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PubMed1992

Effects of saturated fatty acids on prostaglandin E 9-keto-reductase.

We examined the effects of three saturated fatty acids (myristic acid 14:0, palmitic acid 16:0, and stearic acid 18:0) on prostaglandin E 9-ketoreductase (PGE-9-KR, EC 1.1.1.189), which catalyzes the conversion of prostaglandin E2 (PGE2) into prostaglandin F2 alpha (PGF2 alpha). Palmitic acid inhibited PGE-9-KR activity dose-dependently, whereas the other two fatty acids had no effect. In spite of the structural similarity of these fatty acids, our findings suggest that, of the three, only palmitic acid has an inhibitory effect on PGE-9-KR.

Catalysis↗
PubMed1998

Fatty acylation of polypeptides in the nematode Caenorhabditis elegans.

Covalent modification of eucaryotic proteins, involving addition of fatty acyl groups, is a widespread phenomenon. Here we describe the occurrence of this form of covalent modification in the free-living nematode, Caenorhabditis elegans. Following incubation in the presence of either [3H]-myristic acid or [3H]-palmitic acid, specific C. elegans polypeptides became labelled. Chemical analysis revealed that following incubation of C. elegans with [3H]-myristic acid, polypeptides became labelled with myristoyl, palmitoyl or stearoyl moieties; after incubation with [3H]-palmitic acid, palmitoyl or stearoyl moieties were incorporated into polypeptides. Fatty acyl groups were linked to target polypeptides, predominantly through alkali-labile thioester or ester linkages and acid-labile amide linkages. Where myristoylation involved an amide linkage, the modified amino acid was usually glycine. Preliminary immunological evidence indicated that heterotrimeric GTP-binding protein alpha subunit(s) are possible target(s) for acylation in C. elegans.

Acylation↗
PubMed1999

Possible involvement of proteolytic degradation of tyrosinase in the regulatory effect of fatty acids on melanogenesis.

The purpose of this study was to investigate the mechanism of fatty acid-induced regulation of melanogenesis. An apparent regulatory effect on melanogenesis was observed when cultured B16F10 melanoma cells were incubated with fatty acids, i.e., linoleic acid (unsaturated, C18:2) decreased melanin synthesis while palmitic acid (saturated, C16:0) increased it. However, mRNA levels of the melanogenic enzymes, tyrosinase, tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2), were not altered. Regarding protein levels of these enzymes, the amount of tyrosinase was decreased by linoleic acid and increased by palmitic acid, whereas the amounts of TRP1 and TRP2 did not change after incubation with fatty acids. Pulse-chase assay by [35S]methionine metabolic labeling revealed that neither linoleic acid nor palmitic acid altered the synthesis of tyrosinase. Further, it was shown that linoleic acid accelerated, while palmitic acid decelerated, the proteolytic degradation of tyrosinase. These results suggest that modification of proteolytic degradation of tyrosinase is involved in regulatory effects of fatty acids on melanogenesis in cultured melanoma cells.

Animals↗
PubMed1999

Effect of fatty acid chain length and saturation on the gastrointestinal handling and metabolic disposal of dietary fatty acids in women.

The gastrointestinal handling and metabolic disposal of [1-13C]palmitic acid, [1-13C]stearic acid and [1-13C]oleic acid administered within a lipid-casein-glucose-sucrose emulsion were examined in normal healthy women by determining both the amount and nature of the 13C label in stool and label excreted on breath as 13CO2. The greatest excretion of 13C label in stool was in the stearic acid trial (9.2% of administered dose) whilst comparatively little label was observed in stool in either the palmitic acid (1.2% of administered dose) or oleic acid (1.9% of administered dose) trials. In both the palmitic acid and oleic acid trials, all of the label in stool was identified as being present in the form in which it was administered (i.e. [13C]palmitic acid in the palmitic acid trial and [13C]oleic acid in the oleic acid trial). In contrast, only 87% of the label in the stool in the stearic acid trial was identified as [13C]stearic acid, the remainder was identified as [13C]palmitic acid which may reflect chain shortening of [1-13C]stearic acid within the gastrointestinal tract. Small, but statistically significant, differences were observed in the time course of recovery of 13C label on breath over the initial 9 h of the study period (oleic acid = palmitic acid > stearic acid). However, when calculated over the 24 h study period, the recovery of the label as 13CO2 was similar in all three trials (approximately 25% of absorbed dose). These results support the view that chain length and degree of unsaturation may influence the gastrointestinal handling and immediate metabolic disposal of these fatty acids even when presented within an emulsion.

Adult↗
PubMed1986

Fatty acid-binding protein in liver and small intestine of the preruminant calf.

Cytosol obtained from differential centrifugation of homogenates from liver and small intestine mucosa was incubated with 1-[14C] oleic acid or 1-[14C] palmitic acid and filtered through Sephadex G-75. Elution profiles for both tissues showed radioactivity in two main peaks, the first corresponding to binding of fatty acid to high molecular weight proteins and the second to a protein fraction with a molecular weight of approximately 12,000 daltons. The low molecular weight fraction had high fatty acid-binding activity, which was greater for oleic than palmitic acid. The findings demonstrate the presence of fatty acid-binding protein in liver and intestinal mucosa of the preruminant calf.

Animals↗
PubMed1977

Human amnion metabolism. II. Incorporation of fatty acids into tissue phospholipids in vitro.

The rate of incorporation of 3H-arachidonic acid and 14C-palmitic acid into 15 term amniotic membranes was studied during incubation of tissues in an artificial amniotic fluid medium. Phospholipids were extracted from the amnions, separated by thin-layer chromatography, and both the radioactivity and the phosphorus associated with each phospholipid species were determined. The distribution of amnion phospholipids was: lecithin, 47 per cent; phosphatidyl ethanolamine, 30 per cent; sphingomyelin, 7 per cent; phosphatidyl inositol, 5 per cent; lysolecithin, 4 per cent; and other phospholipids, 6 per cent. During incubation, the specific activities of the phospholipids became maximal after 2 hours and remained constant for at least the next 2 hours. Arachidonic acid was incorporated mainly into lecithin (53 per cent) and phosphatidyl ethanolamine (27 per cent) whereas palmitic acid was incorporated mainly into lecithin (70 per cent). Incorporation of fatty acids was 33 per cent higher in amnions obtained after vaginal delivery than in those obtained before labor. From the known fatty acid composition of amnion phospholipids, it is concluded that there is a high rate of turnover of arachidonic acid relative to palmitic acid in lecithin.

Amnion↗
PubMed2001

A stearic acid-rich diet improves thrombogenic and atherogenic risk factor profiles in healthy males.

OBJECTIVE: To determine whether healthy males who consumed increased amounts of dietary stearic acid compared with increased dietary palmitic acid exhibited any changes in their platelet aggregability, platelet fatty acid profiles, platelet morphology, or haemostatic factors. DESIGN: A randomized cross-over dietary intervention. SUBJECTS AND INTERVENTIONS: Thirteen free-living healthy males consumed two experimental diets for 4 weeks with a 7 week washout between the two dietary periods. The diets consisted of approximately 30% of energy as fat (66% of which was the treatment fat) providing approximately 6.6% of energy as stearic acid (diet S) or approximately 7.8% of energy as palmitic acid (diet P). On days 0 and 28 of each dietary period, blood samples were collected and anthropometric and physiological measurements were recorded. RESULTS: Stearic acid was increased significantly in platelet phospholipids on diet S (by 22%), while on diet P palmitic acid levels in platelet phospholipids also increased significantly (8%). Mean platelet volume, coagulation factor FVII activity and plasma lipid concentrations were significantly decreased on diet S, while platelet aggregation was significantly increased on diet P. CONCLUSION: Results from this study indicate that stearic acid (19g/day) in the diet has beneficial effects on thrombogenic and atherogenic risk factors in males. The food industry might wish to consider the enrichment of foods with stearic acid in place of palmitic acid and trans fatty acids.

Adult↗
PubMed1987

Metabolism in humans of cis-12,trans-15-octadecadienoic acid relative to palmitic, stearic, oleic and linoleic acids.

Mixtures of triglycerides containing deuterium-labeled hexadecanoic acid (16:0), octadecanoic acid (18:0), cis-9-octadecenoic acid (9c-18:1), cis-9,cis-12-octadecadienoic acid (9c, 12c-18:2) and cis-12,trans-15-octadecadienoic acid (12c,15t-18:2) were fed to two young-adult males. Plasma lipid classes were isolated from samples collected periodically over 48 hr. Incorporation and turnover of the deuterium-labeled fats in plasma lipids were followed by gas chromatography-mass spectrometry (GC-MS) analysis of the methyl ester derivatives. Absorption of the deuterated fats was followed by GC-MS analysis of chylomicron triglycerides isolated by ultracentrifugation. Results were the following: (i) endogenous fat contributed about 40% of the total fat incorporated into chylomicron triglycerides; (ii) elongation, desaturation and chain-shortened products from the deuterated fats were not detected; (iii) the polyunsaturated isomer 12c,15t-18:2 was metabolically more similar to saturated and 9c-18:1 fatty acids than to 9c,12c-18:2; (iv) relative incorporation of 9c,12c-18:2 into phospholipids did not increase proportionally with an increase of 9c,12c-18:2 in the mixture of deuterated fats fed; (v) absorption of 16:0, 18:0, 9c-18:1, 9c,12c-18:2 and 12c,15t-18:2 were similar; and (vi) data for the 1- and 2-acyl positions of phosphatidylcholine and for cholesteryl ester fractions reflected the known high specificity of phosphatidylcholine acyltransferase and lecithin:cholesteryl acyltransferase for 9c,12c-18:2. These results illustrate that incorporation of dietary fatty acids into human plasma lipid classes is selectively controlled and that incorporation of dietary 9c,12c-18:2 is limited. These results suggest that nutritional benefits of diets high in 9c,12c-18:2 may be of little value to normal subjects and that the 12c,15t-18:2 isomer in hydrogenated fat is not a nutritional liability at the present dietary level.

Adult↗
PubMed1987

Interaction of trans-parinaric acid with phosphatidylcholine bilayers: comparison with the effect of other fluorophores.

The effect of the fluorophore trans-parinaric acid on the structure of lipid bilayer was studied and compared with the effect of other 'perturbants'. These include commonly used fluorophores (diphenylhexatriene, heptadecylhydroxycoumarin, cis-parinaric acid and two fatty acids, palmitic and oleic acids). Differential scanning calorimetry (DSC) and proton nuclear magnetic resonance techniques were used to evaluate structural changes in the lipid bilayers. The thermodynamic parameters of dipalmitoylphosphatidylcholine multilamellar vesicles obtained from the DSC thermograms suggest that trans-parinaric acid differs from the other 'perturbants'. trans-Parinaric acid has the most pronounced impact on the Tm, the width (delta T1/2) and the index of asymmetry of the main gel to liquid crystalline phase transition without any effect on its transition, delta H. The presence of trans-parinaric acid in the lipid bilayer of dimyristoylphosphatidylcholine small unilamellar vesicles influences the chemical shift difference between the choline protons of phosphatidylcholine molecules present in the two leaflets of the vesicle bilayer (delta delta H). This suggests that trans-parinaric acid affects the head group packing in the bilayer. Its main effect is abolishing the major alterations in head group packing that occur through the phase transition. The above data indicate that trans-parinaric acid is concentrated in the gel phase domains, whereby it stabilizes the phase separation between the gel and liquid crystalline phases, probably by affecting lipid molecules present in the boundary regions between these two domain types.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

Fatty acids and cholesterol: effect on the interaction of theophylline with bovine serum albumin.

The binding of theophylline (Th, 11-840 microM) to bovine serum albumin (BSA, 10 microM) using microdialysis technique in the presence of fatty acids (2.5-50.0 microM) and cholesterol (20-500 nM) indicates that fatty acids and cholesterol inhibit the binding of Th to BSA. The maximum inhibition (90.5%) occurs in presence of acetic acid (AA) followed by lauric acid (LA, 83.3%), palmitic acid (PA, 72.2%), oleic acid (OA, 44.4%) and cholesterol (22.2%). Fatty acids and cholesterol also decrease the number of binding sites and the affinity for the binding of Th to BSA. Such a decrease is maximum in the presence of AA followed by LA, PA, OA and cholesterol. Complete abolition of the low affinity binding site in the presence of AA indicates that the low affinity binding is predominantly ionic in nature while the high affinity binding involves ionic and other type(s) of unidentified force(s). This makes high affinity binding stronger than low affinity binding.

Acetates↗
PubMed1996

Chronic heat exposure enhances fat deposition and modifies muscle and fat partition in broiler carcasses.

The effect of chronic heat exposure on carcass quality of broilers: proportion of lean and fat tissues, fat content, and fatty acid composition, was investigated. One hundred and eight 4-wk-old male chickens were brooded in individual battery cages in two controlled-environment rooms at constant ambient temperature (22 or 32 C) until 7 wk of age. They were equally distributed into three treatments: 22 C, ad libitum feeding (22AL); 32 C, ad libitum feeding (32AL); and 22 C, pair-feeding on the daily feed intake of heat-exposed chickens (22PF). At 7 wk of age, heat-exposed chickens (32AL) had a lower body weight gain than the other birds: -47% compared to 22AL and -31% compared to 22PF. At 32 C, broilers exhibited a lower breast to body weight proportion: 11.9 vs 13.4% for 22AL. Abdominal, subcutaneous, and intermuscular fat deposits were enhanced in hot conditions, respectively, 15, 21, and 22% compared to 22AL and 58, 64, and 33% compared to 22PF. However, lipid contents of abdominal, subcutaneous, intermuscular, and intramuscular tissues were not affected by heat exposure but were significantly reduced in the 22PF birds. In heat-exposed birds, although saturated fatty acid proportions, particularly palmitic acid (C16:0), were increased, unsaturated fatty acids as a percentage of total fatty acids were decreased, especially oleic (C18:1) and linoleic (C18:2) acids in fat tissues. Consequently, under ad libitum feeding conditions, heat exposure significantly decreased the unsaturated to saturated fatty acid ratio in the abdominal and subcutaneous fat tissues, but not in intermuscular and intramuscular fats.

Adipose Tissue↗
PubMed1980

[Puromycin action on intestinal lipid absorption in male and female rats].

The effect of puromycin on absorption balance and mucosal lipid distribution was studied during intestinal absorption of 14C oleic acid and 3H palmitic acid, using the isolated intestinal loop of male and female rats in situ. In puromycin-treated animals, mucosal lipid uptake was reduced and mucosal lipid content increased, particularly with oleic acid and in male rats. The phospholipids were significantly reduced. As revealed by mucosal accumulation of free fatty acids, esterification was particularly inhibited with oleic acid and in female rats. These results might explain why portal blood radioactivity was higher in treated rats than in the controls. Puromycin effect occurred at different stages of lipid absorption and varied with sex.

Animals↗
PubMed1992

Fatty acid monooxygenation by P450BM-3: product identification and proposed mechanisms for the sequential hydroxylation reactions.

The soluble P450 isolated from Bacillus megaterium (the product of the CYP 102 gene) (P450BM-3) is a catalytically self-sufficient fatty acid hydroxylase which converts lauric, myristic, and palmitic acids to omega-1, omega-2, and omega-3 hydroxy analogs. The percentage distribution of the regioisomers depends on the substrate chain length. Lauric and myristic acids were preferentially metabolized to their omega-1 hydroxy counterparts while no hydroxylation occurred when capric acid was used as the substrate. Palmitic acid, when present at concentrations greater than the concentration of oxygen in the reaction medium (greater than 250 microM), was hydroxylated to its omega-1, omega-2, and omega-3 hydroxy analogs, with the percentage distribution of the regioisomers being 21:44:35, respectively. No omega hydroxylation of any of the fatty acids was detected. When the concentration of palmitic acid was less than the concentration of oxygen in the reaction mixture, it was noted that a number of additional products were formed. Under these conditions, unlike lauric and myristic acids, it was observed that palmitic acid was first converted to its monohydroxy isomers which were subsequently metabolized to a mixture of 14-ketohexadecanoic, 15-ketohexadecanoic, 13-hydroxy-14-ketohexadecanoic, 14-hydroxy-15-ketohexadecanoic, and 13,14-dihydroxyhexadecanoic acids with a relative distribution of 8:2:40:30:20, respectively. Thus, P450BM-3 is able not only to monohydroxylate a variety of fatty acids but also to further metabolize some of these primary metabolites to secondary and tertiary products. The present paper characterizes the products formed during the sequential hydroxylation of palmitic acid and proposes reaction pathways to explain these results.

Bacillus megaterium↗
PubMed1985

Studies on the uptake of fatty acids by brush border membranes of the rabbit intestine.

Initial studies revealed that the uptake of palmitic acid and oleic acid into brush border membranes was similar when these were isolated from either whole small intestine, jejunum, or ileum. The uptake of these fatty acids was somewhat lower with membranes obtained from duodenum. Subsequent studies, all with membranes obtained from whole intestine, indicated an increase in binding with chain length of fatty acid of up to 16 carbons. Unsaturation decreased this uptake somewhat. Taurocholate and 1-palmitoyl lysolecithin had a moderate stimulatory effect on the binding of oleic acid and palmitic acid at concentrations of 10 and 0.5 mM, respectively, and inhibited at higher concentrations. Addition of 1.4 mM egg lecithin to the fatty acid - bile salt micelles, such that the lecithin - bile salt ratio was 0.2, decreased the uptake of fatty acids generally, but did not significantly affect the pattern of binding by membrane fractions isolated from different segments nor did it change the pattern of labelling when fatty acid chain length and unsaturation were varied. At lower concentrations, egg lecithin had little effect on the uptake of oleic acid, whereas dipalmitoyl phosphatidylcholine stimulated binding of both palmitic acid and oleic acid over the entire range of concentrations tested. Preincubation of the membranes with this saturated phospholipid stimulated the uptake of oleic acid, and addition of this choline lipid to the oleic acid - bile salt containing micelles did not substantially enhance fatty acid uptake in lipid-treated membranes. The binding of fatty acid was very rapid either in the presence or the absence of Ca2+, such that even in zero-time controls essentially equilibrium bindings were obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

[Mode of fatty acid synthesis in rat liver mitochondria (author's transl)].

In order to clarify the mode of fatty acid synthesis in rat liver mitochondria, metabolism of labeled fatty acid was examined after portal and intraperitoneal administration of several labeled fatty acids. 1) After portal administration of palmitic acid-1-14C, alpha, beta-mono-unsaturated fatty acid (C18:1) was synthesized as a result of chain elongation by addition of endogenous C2 compound 20 min. after injection. 2) Similarly, after lauric acid-1-14C injection, myristic acid (C14) and palmitic acid (C16) were found 20 min. after injection and even C18:2 was detected 30 min. after injection. 3) Following intraperitoneal administration of lauric acid-1-14C, the appearance of palmitic acid (C16) was confirmed in inner mitochondrial membranes 60 min. after injection. From the analysis of intramolecular distribution of labeled carbon, it is surmised that lauric acid is first decomposed into C2 fragments which then are used for the chain elongation.

Animals↗
PubMed2001

Thioacylation is required for targeting G-protein subunit G(o1alpha) to detergent-insoluble caveolin-containing membrane domains.

alpha-Subunits of heterotrimeric G(i)-like proteins (alpha(i), alpha(o) and alpha(z)) associate with the cytoplasmic leaflet of the plasma membrane by means of N-terminally linked myristic acid and palmitic acid. An additional role for palmitate has been recently suggested by the observation that fusion with the palmitoylated N-terminus of alpha(i1) relocalizes cytosolic green-fluorescent-protein reporter to low buoyancy, Triton-insoluble membrane domains (TIFF; Triton-insoluble floating fraction), enriched with caveolin-1 [Galbiati, Volonté, Meani, Milligan, Lublin, Lisanti and Parenti (1999) J. Biol. Chem 274, 5843-5850]. Here we show that, upon transient expression in transfected COS-7 cells, myristoylated and palmitoylated alpha(o) (alpha(o)wt, where wt is wild-type) is exclusively found in TIFF, from where non-palmitoylated alpha(o)wt and alpha(o)C3S (Cys(3)-->Ser) mutant are excluded. Moreover, alpha(o) fused to N-terminally truncated human vasopressin V2 receptor (V2TR-alpha(o)), lacking myristate and palmitate, still localizes at the plasma membrane by means of first transmembrane helix of V2R, but is excluded from TIFF. Likewise, alpha(o)C3S does not partition into TIFF, even when its membrane avidity is enhanced by co-expression of betagamma-subunits. Thus membrane association, in the absence of added palmitate, is not sufficient to confer partitioning of alpha(o) within TIFF, suggesting that palmitoylation is a signal for membrane compartmentalization of dually acylated alpha-subunits.

Acylation↗
PubMed2000

Extracellular release of free fatty acids by rat T lymphocytes is stimulus-dependent and is affected by dietary lipid manipulation.

[(3)H]-Arachidonic acid-labelled rat T lymphocytes released radioactivity extracellularly when stimulated by the calcium ionophore A23187 or by monoclonal antibodies to some cell surface structures (CD2, CD5, CD11a, CD18, CD54, T-cell receptor) but not to others (CD49d, CD62L); release was greater with the calcium ionophore. Almost all of the radioactivity released from anti-CD2-stimulated lymphocytes was recovered in the free fatty acid fraction, whereas only about 50 per cent of that released after A23187 stimulation was recovered in this fraction. A23187 stimulation resulted in release of arachidonic acid from a variety of phospholipids (phosphatidylinositol, phosphatidylcholine and perhaps phosphatidylethanolamine), while the monoclonal antibody stimulation released arachidonic acid from phosphatidylinositol and perhaps phosphatidylcholine. Unstimulated lymphocytes released a range of fatty acids extracellularly, with palmitic acid accounting for 35-40 per cent and arachidonic acid for 5 per cent of released fatty acid. Stimulation of lymphocytes with either anti-CD2 or A23187 increased total fatty acid release 1.5- to 1.8-fold. In both cases palmitic acid remained the most predominant fatty acid released but the contribution of arachidonic acid increased. The type of lipid fed to the rats significantly influenced the amount and type of fatty acid released. Fish oil feeding significantly reduced extracellular fatty acid release by stimulated lymphocytes.

Animals↗
PubMed1993

Effects of the individual saturated fatty acids on serum lipids and lipoprotein concentrations.

A mixture of dietary saturated fatty acids raises the serum total cholesterol concentrations compared with a diet of isoenergetic amounts of carbohydrates. Saturated fatty acids are not all equally hypercholesterolemic: stearic acid (18:0) and saturated fatty acids with < 12 carbon atoms are thought not to raise serum cholesterol concentrations. This suggest that the cholesterol-raising properties of saturated fatty acids should be attributed solely to lauric acid (12:0), myristic acid (14:0), and palmitic acid (16:0). These three saturated fatty acids, however, may have different effects on serum total-cholesterol concentrations as well. Results from controlled dietary experiments suggest that lauric acid (12:0) is less, and myristic acid (14:0) probably more, hypercholesterolemic than palmitic acid (16:0). Effects of the different saturated fatty acids on the distribution of cholesterol over the various lipoproteins are largely unknown, but it is suggested that stearic acid lowers HDL cholesterol concentrations relative to other saturated fatty acids. At present, however, too many questions are unanswered to quantitate these differences.

Cholesterol↗