthesis of other mid-chain methoxylated fatty acids. This synthetic methodology should afford sufficient quantities of these fatty acids for biological evaluation. The spectral data obtained for the title compound will also be helpful in subsequent characterizations of other mid-chain methoxylated fatty acids using nuclear magnetic resonance spectroscopy.

Fatty Acids↗

PubMedDate not supplied

Phenylboronic acid-salicylhydroxamic acid bioconjugates. 1. A novel boronic acid complex for protein immobilization.

A chemical affinity system exhibiting antibody-like properties is described. The system exploits bioconjugates with appended phenylboronic acid (PBA) moieties and a support-bound phenylboronic acid complexing reagent derived from salicylhydroxamic acid (SHA) for protein immobilization on a chromatographic support. The structure of the PBA.SHA complex was characterized by 11B NMR and mass spectrometry and compared with complexes derived from model compounds. Protein modification reagents were synthesized from 3-aminophenylboronic acid and utilized to prepare bioconjugates from alkaline phosphatase (AP) and horseradish peroxidase (HRP). AP obtained from one source afforded PBA bioconjugates exhibiting significant loss of enzymatic activity, whereas AP obtained from a second source afforded PBA bioconjugates exhibiting only a modest loss of enzymatic activity. Conversely, HRP afforded PBA bioconjugates exhibiting no loss of enzymatic activity. SHA-modified Sepharose was prepared by reaction of methyl 4-[(6-aminohexanoylamino)methyl]salicylate with CNBr-activated Sepharose 4B, followed by treatment with aqueous alkaline hydroxylamine. PBA-AP and PBA-HRP conjugates were efficiently immobilized on SHA-Sepharose at pH 8.3. PBA-AP conjugates were retained after washing with acidic buffers at pH 6.7, 4.2, and 2.5, whereas PBA-HRP conjugates were retained after washing with buffer at pH 6.7, but were eluted to some extent at and below pH 4.2. The results are interpreted in terms of multivalent interactions involving boronic acid complex formation between the enzyme bioconjugates and immobilized complexing reagent.

Alkaline Phosphatase↗

PubMed2001

Dinuclear chromium(V) amino acid complexes from the reduction of chromium(VI) in the presence of amino acid ligands: XAFS characterization of a chromium(V) amino acid complex.

The first synthesis and characterization of Cr(V) complexes of non-sulfur-containing amino acids are reported. The reduction of Cr(VI) in methanol in the presence of amino acids glycine, alanine, and 2-amino-2-methylpropanoic acid (alpha-aminoisobutyric acid, Aib) yielded several Cr(V) EPR signals. For the reaction involving glycine, the only Cr(V) EPR signals detected were those of the Cr(V)-intermediate methanol complexes, which were also observed in the absence of amino acids. The reaction involving alanine yielded one Cr(V) signal with a g(iso) value of 1.9754 (a(iso) = 4.88 x 10(-4) cm(-1) and A(iso)(53Cr) = 17.89 x 10(-4) cm(-1)). However, a solid product isolated from the reaction solution was EPR silent and was characterized as a dioxo-bridged dimeric species, [Cr(V)2(mu-O)2(O)2(Ala)2(OCH3)2](2-), by multiple-scattering XAFS analysis and electrospray mass spectrometry. The EPR spectrum of the reduction reaction of Cr(VI) in the presence of Aib showed several different Cr(V) signals. Those observed at lower g(iso) values (1.9765, 1.9806) were assigned to Cr(V)-methanol intermediates, while the relatively broad six-line signal at g(iso) = 2.0058 was assigned as being due to a Cr(V) complex with coupling to a single deprotonated amine group of the amino acid. This was confirmed by simplification of the superhyperfine coupling lines from six to three when the deuterated ligand was substituted in the reaction. The reduction of Cr(VI) with excess alanine or Aib ligands resulted in the formation of tris-chelate Cr(III) complexes, which were analytically identical to complexes formed via Cr(III) synthesis methods. The fac-[Cr(Aib)3] complex was characterized by single-crystal X-ray diffraction.

Amino Acids↗

PubMed2001

Bioactivation of chemopreventive selenocysteine Se-conjugates and related amino acids by amino acid oxidases novel route of metabolism of selenoamino acids.

Several selenocysteine Se-conjugates have been shown to possess potent chemopreventive activity in animal models for chemical carcinogenesis. As a mechanism of action, beta-elimination reactions to form chemopreventive selenols, ammonia, and pyruvate has been proposed. The enzymes involved in these beta-elimination reactions, however, have been partially elucidated. Next to cysteine conjugate beta-lyases, as yet unidentified non-pyridoxal-5'-phosphate-dependent enzymes also appear to be involved in cytosolic beta-elimination reactions. In the present study, it was investigated whether amino acid oxidases contribute to the bioactivation of selenocysteine Se-conjugates. Using purified L-amino acid oxidase from Crotalus adamanteus as a model enzyme, significant beta-elimination activities were indeed observed upon incubation with Se-methylselenocysteine (K(m), 195 microM; k(cat), 48 min(-1)), Se-allylselenocysteine (K(m), 608 microM; k(cat), 34 min(-1)), Se-phenylselenocysteine (K(m), 107 microM; k(cat), 57 min(-1)) and Se-benzylselenocysteine (K(m), 59 microM; k(cat), 13 min(-1)). For all selenocysteine Se-conjugates tested, the rate of pyruvate formation was comparable to that of hydrogen peroxide, one of the products of oxidative deamination. The fact that addition of catalase did not alter pyruvate formation indicated that the beta-elimination reaction observed was not mediated by selenoxidation/syn-elimination due to the hydrogen peroxide formed via the oxidative deamination pathway. Using D-amino acid oxidase from porcine kidney and D-SeCys conjugates similar results were obtained. To delineate whether mammalian L-amino acid oxidases are also able to catalyze beta-elimination of selenocysteine Se-conjugates, rat renal cytosol was fractionated and screened for beta-elimination and oxidative deamination activities. One of the fractions isolated displayed oxidative deamination activity with several amino acids and cysteine S-conjugates. With selenocysteine Se-conjugates as substrates, however, this fraction displayed both oxidative deamination and beta-elimination activities, when incubated in the presence of aminoxyacetic acid to block contribution of pyridoxal-5'-phosphate-dependent enzymes. The potential significance of this novel bioactivation route for the chemopreventive activity of selenocysteine Se-conjugates is discussed.

Amino Acid Oxidoreductases↗