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PubMed1977

Origin of hydrogen atoms in the fatty acids synthesized with yeast fatty acid synthetase.

The mechanism of hydrogen incorporation into fatty acids was investigated with an enzyme preparation from baker's yeast. Fatty acids synthesized from malonyl-CoA and acetyl-CoA in the presence of D2O or stereospecifically deuterium-labeled NADPH were isolated and analyzed by mass chromatography to examine the localization of deuterium atoms in the molecule. The following results were obtained: 1. Hydrogen atoms from water were found on the even-numbered methylene carbon atoms (2-hydrogen atoms per carbon atom). The second hydrogen atom was incorporated as the result of hydrogen exchange phenomenon between the methylene group of malonyl CoA and water. 2. HB hydrogen of NADPH was used for beta-ketoacyl reductase. 3. HB hydrogen of NADPH was also used for enoyl reductase. 4. Hydrogen atoms from HB position of NADPH were found on the odd-numbered methylene carbon atoms (2-hydrogen atoms per carbon atom).

Deuterium↗
PubMed1989

Deficiencies of polyunsaturated fatty acids and replacement by nonessential fatty acids in plasma lipids in multiple sclerosis.

Fatty acid compositions of plasma phospholipids, cholesteryl esters, triacylglycerols, and nonesterified fatty acids of 14 clinically proven and graded cases of multiple sclerosis were determined by capillary gas chromatography and compared with the values obtained for 100 normal, healthy subjects. In phospholipids, linoleic acid (18:2 omega 6; 18 carbon atoms, 2 double bonds, 6 carbon atoms beyond last double bond) was normal and 18:3 omega 6 was increased, but all subsequent omega 6 acids were subnormal (P less than 0.001), indicating impairment of chain elongation. All omega 3 acids were subnormal. The paucity of polyunsaturated fatty acids was compensated mass-wise by an increase in saturated acids. Disproportionate increases in short-chain, saturated, and monounsaturated acids, decreases in long-chain homologs, and increases of branched and odd-chain acids were observed. Loss of polyunsaturated fatty acids and replacement by nonessential acids lowered mean chain length and raised mean melting point significantly, suggesting that lowered membrane fluidity was only partially compensated by endogenous synthesis of lower-melting, nonessential acids. This phenomenon was not observed in cholesteryl esters or triacylglycerols. Nonesterified fatty acids showed significant changes in pattern of possible autacoid precursors. The abnormal profile of fatty acids in multiple sclerosis has features in common with profiles of other syndromes involving viral infections.

Adult↗
PubMed2000

Dietary trans fatty acids affect the essential fatty-acid concentration of rat milk.

Increasing efforts have been made to determine the distribution and concentration of trans fatty acids in milk, due to the importance of lipids in infant growth and development. In general, trans fatty acid concentration of milk reflects trans fatty acid intake, but insufficient data are available to assess the effects of dietary trans fatty acids on maternal milk. Thus, controlled studies are needed to establish whether there is a dose-response relationship and whether trans fatty acids could affect the concentration of essential fatty acids (EFA), long-chain polyunsaturated fatty acids (PUFA) and the (n-6)/(n-3) ratio in milk. Three groups of six rats each were fed for 10 wk one of three diets differing in trans fatty acid concentration (Control, 0 mol/100 mol; high trans concentration (H), 14.5 mol/100 mol; very high trans concentration (VH), 30 mol/100 mol), but containing the same proportions of linoleic and alpha-linolenic acids and a ratio of 18:2(n-6)/18:3(n-3) of about 7:1. Trans fatty acids were incorporated into maternal milk in a dose-dependent manner. In addition, rats fed trans isomers had greater linoleic acid levels than controls. The proportion of alpha-linolenic acid in milk was lower in the VH group, and the (n-6)/(n-3) cis PUFA ratio in milk of the VH group was greater than that in controls. Total long-chain PUFA levels did not differ among groups. These results suggest that high intakes of trans fatty acids affect the EFA concentration but not that of long-chain PUFA of rat milk, provided that EFA are supplied in sufficient amounts.

Animals↗
PubMed1997

Cytoplasmic codiffusion of fatty acids is not specific for fatty acid binding protein.

The intracellular movement of fatty acids is thought to be facilitated through codiffusion with fatty acid binding protein (FABP). Previous work suggested that FABP decreases fatty acid binding to immobile membranes, causing faster cytoplasmic diffusion. However, the specificity for binding to FABP has not been addressed. The aim of the current study was to determine whether specific FABP binding is required or whether binding to other proteins will produce the same effect. A model cytoplasm consisted of a fatty acid, proteins, and liposomes to simulate intracellular membranes. Laser photobleaching (fluorescence recovery after photobleaching) was used to measure the movement of the fluorescent fatty acid 12-N-methyl-7-nitrobenzo-2-oxa-1,3-diazoaminostearate (NBD-stearate) in model cytoplasm, in normal and permeabilized Hep G2 cells, and after incubation of permeabilized cells with bovine serum albumin (BSA) or FABP. Increasing protein in the model cytoplasm increased the diffusion rate in proportion to the extent of protein binding. Cell permeabilization reduced diffusion of NBD-stearate to < 5% of controls. Incubation of permeabilized cells with FABP or BSA resulted in a concentration-dependent increase in the NBD-stearate diffusion rate. BSA was more effective than FABP in binding NBD-stearate and increasing its diffusion rate after permeabilization. Proteins like FABP promote the diffusion of fatty acids. Removal of these proteins drastically reduces cytoplasmic diffusion. Substitution with BSA reestablishes the diffusive flux, suggesting that specific binding to FABP is not required. These data support a role for intracellular binding proteins in facilitating the cytoplasmic movement of fatty acids.

4-Chloro-7-nitrobenzofurazan↗
PubMed1997

Regulation of Triacylglucose Fatty Acid Composition (Uridine Diphosphate Glucose:Fatty Acid Glucosyltransferases with Overlapping Chain-Length Specificity).

UDP-glucose (UDP-Glc):fatty acid glucosyltransferases catalyze the UDP-Glc-dependent activation of fatty acids as 1-O-acyl-[beta]-glucoses. 1-O-Acyl-[beta]-glucoses act as acyl donors in the biosynthesis of 2,3,4-tri-O-acylglucoses secreted by wild tomato (Lycopersicon pennellii) glandular trichomes. The acyl composition of L. pennellii 2,3,4-tri-O-acylglucoses is dominated by branched short-chain acids (4:0 and 5:0; approximately 65%) and straight and branched medium-chain-length fatty acids (10:0 and 12:0; approximately 35%). Two operationally soluble UDP-Glc:fatty acid glucosyltransferases (I and II) were separated and partially purified from L. pennellii (LA1376) leaves by polyethylene glycol precipitation followed by DEAE-Sepharose and Cibacron Blue 3GA-agarose chromatography. Whereas both transferases possessed similar affinity for UDP-Glc, glucosyltransferase I showed higher specificity toward short-chain fatty acids (4:0) and glucosyltransferase II showed higher specificity toward medium-chain fatty acids (8:0 and 12:0). The overlapping specificity of UDP-Glc:fatty acid glucosyltransferases for 4:0 to 12:0 fatty acid chain lengths suggests that the mechanism of 6:0 to 9:0 exclusion from acyl substituents of 2,3,4-tri-O-acylglucoses is unlikely to be controlled at the level of fatty acid activation. UDP-Glc:fatty acid glucosyltransferases are also present in cultivated tomato (Lycopersicon esculentum), and activities toward 4:0, 8:0, and 12:0 fatty acids do not appear to be primarily epidermal when assayed in interspecific periclinal chimeras.

Journal Article↗
PubMed1992

Relationship between the degree of unsaturation of dietary fatty acids and adipose tissue fatty acids assessed by natural-abundance 13C magnetic resonance spectroscopy in man.

Natural-abundance 13C magnetic resonance spectroscopy was used for determining noninvasively the relative concentration of mono- and polyunsaturated fatty acids of adipose tissue in two groups of volunteers. The first consisted of subjects who had followed a fat-reduced diet for at least half a year before the 13C measurements. The second were control subjects who were on a usual high-fat diet. The ratio of unsaturated to total fatty acids in adipose tissue determined by 13C MRS correlated significantly with the same ratio in fat of the diet composition estimated by a dietician according to food records. The results indicate that 13C MRS is capable of assessing the degree of unsaturation of dietary fatty acids consumed during the preceding months.

Adipose Tissue↗
PubMed1980

Relationship of primer specificity of fatty acid de novo synthetase to fatty acid composition in 10 species of bacteria and yeasts.

Fatty acid compositions of lipids from six bacteria and four yeasts were determined. Fatty acid de novo synthetases were investigated with respect to chain length specificity towards acyl-CoA primers of various chain lengths. Four species of bacteria (Bacillus subtilis, Corynebacterium cyclohexanicum, Micrococcus luteus, and Pseudomonas maltophilia) possess branched-chain fatty acids of the iso and anteiso series as the major acids. De novo synthetases from these organisms exhibited specificity towards the chain length of the primer in the order butyl-CoA > priopionyl-CoA > acetyl-CoA. The remainder, two bacteria and all four yeasts, have the straight-chain type of fatty acids only and fall into two groups: (1) Eschericia coli B, Pseudomonas fluorescens, and Saccharomyces cerevisiae, which utilize the primers in the order acetyl-CoA > priopionyl-CoA > butyryl-CoA; and (2) Candida sake, Candida tropicalis, and Rhodotorula glutinis, which show the order propionyl-CoA > acetyl-CoA > butyryl-CoA. L-alpha-Keto-beta-methylvalerate, a precursor of the branched-chain primers, can be used as a source of primer for fatty acid synthesis by the organisms with branched-chain acids but not by those with the straight-chain type. The results indicate that organisms having straight-chain fatty acids lack the branched-chain equivalents for two reasons: first, their enzymes are not active toward primers with more than three carbons, and second, they lack a system of supply suitable branched-chain primers. It appears that activities of de novo synthetases from the organisms having straight-chain fatty acids generally have much higher activities than those from the organisms possessing branched-chain fatty acids

Acyl Coenzyme A↗
PubMed1997

Isoforms of rat liver fatty acid binding protein differ in structure and affinity for fatty acids and fatty acyl CoAs.

Although native rat liver fatty acid binding protein (L-FABP) is composed of isoforms differing in isoelectric point, their comparative structure and function are unknown. These properties of apo- and holo-L-FABP isoforms were resolved by circular dichroism, time-resolved fluorescence spectroscopy, and binding/displacement of fluorescent ligands. Both apo-isoforms had similar hydrodynamic radii of 18.5 A, but apo-isoform I had a greater alpha-helical content and exhibited a longer Tyr lifetime, indicative of secondary and tertiary structural differences from isoform II. Isoforms I and II both had two fatty acid or fatty acyl CoA binding sites. Ligand binding decreased the isoform hydrodynamic radii by 3-4 A and increased Tyr rotational motions in a more restricted range. Fatty acyl CoAs were more effective than fatty acids in altering the isoform structures. Scatchard analysis showed that both isoforms bound cis- parinaric acid with high affinity (Kd values 41 and 60 nM, respectively) and bound trans-parinaric acid with 2- and 7-fold, respectively, higher affinity than for cis-parinaric acid. In contrast, isoform I had higher affinity for cis- and trans-parinaroyl CoAs (Kd values of 33 and 14 nM) than did isoform II (Kd values of 110 and 97 nM), thereby resulting in biphasic plots of parinaroyl-CoA binding to native L-FABP. Finally, displacement studies indicated that each isoform displayed distinct specificities for fatty acid/fatty acyl CoA chain length and unsaturation. Thus, rat L-FABP isoforms differ markedly in both structure and ligand binding function.

Acyl Coenzyme A↗
PubMed1996

Effect of dietary n-9 eicosatrienoic acid on the fatty acid composition of plasma lipid fractions and tissue phospholipids.

n-9 Eicosatrienoic acid (ETrA), also known as Mead acid, is a minor fatty acid in essential fatty acid (EFA)-sufficient healthy subjects but is found at increased levels in EFA deficiency. This study examined the influence of dietary ETrA from a biological source on plasma and tissue ETrA. A synthetic fat-free diet was prepared to which was added Mut 48 oil which contains 19% ETrA (wt%) as well as other n-9 fatty acids. Blends of vegetable oils were used to achieve overall diets with 5% fat (wt%) and varying amounts of ETrA at two different dietary levels of linoleic acid (LA), approximately 4.4 and 19% of total fatty acids. These diets were fed to 5-week-old Dark Agouti rats for four weeks. Plasma lipid fractions and liver, spleen, and peritoneal exudate (PE) cells were analyzed for fatty acid composition. ETrA was present at up to 20% total fatty acids in plasma triglyceride, cholesterol ester, and phospholipid fractions. ETrA also accumulated to substantial levels in phospholipids of liver and spleen (up to 15% of total fatty acids) and PE cells (up to 11%). ETrA was found in plasma and tissue phospholipids in proportion to the amount of ETrA present in the diet. The incorporation was reduced in diets with higher LA content compared to diets containing similar amounts of ETrA but lower LA. All rats remained apparently healthy, and histological survey of major organs revealed no abnormality. While the long-term implications for health of ingestion of diets rich in ETrA remain to be established, rats appear to tolerate high levels of dietary ETrA without adverse effects. Dietary enrichment with ETrA warrants further investigation for possible beneficial effects in models of inflammation and autoimmunity, as well as in other conditions in which mediators derived from n-6 fatty acids can affect homeostasis adversely.

8,11,14-Eicosatrienoic Acid↗
PubMed1989

Regulation of transmembrane ion transport by reaction products of phospholipase A2. II. Effects of arachidonic acid and other fatty acids on mitochondrial Ca2+ transport.

The effects of arachidonic acid and other fatty acids on mitochondrial Ca2+ transport were studied. Cis-unsaturated fatty acids generally strongly inhibited mitochondrial Ca2+ uptake, induced a net Ca2+ efflux, and thereby increased the extramitochondrial Ca2+ concentration, whereas trans-unsaturated fatty acids were ineffective. Saturated fatty acids exhibited slight activity at chain lengths from C(10) to C(14) only. The structure-activity relationship and the inability of some of the effective fatty acids such as palmitoleic and myristoleic acid to be metabolized to eicosanoids suggest that Ca2+ release was induced by the fatty acids themselves and resulted from changes in the mitochondrial membrane bilayer structure. There was a correlation between Ca2+-releasing potency and reduction of mitochondrial membrane potential, which is the main driving force for mitochondrial Ca2+ uptake. There were, however, considerable differences compared with the effects of lysophospholipids on the membrane potential. The mechanism of action of fatty acids may be that of a fluidizing effect on the hydrophobic core of the membrane, thereby modulating the activity of integral membrane proteins of the respiratory chain.

Animals↗
PubMed1984

Thermodynamic bases for fatty acid ethyl ester synthase catalyzed esterification of free fatty acid with ethanol and accumulation of fatty acid ethyl esters.

Myocardial homogenates rapidly synthesize fatty acyl ethyl esters from nonesterified fatty acid and ethanol in the absence of coenzyme A or ATP, and the enzyme catalyzing this reaction, fatty acid ethyl ester synthase, has been purified 5400-fold to homogeneity [Mogelson, S., & Lange, L. G. (1984) Biochemistry (preceding paper in this issue)]. To define the factors permitting this de novo synthesis of ester bonds and the consequent accumulation of fatty acyl ethyl esters in myocardium, we determined thermodynamic parameters relevant to the kinetics and equilibria of this reaction and specifically characterized (1) the rates of synthesis of ethyl oleate, in both the presence and absence of purified enzyme catalyst, and (2) the physical properties of the product, ethyl oleate, in an aqueous milieu. Compared to the reaction of ethanol and oleate in the absence of catalyst, fatty acid ethyl ester synthase enhanced the rate of ethyl oleate synthesis by reducing the free energy of activation (delta G) from 32.5 to 19.9 kcal/mol, effected in large part by a positive entropy shift, delta Senz - delta S uncat = 23.9 cal/(mol.deg). Rate constants in the presence and absence of enzyme at 37 degrees C were 6 X 10(-2) s-1 and 7.8 X 10(-11) M-1 s-1, respectively, indicating a catalytic power of at least 10(8)M for this enzyme. Kinetic data indicated an enzymatic Vmax of 1.25 nmol/(mg.s) (37 degrees C). The equilibrium constant was calculated for the reaction oleate + ethanol in equilibrium ethyl oleate and was 0.095 M-1 at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Acyltransferases↗
PubMed2001

Hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition of liver in salmonids: effects of dietary vegetable oil.

The desaturation and elongation of [1-(14)C]18:3n-3 was investigated in hepatocytes from different populations and three different species of salmonids indigenous to Scotland, brown trout, Atlantic salmon and Arctic charr. Two groups of fish were sampled, before and after they were fed two experimental diets, a control diet containing fish oil and a diet containing vegetable oil (a 1:1 blend of linseed and rapeseed oils) for 12 weeks. At each sampling time, fatty acyl desaturation and elongation activity was determined in isolated hepatocytes, and samples of liver were also collected for lipid compositional analysis. At the initiation of the dietary trial, the liver polar-lipid fatty acid compositions of salmon and brown trout were very similar to each other, and the two charr populations were similar to each other, having lower total n-3 polyunsaturated fatty acids (PUFA) and 22:6n-3, but higher 20:5n-3 than the other salmonids. Initially, hepatocyte desaturation activity varied, with the highest activity in brown trout, followed by salmon and then charr. Production of 20:5n-3 was particularly high in brown trout. Desaturation of [1-(14)C]18:3n-3 was significantly greater in all fish fed the diet containing vegetable oil compared to fish fed the diet containing fish oil. The increase in activity was less in brown trout compared to the other groups of fish. Feeding the vegetable oil diet increased the levels of 18:2n-6, 20:3n-6, total n-6 PUFA, 18:3n-3, 18:4n-3, 20:3n-3 and 20:4n-3, and decreased 22:6n-3 and the n-3/n-6 ratio in salmon and brown trout. By contrast, in charr fed the vegetable oil diet, there was no increase in 18:3n-3, 18:4n-3, 20:3n-3 or 20:4n-3 in liver polar lipids and the level of 22:6n-3 was not decreased. In addition, there was only a modest increase in the levels of 18:2n-6 and total n-6 PUFA, and so the n-3/n-6 ratio was only slightly decreased. The percentage of 20:4n-6, which was not increased in salmon and brown trout fed vegetable oil, was increased in charr fed the vegetable oil diet. Overall, the results indicated that there were significant differences in liver PUFA metabolism between Arctic charr and the other salmonids, which could have important consequences, both physiologically and in their ability to be successfully cultured on diets containing vegetable oils.

Animal Feed↗
PubMed1977

Biosynthesis of cyclopentenyl fatty acids. Cyclopentenylglycine, a non-proteinogenic amino acid as precursor of cyclic fatty acids in Flacourtiaceae.

In seeds of Hydnocarpus anthelminthica of Flacourtiaceae, cyclopentenylglycine and cyclopentenyl fatty acids are found naturally. The non-proteinogenic amino acid may serve as precursor of cyclopentenyl fatty acids via aleprolic acid, the starter molecule for these long-chain compounds. After administration of cyclopentenyl[2-14C]glycine to maturing seeds of H. anthelminthica, labelled cyclopentenyl fatty acids were synthesized. Comparative activities were observed, when [1-14C]aleprolic acid was supplied to the seeds. Incorporation studies with [1-14C]acetate revealed that the chain-lengthening systems for straight-chain and cyclic fatty acids were still functioning in mature seeds. Endosperm and embryo of H. Anthelminthica seeds synthesized cyclopentenyl fatty acids from cyclopentenyl[2-14C]glycine, [1-14C]aleprolic acid and [1-14C]acetate. In embryonic tissue, a dilution experiment proved the following path for cyclopentenyl fatty acid biosynthesis: cyclopentenylglycine leads to aleprolic acid leads to cyclopentenyl fatty acids. The conversion of cyclopentenylglycine to aleprolic acid may occur via transamination and oxidative decarboxylation; activated aleprolic acid is then lengthened by C2-units to cyclopentenyl fatty acids.

Acetates↗
PubMed1981

Fatty acid synthetase from the Harderian gland of guinea pig: biosynthesis of methyl-branched fatty acids.

Fatty acid synthetase was isolated from guinea pig Harderian gland. This enzyme complex exhibited a unique character as compared with the fatty acid synthetase from the liver of the same animal. The former enzyme produced many odd-numbered and methyl-branched fatty acids in the presence of methylmalonyl-CoA. These fatty acids are characteristic components of the lipid secreted from this gland. The chemical structure of this lipid has been identified as 1-O-alkyl-2,3-diacylglycerol by previous work from this laboratory (Yamazaki, T., Seyama, Y., Otsuka, H., Ogawa, H., & Yamakawa, T. (1981) J. Biochem. 89, 683-691). Apparent Km values (5 X 10(-6) M) for acetyl-CoA and propionyl-CoA were the same, but the Vmax for propionyl-CoA was much higher than that for acetyl-CoA. The pI value of the fatty acid synthetase from Harderian gland was 5.3, and the molecular weight of the enzyme was 9 X 10(5) daltons. The beta-ketoacyl reductase had pro-S stereospecificity and the enoly reductase had pro-R stereospecificity for NADPH. The results presented in this paper indicate that the fatty acid synthetase from guinea pig Harderian gland can produce a set of fatty acids needed for the synthesis of the lipid secreted from this gland, and that the fatty acid synthetase has a characteristic organ specificity.

Acetyl Coenzyme A↗
PubMed2004

Improving the fatty acid profile of fairy shrimp, Streptocephalus dichotomus, using a lipid emulsion rich in highly unsaturated fatty acids.

Fatty acids are the largest component of lipids and have become a useful tool in the determination of live feeds to a variety of cultured species. Bioencapsulation is a technique which allows high-level incorporation of desired components (i.e., fatty acids, vitamins, antibiotics, etc.) in live feeds, which in turn can be supplemented to the consumer organisms. The procedure described in the present study serves as a platform of technology for enriching the Streptocephalus dichotomus. Uptake of two enrichment diets (ALGAMAC2000 and DHA-SELCO) by adult S. dichotomus was investigated. The fatty acid profile supports the hypothesis that the enrichment diet increases the level of essential fatty acids, such as linolic, linolenic, eicosapentenoic, and docosahexaenoic acids. The average content (percent of total fatty acids detected) of the enriched organism by different highly unsaturated fatty acid (HUFA) products were as follows: ALGAMAC2000 showed 14-22% saturated fatty acid (SFA), 17-18% monounsaturated fatty acid (MUFA), 28-41% polyunsaturated fatty acid (PUFA), 23-34% n-3, and 4.9-7.5% n-6, whereas DHA-SELCO showed about 20-23% SFA, 20-26% MUFA, 38% PUFA, 28-31% n-3, and 7.5-10% n-6. Our present investigation proves that both HUFA-rich diets appear to be an appropriate enrichment diet, and further provides an additional rationale for using fairy shrimp as a maturation diet for any cultivable freshwater organism.

Animals↗