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PubMed2001

Inhibition and regulation of rat liver L-threonine dehydrogenase by different fatty acids and their derivatives.

Rat liver L-threonine dehydrogenase is a mitochondrial enzyme which transforms L-threonine either into aminoacetone or into acetyl-CoA. We show that it is inhibited by several fatty acids and their derivatives: short chain fatty acids, L-2-hydroxybutyrate and D-3-hydroxybutyrate, long chain fatty acids, such as lauric acid, myristic acid, palmitic and stearic acids, bicarboxylic acids such as malonic acid and its derivatives methyl- and hydroxymalonic acids. The inhibition occurs at low and physiological concentrations of such compounds, which are normally present and metabolized in mitochondria. It presumably plays a role in the physiology of acetyl-CoA-dependent formation of fatty acids and ketobodies, in L-threonine-dependent gluconeogenesis, and in the regulation of L-threonine metabolism by L-threonine dehydrogenase and L-threonine deaminase.

3-Hydroxybutyric Acid↗
PubMed1999

Lipids, lipoproteins, and fatty acids during infantile marasmus in the Fès area of Morocco.

The lipid composition of plasma, including total HDL and LDL cholesterol, triglycerides, apo AI, apo B, and fatty acids was investigated in 29 malnourished Moroccan children in two groups: 12 children with mild PCM, and 17 with severe PCM. Normally nourished children from the same area (n = 15) served as controls. The severe malnourished children showed a significant reduction of apo AI, total and LDL cholesterol, and an increase in the levels of triglycerides. Furthermore, these children showed a decrease in the saturated fatty acids myristic and stearic acid, and a similar decrease in the essential fatty acid (EFA) metabolites, especially eicosatrienoic acid, arachidonic acid, and eicosapentaenoic acid, with an increase in the oleic and cisvaccenic monounsaturated fatty acids. In contrast, the PCM group showed only an increase of docosatetraenoic and docosapentaenoic, with an associated decrease in myristic acid and palmitic acid. On the other hand, the indexes of delta 9 desaturase and elongase n-3 and n-6 were increased, and this was found to be related to the severity of the malnutrition. These results suggest that the severity of malnutrition is associated with an increase of desaturation and elongation of PUFA, EFA deficiency and/or peroxidation.

Age Factors↗
PubMed1997

Stable nitroxide radicals protect lipid acyl chains from radiation damage.

The present study focused on protective activity of two six-membered-ring nitroxide radicals, 2,2,6,6-tetramethylpiperidine-1-oxyl (Tempo) and 4-hydroxy-Tempo (Tempol), against radiation damage to acyl chain residues of egg phosphatidylcholine (EPC) of small unilamellar vesicles (SUV). SUV were gamma-irradiated (10-12 kGy) under air at ambient temperature in the absence and presence of nitroxides. Acyl chain composition of the phospholipids before and after irradiation was determined by gas chromatography. Both Tempo and Tempol effectively and similarly protected the acyl chains of EPC SUV, including the highly sensitive polyunsaturated acyl chains, C20:4, C22:5, and C22:6. The conclusions of the study are: (a) The higher the degree of unsaturation in the acyl chain, the greater is the degradation caused by irradiation. (b) The fully saturated fatty acids palmitic acid (C16) and stearic acid (C18) showed no significant change in their levels. (c) Both Tempo and Tempol provided similar protection to acyl chain residues. (d) Nitroxides' lipid-bilayer/aqueous distribution is not validly represented by their n-octanol/saline partition coefficient. (e) The lipid-bilayer/aqueous partition coefficient of Tempo and Tempol cannot be correlated with their protective effect. (f) The nitroxides appear to protect via a catalytic mode. Unlike common antioxidants, such as alpha-tocopherol, which are consumed under irradiation and are, therefore, less effective against high radiation dose, nitroxide radicals are restored and terminate radical chain reactions in a catalytic manner. Furthermore, nitroxides neither yield secondary radicals upon their reaction with radicals nor act as prooxidants. Not only are nitroxides self-replenished, but also their reduction products are effective antioxidants. Therefore, the use of nitroxides offers a powerful strategy to protect liposomes, membranes, and other lipid-based assemblies from radiation damage.

Antioxidants↗
PubMed2001

Effects of addition of hydrophobic sucrose fatty acid oligoesters on crystallization rates of n-hexadecane in oil-in-water emulsions.

Ultrasonic velocity measurements were made on crystallization rates of n-hexadecane dispersed in an oil-in-water (O/W) emulsion (20 wt.% oil and 80 wt.% water) in which Tween 20 was employed for emulsification. Highly hydrophobic emulsifiers, sucrose fatty acid oligoesters involving stearic acid (S-170), lauric acid (L-195) and oleic acid (O-170) moieties, were added to n-hexadecane in an attempt to modify the crystallization rate of n-hexadecane. The crystallization process of n-hexadecane was monitored by variations in the ultrasonic velocity values, which increase with increasing amount of crystal fractions in the oil phase of the emulsion. In comparison with the results of the O/W emulsion systems with the additive P-170 (a sucrose palmitate) (N.Kaneko et al., J. Crystal Growth 197 (1999) 263), the following results were obtained: (a) the addition of S-170 accelerated the nucleation in the emulsion system in the same manner as P-170, no acceleration was revealed with the additive O-170, and L-195 showed moderate effects; (b) the rate of crystal growth was retarded by S-170 and L-195, but not by O-170; (c) the effects of acceleration of nucleation occurred singly in the emulsion system, but not in the bulk system; and (d) the acceleration of nucleation was exhibited through two stages with increasing concentrations of the additives. These results showed the remarkable influence of the fatty acid chain structures of sucrose oligoesters on the acceleration of heterogeneous nucleation of n-hexadecane in the O/W emulsions. The heterogeneous nucleation effected by the addition of S-170 and P-170 was discussed taking into account the adsorption at the oil-water interface and the formation of reversed micelles of the sucrose oligoesters added in the oil phase.

Journal Article↗
PubMed1997

Oleic acid-induced Ca2+ mobilization in human platelets: is oleic acid an intracellular messenger?

The purpose of this study was to explore the effect of oleic acid (OA) on intracellular Ca2+ mobilization in human platelets. When applied extracellularly, OA produced a concentration dependent rise in cytosolic [Ca2+] ([Ca2+]cyt) when extracellular [Ca2+] (Ca2+]ext) was zero (presence of EGTA), suggesting that OA caused an intracellular release of Ca2+. Intracellular Ca2+ release was directly proportional to entry of OA into platelets and OA entry was indirectly proportional to [Ca2+]ext. In permeabilized platelets, OA caused the release of 45Ca2+ from ATP dependent intracellular stores. Finally, our results show that thrombin stimulated the release of [3H]OA from platelet phospholipids. The saturated fatty acids stearic and palmitic acid did not stimulate an increase in [Ca2+]cyt under these conditions, but the unsaturated fatty acid, linolenic acid produced effects similar to those of OA, suggesting specificity among fatty acids for effects on [Ca2+]cyt. Taken together, our experiments suggest that OA which has been incorporated into platelet phospholipids was released into the cytosol by thrombin stimulation. Our experiments also show that OA stimulates Ca2+ release from intracellular stores. These results support the hypothesis that OA may serve as an intracellular messenger in human platelets.

Blood Platelets↗
PubMed2000

Myristic acid, unlike palmitic acid, is rapidly metabolized in cultured rat hepatocytes.

This study was designed to examine and compare the metabolism of myristic and palmitic acids in cultured rat hepatocytes. [1-(14)C]-Labeled fatty acids were solubilized with albumin at 0.1 mmol/L in culture medium. Incubation with 24-hr cultured hepatocytes was carried out for 12 hr. Myristic acid was more rapidly (P < 0.05) taken up by the cells than was palmitic acid (86.9 +/- 0.9% and 68.3 +/- 5.7%, respectively, of the initial radioactivity was cleared from the medium after 4 hr incubation). Incorporation into cellular lipids, however, was similar after the same time (33.4 +/- 2.8% and 34.9 +/- 9.3%, respectively, of initial radioactivity). In the early phase of the incubation (30 min), myristic acid was more rapidly incorporated into cellular triglycerides than was palmitic acid (7.4 +/- 0.9% and 3.6 +/- 1.9%, respectively, of initial radioactivity). However, after 12 hr incubation, the radioactivity of cellular triglycerides, cellular phospholipids, and secreted triglycerides was significantly higher with palmitic acid as precursor. Myristic acid oxidation was significantly higher than that of palmitic acid (14.9 +/- 2.2% and 2.3 +/- 0.6%, respectively, of the initial radioactivity was incorporated into the beta-oxidation products after 4 hr). Myristic acid was also more strongly elongated to radiolabeled palmitic acid (12.2 +/- 0.8% of initial radioactivity after 12 hr) than palmitic acid was to stearic acid (5.1 +/- 1.3% of initial radioactivity after 12 hr). The combination of elongation and beta-oxidation results in the rapid disappearance of C14:0 in hepatocytes whereas C16:0 is esterified to form glycerolipids. This study provides evidence that myristic acid is more rapidly metabolized in cultured hepatocytes than is palmitic acid.

Journal Article↗
PubMed2002

Effect of season on the fatty acid composition and free amino acid content of the sardine Sardinops melanostictus.

The purpose of this study was to clarify the seasonal variation of fatty acid composition and free amino acid content in the Japanese sardine (Sardinops melanostictus) from the sea of Hyuga-Nada, and the relationship between the fatty acid composition of this sardine and that of plankton in the area. The lipid content of sardines at the sea of Hyuga-Nada was low in February (1.8%) and high (7.2%) from July to September. The major fatty acids in the total lipids from sardine were myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), palmitoleic acid (16:1 n-7), oleic acid (18:1 n-9), eicosapentaenoic acid (20:5 n-3), and docosahexaenoic acid (22:6 n-3). The characteristics of the fatty acids isolated from sardines in July were similar to those from plankton in the same season. This reflects the deposition of plankton fatty acids in sardine depot fat. The season of high free histidine content in the ordinary meat corresponded with that of high lipid content. These results suggested that both the fatty acid composition of sardines and the high concentrations of certain amino acids in free form are influenced by the intake and seasonal variation of composition of plankton.

Amino Acids↗
PubMed2002

Addition of protected and unprotected fish oil to diets for dairy cows. I. Effects on the yield, composition and taste of milk.

Thirty Holstein cows in mid-lactation (158+/-20 DIM) were given a total mixed ration based on grass silage, maize silage and rolled barley. After a preliminary period of 1 week, this diet was supplemented with nothing (control), unprotected fish oil (3.7% of dry matter, DM), or two levels of glutaraldehyde-protected microcapsules of fish oil (1.5% and 3.0% of DM, respectively). Unprotected and protected supplements contained, respectively, 74% and 58% of DM as lipids. Cows given the unprotected supplement reduced their feed intake by > 25%. Consequently, these cows lost body weight and produced less milk. DM intake, body weight, and milk yield were unaffected by protected fish oil. Fish oil reduced both milk fat and protein percentages, and decreased the proportion of short-chain fatty acids, stearic, and oleic acids in milk fat. Milk trans C18:1 fatty acids increased in cows given both unprotected and protected fish oil. Milk fat content of very-long-chain n3 polyunsaturated fatty acids, including C20:5 and C22:6, increased with fish oil in the diet. Accordingly, the peroxide index increased and a taste panel was able to detect unusual taste in milk from cows consuming the higher level of protected fish oil and disliked the milk from cows given unprotected fish oil. In conclusion, when lactating cows consumed fish oil, milk concentration of long-chain n3 fatty acids increased and mammary de novo synthesis of fatty acids decreased, but milk yield and milk protein content were reduced, and the milk was more susceptible to oxidation and its taste was adversely affected.

Animals↗
PubMed1998

Determination of total long-chain fatty acids in human plasma and lipoproteins, before and during copper-stimulated oxidation, by high-performance liquid chromatography.

An improved method for the high-performance liquid chromatographic determination (HPLC) of total or free long-chain (> C12) fatty acids in small volumes (10 microL) of human plasma and lipoprotein samples is described. The method is based on the formation of 2-nitrophenyl-hydrazine (2-NPH) derivatives and offers an alternative to gas chromatographic (GC) fatty acid determination. The retention of 2-NPH fatty acid derivatives on the HPLC system differs from the typical pattern produced by GC separation, thus offering a powerful tool for confirmation of peak identification where GC peak resolution is poor. Fatty acids determined include saturates [myristic acid, C14:0; palmitic acid, C16:0; stearic acid, C18:0; eicosanoic acid, C20:0; docosanoic acid, C22:0; and tetracosanoic acid, C24:0], monounsaturates [palmitoleic, C16:1; petroselenic, C18:1n12; oleic, C18:1n9; and erucic, C22:1], and polyunsaturates [linoleic, C18:2; linolenic, C18:3n3; gamma-linolenic acid, C18:3n6; eicosatrienoic, C20:3; arachidonic, C20:4; eicosapentanoic, C20:5; docosahexanoic, C20:6; and docosatetraenoic, C22:4]. Mean recoveries of fatty acids added to LDL samples were 94.1-109.4%, and intraassay coefficients of variation for the major fatty acids in human plasma were 2.7-6.9%. The potential of the method for further development is discussed. Long-chain fatty acid profiles are given for plasma and very low-, low, and high-density lipoprotein (before and during copper-stimulated oxidation) from human blood.

Chromatography, High Pressure Liquid↗
PubMed1987

Spin-label electron spin resonance study of bacteriophage M13 coat protein incorporation into mixed lipid bilayers.

The major coat protein of bacteriophage M13 was incorporated in mixed dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (80/20 w/w) vesicles probed with different spin-labeled phospholipids, labeled on the C-14 atom of the sn-2 chain. The specificity for a series of phospholipids was determined from a motionally restricted component seen in the electron spin resonance (ESR) spectra of vesicles with the coat protein incorporated. At 30 degrees C and pH 8, the fraction of motionally restricted phosphatidic acid spin-label is 0.36, 0.52, and 0.72 for lipid/protein ratios of 18, 14, and 9 mol/mol, respectively. The ESR spectra, analyzed by digital subtraction, resulted in a phospholipid preference following the pattern cardiolipin = phosphatidic acid greater than stearic acid = phosphatidylserine = phosphatidylglycerol greater than phosphatidylcholine = phosphatidylethanolamine. The specificities found are related to the composition of the target Escherichia coli cytoplasmic membrane.

Coliphages↗
PubMed2003

Oil goldenberry (Physalis peruviana L.).

Whole berries, seeds, and pulp/peel of goldenberry (Physalis peruviana L.) were compared in terms of fatty acids, lipid classes, triacylglyerols, phytosterols, fat-soluble vitamins, and beta-carotene. The total lipid contents in the whole berries, seeds, and seedless parts were 2.0, 1.8, and 0.2% (on a fresh weight basis), respectively. Linoleic acid was the dominating fatty acid followed by oleic acid as the second major fatty acid. Palmitic and stearic acids were the major saturates. In pulp/peel oil, the fatty acid profile was characterized by higher amounts of saturates, monoenes, and trienes than in whole berry and seed oils. Neutral lipids comprised >95% of total lipids in whole berry oil and seed oil, while neutral lipids separated in lower level in pulp/peel oil. Triacylglycerols were the predominant neutral lipid subclass and constituted ca. 81.6, 86.6, and 65.1% of total neutral lipids in whole berry, seed, and pulp/peel oils, respectively. Nine triacylglycerol molecular species were detected, wherein three species, C54:3, C52:2, and C54:6, were presented to the extent of approximately 91% or above. The highest level of phytosterols was estimated in pulp/peel oil that contained the highest level of unsaponifiables. In both whole berry and seed oils, campesterol and beta-sitosterol were the sterol markers, whereas Delta5-avenasterol and campesterol were the main 4-desmethylsterols in pulp/peel oil. The tocopherols level was much higher in pulp/peel oil than in whole berry and seed oils. beta- and gamma-tocopherols were the major components in whole berry and seed oils, whereas gamma- and alpha-tocopherols were the main constituents in pulp/peel oil. beta-Carotene and vitamin K(1) were also measured in markedly high levels in pulp/peel oil followed by whole berry oil and seed oil, respectively. Information provided by the present work is of importance for further chemical investigation of goldenberry oil and industrial utilization of the berries as a raw material of oils and functional foods.

Fatty Acids↗
PubMed2005

Effect of dietary fatty acids on the postprandial fatty acid composition of triacylglycerol-rich lipoproteins in healthy male subjects.

OBJECTIVE: The aim of the present study was to investigate the effect of trans-18:1 isomers compared to other fatty acids, especially saturates, on the postprandial fatty acid composition of triacylglycerols (TAG) in chylomicrons and VLDL. DESIGN: A randomised crossover experiment where five interesterified test fats with equal amounts of palmitic acid (P fat), stearic acid (S fat), trans-18:1 isomers (T fat), oleic acid (O fat), or linoleic acid (L fat) were tested. SUBJECTS: A total of 16 healthy, normolipidaemic males (age 23+/-2 y) were recruited. INTERVENTIONS: The participants ingested fat-rich test meals (1 g fat per kg body weight) and the fatty acid profiles of chylomicron and VLDL TAG were followed for 8 h. RESULTS: The postprandial fatty acid composition of chylomicron TAG resembled that of the ingested fats. The fatty acids in chylomicron TAG were randomly distributed among the three positions in accordance with the distributions in test fats. Calculations of postprandial TAG concentrations from fatty acid data revealed increasing amounts up to 4 h but lower response curves (IAUC) for the two saturated fats in accordance with previous published data. The T fat gave results comparable to the O and L fats. The test fatty acids were much less reflected in VLDL TAG and there was no dietary influence on the response curves. CONCLUSIONS: The fatty acid composition in the test fats as well as the positional distributions of these were maintained in the chylomicrons. No specific clearing of chylomicron TAG was observed in relation to time.

Adult↗
PubMed1980

Fat metabolism in heavy exercise.

1. To investigate differences between the metabolic effects of light and heavy exercise, five healthy males (mean maximal oxygen intake 3.92 litres/min) exercised for 40 min at 36% maximum power (light work) and 70% maximum power (heavy work) on separate days, after an overnight fast. 2. A steady state was achieved in both studies between 20 and 40 min in: oxygen intake (1.42 and 2.64 litres/min respectively); respiratory exchange ratio (0.89 and 1.01); plasma lactate concentration (1.78 and 9.94 mmol/l). 3. Plasma palmitate turnover rate (14C) was unchanged from resting values in light work but was decreased by 40% (from 104 +/- 16 to 63 +/- 8 micronml/min) in heavy work. Heavy work was associated with falls in the plasma concentrations of all free fatty acids measured: palmitic acid (C16:0), oleic acid (C18:1), stearic acid (C18:0), linoleic acid (C18:2) and palmitoleic acid (C16:1). 4. In contrast to th fall in palmitate turnover the increase in plasma glycerol was greater in heavy exercise (0.054-0.229 mmol/l) than in light exercise (0.053-0.094 mmol/l), suggesting that lipolysis was occurring which did not lead to influx of free fatty acids into plasma. 5. In light exercise fat metabolism may be controlled to favour adipose tissue lipolysis and extraction of free fatty acids by muscle from the circulation, whereas in heavy exercise adipose tissue lipolysis is inhibited and hydrolysis of muscle triglycerides may play a more important part. 6. The finding of a high respiratory exchange ratio may not exclude the use of fat as a major fuel source in exercise associated with lactate production.

Adult↗
PubMed2006

Fatty acid esters of 3-chloropropane-1,2-diol in edible oils.

A series of 25 virgin and refined edible oils, obtained from retailers, was analyzed for levels of free 3-chloropropane-1,2-diol (3-MCPD) and 3-MCPD released from esters with higher fatty acids (bound 3-MCPD). Oils containing free 3-MCPD ranging from <3 microg kg-1 (LOD) to 24 microg kg-1. Surprisingly, bound 3-MCPD levels were much higher and varied between <100 (LOD) and 2462 microg kg-1. On average, virgin oils had relatively low levels of bound 3-MCPD, ranging from <100 (LOD) to <300 microg kg-1 (LOQ). Higher levels of bound 3-MCPD were found in oils from roasted oilseeds (337 microg kg-1) and in the majority of refined oils (<300-2462 microg kg-1), including refined olive oils. In general, it appears that the formation of bound 3-MCPD in oils is linked to preliminary heat treatment of oilseeds and to the process of oil refining. Analysis of unrefined, de-gummed, bleached, and deodorized rapeseed oil showed that the level of bound MCPD decreased during the refining process. However, additional heating of seed oils for 30 min at temperatures ranging from 100 to 280 degrees C, and heating at 230 degrees C (260 degrees C) for up to 8 h, led to an increase in bound 3-MCPD levels. On the other hand, heating of olive oil resulted in a decrease in bound 3-MCPD levels. For comparison, fat isolated from salami was analyzed for intact fatty acid esters of 3-MCPD. This fat contained bound 3-MCPD at a level of 1670 microg kg-1 and the fatty acid esters of 3-MCPD mainly consisted of 3-MCPD diesters; monoesters of 3-MCPD were present in smaller amounts. The major types of 3-MCPD diesters (about 85%) were mixed diesters of palmitic acid with C18 fatty acids (stearic, oleic, linoleic acids). These diesters were followed by 3-MCPD distearate (11%) and 3-MCPD dipalmitate (4%). Generally, very little 3-MCPD existed as the free compound (31 microg kg-1).

Esters↗
PubMed2001

Final report on the safety assessment of Octyidodecyl Stearoyl Stearate.

Octyldodecyl Stearoyl Stearate functions as an occlusive skin-conditioning agent and as a nonaqueous viscosity-increasing agent in many cosmetic formulations. Current concentrations of use are between 0.7% and 23%, although historically higher concentrations were used. The chemical is formed by a high-temperature, acid-catalyzed esterification reaction of long-chain alcohols (primarily C-20) and a mixture of primarily C-18 fatty acids. Levels of stearic acid, octyldodecanol, and octylydocecyl hydroxystearate in the final product are 5% or less--no other residual compounds are reported. Only limited safety test data were available on Octyldodecyl Stearoyl Stearate, but previous safety assessments of long-chain alcohols and fatty acids found these precursors to be safe for use in cosmetic formulations. Octyldodecyl Stearoyl Stearate produced no adverse effects in acute exposures in rats. The chemical was mostly nonirritating to animal skin at concentrations ranging from 7.5% to 10%; one study did find moderate irritation in rabbit skin at a concentration of 7.5%. Clinical tests at a concentration of 10.4% confirmed the absence of significant irritation in humans. An ocular toxicity study in rabbits found no toxicity. No evidence of genotoxicity was found in either a mammalian test system or in the Ames test system, with or without metabolic activation. The available data on Octyldodecyl Stearoyl Stearate and the previously considered data on long-chain alcohols and fatty acids, however, did not provide a sufficient basis to make a determination of safety. Additional data needs include (1) chemical properties, including the octanol/water partition coefficient; and (2) if there is significant dermal absorption or if significant quantities of the ingredient may contact mucous membranes or be ingested, then reproductive and developmental toxicity data may be needed. Until such time as these data are received, the available data do not support the safety of Octyldodecyl Stearoyl Stearate as used in cosmetic formulations.

Animals↗
PubMed2004

Polyunsaturated fatty acids are FXR ligands and differentially regulate expression of FXR targets.

Polyunsaturated fatty acids (PUFAs) have been previously reported as agonists of peroxisome proliferatoractivated receptor and antagonists of the liver X receptor. The activities on these two nuclear receptors have been attributed to their beneficial effects such as improvement of dyslipidemia and insulin sensitivity and decrease of hepatic lipogenesis. Here we report that PUFAs are ligands of farnesoid X receptor (FXR), a nuclear receptor for bile acids. In a conventional FXR binding assay, arachidonic acid (AA, 20:4), docosahexaenoic acid (DA, 22:6), and linolenic acid (LA, 18:3) had an affinity of 2.6, 1.5, and 3.5 microM, respectively. In a cell-free coactivator association assay, AA, DA, and LA decreased FXR agonist-induced FXR activation with IC(50)s ranging from 0.9 to 4.7 microM. In HepG2 cells, PUFAs regulated the expression of two FXR targets, BSEP and kininogen, in an opposite fashion, although both genes were transactivated by FXR. All three PUFAs dose-dependently enhanced FXR agonist-induced BSEP expression but decreased FXR agonist-induced human kininogen mRNA. Saturated fatty acids such as stearic acid (SA, 18:0) and palmitic acid (PA, 16:0) did not bind to FXR and did not change BSEP or kininogen expression. The pattern of BSEP and kininogen regulation by PUFAs is closely similar to that of the guggulsterone, previously reported as a selective bile acid receptor modulator. Our results suggest that PUFAs may belong to the same class of FXR ligands as guggulsterone, and that the selective regulation of FXR targets may contribute to the beneficial effects of PUFAs in lipid metabolism.

ATP-Binding Cassette Transporters↗
PubMed1998

Change in dietary saturated fat intake is correlated with change in mass of large low-density-lipoprotein particles in men.

We tested whether nutrient intakes estimated from 4-d diet records were associated with plasma lipoprotein subclasses in 103 men who were randomly assigned to a low-fat (24% fat) and a high-fat (46% fat) diet for 6 wk each in a crossover design. Postheparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activities were also determined in a subset of 43 men. Changes in intake (ie, high fat minus low fat) of total saturated fatty acids, as well as myristic (14:0) and palmitic (16:0) acids, were positively correlated (P < 0.01) with increases in mass of large LDL particles [measured by analytic ultra-centrifugation as mass of lipoproteins of flotation rate (Sf) 7-12] and with LDL peak particle diameter and flotation rate, but not with changes in LDL-cholesterol concentration. Changes in total saturated fatty acids as well as myristic and palmitic acids were also inversely associated with changes in HL activity (P < 0.05). With the high-fat diet only, variation in dietary total saturated fatty acid intake was inversely correlated (P < 0.01) with concentrations of small, dense LDL of Sf 0-5. This correlation was significant specifically for myristic acid (P < 0.001). Stearic acid (18:0), monounsaturates, and polyunsaturates showed no significant associations with lipoprotein concentrations. These data indicate that a high saturated fat intake (especially 14:0 and 16:0) is associated with increased concentrations of larger, cholesterol-enriched LDL and this occurs in association with decreased HL activity.

Adult↗
PubMed1988

A novel glycosphingolipid hydrolyzing enzyme, glycosphingolipid ceramide deacylase, which cleaves the linkage between the fatty acid and sphingosine base in glycosphingolipids.

It has been demonstrated that the GM2 ganglioside cannot be cleaved by exo-beta-N-acetylhexosaminidases isolated from molds or bacterial sources. Here, a novel GM2 ganglioside-degrading enzyme was found in cells of Nocardia sp. This enzyme releases free fatty acids from the GM2 ganglioside. The chemical structure of the resultant lyso-GM2 ganglioside has been characterized by fast atom bombardment mass spectrometry, gas chromatography, and proton nuclear magnetic resonance spectroscopy. Using 14C-labeled GM2, at the fatty acid moiety, with stearic acid as the substrate, the optimum pH was determined to be 5.8. The enzyme was demonstrated to be capable of releasing fatty acids from GM3, GM2, GM1, and GD1a, and from neutral glycosphingolipids including Gb3-Cer, asialo-GM2, and asialo-GM1, but not from sphingolipids including Cer, Gal-Cer, Glc-Cer, and Lac-Cer. This enzyme, tentatively called glycosphingolipid ceramide deacylase, was found to be a tightly membrane-bound enzyme.

Amidohydrolases↗