Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Laurates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources
PubMed1962

Lipid metabolism of rumen ciliates and bacteria. I. Uptake of fatty acids by Isotricha prostoma and Entodinium simplex.

Washed suspensions of the ruminal ciliates, Isotricha prostoma and Entodinium simplex, concentrated C(14)-labeled oleic, palmitic, stearic, and linoleic acids within the cells during short incubation periods. Radioautographs demonstrated that oleic acid-1-C(14) was hydrogenated to stearic acid by I. prostoma, and Warburg manometric data showed that the sodium salts of oleic, valeric, caproic, and acetic acids, and methyl myristate, methyl laurate, and the triglyceride tributyrin stimulated fermentation of I. prostoma. The total lipid and free fatty acid contents of I. prostoma were determined.

Animals↗
PubMed1971

Tetracycline inhibition of a lipase from Corynebacterium acnes.

A lipase which hydrolyzes triglycerides (tricaprylin and trilaurin) and naphthyl laurate was obtained from the broth of Corynebacterium acnes cultures by ammonium sulfate fractionation. Ca(2+) and sodium taurocholate stimulated activity of the enzyme. Ethylenediaminetetraacetic acid (EDTA) did not inhibit activity of the Ca(2+)-activated enzyme, but lipolytic activity was inhibited by EDTA in the absence of Ca(2+). Tetracycline (10(-4)m) produced a slight inhibition of the lipase activity with 5 x 10(-5)m or less showing no effect on the lipase activity. However, complete inhibition by tetracycline at 10(-4)m was observed for Ca(2+)-activated enzyme. Tetracycline inhibition of the C. acnes lipase could be demonstrated at concentrations as low as 10(-6)m.

Acne Vulgaris↗
PubMed2004

Multiple triclosan targets in Trypanosoma brucei.

Trypanosoma brucei genes encoding putative fatty acid synthesis enzymes are homologous to those encoding type II enzymes found in bacteria and organelles such as chloroplasts and mitochondria. It was therefore not surprising that triclosan, an inhibitor of type II enoyl-acyl carrier protein (enoyl-ACP) reductase, killed both procyclic forms and bloodstream forms of T. brucei in culture with 50% effective concentrations (EC(50)s) of 10 and 13 microM, respectively. Triclosan also inhibited cell-free fatty acid synthesis, though much higher concentrations were required (EC(50)s of 100 to 200 microM). Unexpectedly, 100 microM triclosan did not affect the elongation of [(3)H]laurate (C(12:0)) to myristate (C(14:0)) in cultured bloodstream form parasites, suggesting that triclosan killing of trypanosomes may not be through specific inhibition of enoyl-ACP reductase but through some other mechanism. Interestingly, 100 microM triclosan did reduce the level of incorporation of [(3)H]myristate into glycosyl phosphatidylinositol species (GPIs). Furthermore, we found that triclosan inhibited fatty acid remodeling in a cell-free assay in the same concentration range required for killing T. brucei in culture. In addition, we found that a similar concentration of triclosan also inhibited the myristate exchange pathway, which resides in a distinct subcellular compartment. However, GPI myristoylation and myristate exchange are specific to the bloodstream form parasite, yet triclosan kills both the bloodstream and procyclic forms. Therefore, triclosan killing may be due to a nonspecific perturbation of subcellular membrane structure leading to dysfunction in sensitive membrane-resident biochemical pathways.

Animals↗
PubMed1999

Deacylation of purified lipopolysaccharides by cellular and extracellular components of a sterile rabbit peritoneal inflammatory exudate.

The extent to which the mammalian host is capable of enzymatic degradation and detoxification of bacterial lipopolysaccharides (LPS) is still unknown. Partial deacylation of LPS by the enzyme acyloxyacyl hydrolase (AOAH) provides such a mechanism, but its participation in the disposal of LPS under physiological conditions has not been established. In this study, deacylation of isolated radiolabeled LPS by both cellular and extracellular components of a sterile inflammatory peritoneal exudate elicited in rabbits was examined ex vivo. AOAH-like activity, tested under artificial conditions (pH 5.4, 0.1% Triton X-100), was evident in all components of the exudate (mononuclear cells [MNC] > polymorphonuclear leukocytes [PMN] > inflammatory [ascitic] fluid [AF]). Under more physiological conditions, in a defined medium containing purified LPS-binding protein, the LPS-deacylating activity of MNC greatly exceeded that of PMN. In AF, MNC (but not PMN) also produced rapid and extensive CD14-dependent LPS deacylation. Under these conditions, almost all MNC-associated LPS underwent deacylation within 1 h, a rate greatly exceeding that previously found in any cell type. The remaining extracellular LPS was more slowly subject to CD14-independent deacylation in AF. Quantitative analysis showed a comparable release of laurate and myristate but no release of 3-hydroxymyristate, consistent with an AOAH-like activity. These findings suggest a major role for CD14(+) MNC and a secondary role for AF in the deacylation of cell-free LPS at extravascular inflammatory sites.

Acylation↗
PubMed2006

Two genes encoding new carotenoid-modifying enzymes in the green sulfur bacterium Chlorobium tepidum.

The green sulfur bacterium Chlorobium tepidum produces chlorobactene as its primary carotenoid. Small amounts of chlorobactene are hydroxylated by the enzyme CrtC and then glucosylated and acylated to produce chlorobactene glucoside laurate. The genes encoding the enzymes responsible for these modifications of chlorobactene, CT1987, and CT0967, have been identified by comparative genomics, and these genes were insertionally inactivated in C. tepidum to verify their predicted function. The gene encoding chlorobactene glucosyltransferase (CT1987) has been named cruC, and the gene encoding chlorobactene lauroyltransferase (CT0967) has been named cruD. Homologs of these genes are found in the genomes of all sequenced green sulfur bacteria and filamentous anoxygenic phototrophs as well as in the genomes of several nonphotosynthetic bacteria that produce similarly modified carotenoids. The other bacteria in which these genes are found are not closely related to green sulfur bacteria or to one another. This suggests that the ability to synthesize modified carotenoids has been a frequently transferred trait.

Acyltransferases↗
PubMed1971

Sterol requirements of T-strain mycoplasmas.

T-strain mycoplasmas are very sensitive to digitonin, amphotericin B, and progesterone. This sensitivity and the relatively high content of cholesterol found in the cells indicated a possible requirement of T-strain mycoplasmas for sterols. This suspected requirement was demonstrated directly in a lipid-poor medium and can be met by cholesterol, as well as by beta-sitosterol and to a lesser degree by 7-dehydrocholesterol, cholestanol, stigmasterol, and ergosterol but not by cholesterol laurate or cholestan-3-one. Coprostanol, epicoprostanol, and epicholestanol inhibited cell growth. This inhibition could be partially reversed by increasing the cholesterol concentration in the growth medium. Because of their sterol requirement and their unique requirement for urea, T-strain mycoplasmas might be classified as the third genus in the order Mycoplasmatales.

Ammonia↗
PubMed1994

Alteration of the specificity and regulation of fatty acid synthesis of Escherichia coli by expression of a plant medium-chain acyl-acyl carrier protein thioesterase.

The expression of a plant (Umbellularia californica) medium-chain acyl-acyl carrier protein (ACP) thioesterase (BTE) cDNA in Escherichia coli results in a very high level of extractable medium-chain-specific hydrolytic activity but causes only a minor accumulation of medium-chain fatty acids. BTE's full impact on the bacterial fatty acid synthase is apparent only after expression in a strain deficient in fatty acid degradation, in which BTE increases the total fatty acid output of the bacterial cultures fourfold. Laurate (12:0), normally a minor fatty acid component of E. coli, becomes predominant, is secreted into the medium, and can accumulate to a level comparable to the total dry weight of the bacteria. Also, large quantities of 12:1, 14:0, and 14:1 are made. At the end of exponential growth, the pathway of saturated fatty acids is almost 100% diverted by BTE to the production of free medium-chain fatty acids, starving the cells for saturated acyl-ACP substrates for lipid biosynthesis. This results in drastic changes in membrane lipid composition from predominantly 16:0 to 18:1. The continued hydrolysis of medium-chain ACPs by the BTE causes the bacterial fatty acid synthase to produce fatty acids even when membrane production has ceased in stationary phase, which shows that the fatty acid synthesis rate can be uncoupled from phospholipid biosynthesis and suggests that acyl-ACP intermediates might normally act as feedback inhibitors for fatty acid synthase. As the fatty acid synthesis is increasingly diverted to medium chains with the onset of stationary phase, the rate of C12 production increases relative to C14 production. This observation is consistent with activity of the BTE on free acyl-ACP pools, as opposed to its interaction with fatty acid synthase-bound substrates.

Cloning, Molecular↗
PubMed2001

Pseudomonas aeruginosa exhibits directed twitching motility up phosphatidylethanolamine gradients.

Pseudomonas aeruginosa translocates over solid surfaces by a type IV pilus-dependent form of multicellular motility known as twitching. We wondered whether cells utilize endogenous factors to organize twitching, and we purified from wild-type cells a lipid that caused directed movement. Wild-type P. aeruginosa, but not a pilJ pilus-deficient mutant, showed biased movement up gradients of phosphatidylethanolamine (PE) established in agar. Activity was related to the fatty acid composition of the lipid, as two synthetic PE species, dilauroyl and dioleoyl PE, were capable of directing P. aeruginosa motility while many other species were inactive. P. aeruginosa PE did not contain either laurate or oleate, implying that the native attractant species contains different fatty acids. Uniform concentrations of PE increased cell velocity, suggesting that chemokinesis may be at least partly responsible for directed movement. We speculate that PE-directed twitching motility may be involved in biofilm formation and pathogenesis.

Chemotactic Factors↗
PubMed1967

Synthesis of saturated long chain fatty acids from sodium acetate-1-C14 by Mycoplasma.

Three strains of Mycoplasma, M. laidlawii A and B, and Mycoplasma sp. A60549, were grown in broth containing sodium acetate-1-C(14). The methyl esters of the phospholipid fatty acids of harvested radioactive cells were prepared and identified by comparison of their mobilities to known radioactive fatty acid methyl esters by use of a modified reversed-phase partition-thin layer chromatographic technique. No radioactive methyl oleate or methyl linoleate was detected. Compounds migrating as radioactive methyl myristate, stearate, palmitate, and, with less certainty, laurate and octanoate were detected. The qualitative findings for all three organisms appeared similar. M. laidlawii B synthesized a radioactive substance, presumably a saturated fatty acid detected as the methyl ester derivative, which migrated in a position intermediate to methyl myristate-1-C(14) and methyl palmitate-1-C(14). This work indicates that M. laidlawii A and B and Mycoplasma sp. A60549 are capable, in a complex medium containing fatty acids, of synthesizing saturated but not unsaturated fatty acids entirely or in part from acetate.

Acetates↗
PubMed1968

Anti-Pasteurella pestis factor. 3. Effects of fatty acids on Pasteurella pestis.

The bactericidal activity and the chemical and physical characteristics of lipid fractions of extracts from organs of normal mice and guinea pigs have been described previously. The present study describes the effects of commercially prepared fatty acids which are representative of those found in the extracts. Saturated fatty acids with 12, 14, and 16 carbon atoms and unsaturated fatty acids with more than one double bond were the most effective in killing Pasteurella pestis. Tweens 20 and 80, Spans 40 and 80, and some of the methyl esters of the fatty acids did not strongly inhibit P. pestis. It was concluded, therefore, that both the length of the carbon chain and the presence of the carboxyl group of the free fatty acids were important in their effects on P. pestis. Neither the very active lauric acid nor the relatively inactive oleic acid appeared to severely alter the morphology of P. pestis. Supernatant fluids from incubated mixtures of sodium laurate or sodium oleate and cells did not contain significantly greater concentrations of proteins or nucleic acids than did the controls. These observations do not preclude an alteration of the permeability of the cell walls.

Caproates↗
PubMed1968

Possible mechanisms of action of an anti-Pasteurella pestis factor.

Anti-Pasteurella pestis factor (APF) inhibited bacterial growth, but there was no evidence that APF from either mouse or guinea pig or selected fatty acids physically disrupted the cell wall. The fatty acids selected were representative of those found in APF. APF inhibited oxidation of beta-d-glucose but not oxidation of glucose-6-phosphate, whereas fatty acids inhibited the oxidation of glucose-6-phosphate but not oxidation of beta-d-glucose. The oxidation of 6-phosphogluconic acid was inhibited by both APF and free fatty acids. Furthermore, APF and potassium laurate inhibited 6-phosphogluconic dehydrogenase in a cell-free extract of P. pestis strain E.V. 76. No evidence of beta-d-glucose or glucose-6-phosphate dehydrogenases was found in the cell-free extract. The results suggested that APF and fatty acids may kill P. pestis by inactivating 6-phosphogluconic acid dehydrogenase. The effects of these agents on other enzyme systems were not excluded.

Alcohol Oxidoreductases↗
PubMed1981

Enzymatic profile of Legionella pneumophilia.

The enzyme activities of four strains of Legionella pneumophilia were investigated by using the API ZYM system (API System S.A., F-38390 Montalieu Vercieu, France) and synthetic substrates. Aminopeptidases were detected specifically against L-alanine, L-arginine, L-aspartic acid, L-cystine, L-glutaminic acid, glycine, L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-tryptophan, L-tyrosine, and L-valine. Furthermore, the bacteria possesses esterase activity splitting propionate, butyrate, caproate, caprylate, and caprate, but not laurate, myristate, palmitate, and stearate, esters. The enzymes studies were inhibited partially by aprotinin. No inhibition of phosphatase (pH range, 5.4 to 8.5) or of phosphoamidase was observed. Activities of arylsulfatase, chymotrypsin, trypsin, and glycosidases could not be detected.

Aminopeptidases↗
PubMed1991

Determination of Candida tropicalis acyl coenzyme A oxidase isozyme function by sequential gene disruption.

A recently developed transformation system has been used to facilitate the sequential disruption of the Candida tropicalis chromosomal POX4 and POX5 genes, encoding distinct isozymes of the acyl coenzyme A (acyl-CoA) oxidase which catalyzes the first reaction in the beta-oxidation pathway. The URA3-based transformation system was repeatedly regenerated by restoring the uracil requirement to transformed strains, either through selection for spontaneous mutations or by directed deletion within the URA 3 coding sequence, to permit sequential gene disruptions within a single strain of C. tropicalis. These gene disruptions revealed the diploid nature of this alkane- and fatty acid-utilizing yeast by showing that it contains two copies of each gene. A comparison of mutants in which both POX4 or both POX5 genes were disrupted revealed that the two isozymes were differentially regulated and displayed unique substrate profiles and kinetic properties. POX4 was constitutively expressed during growth on glucose and was strongly induced by either dodecane or methyl laurate and to a greater extent than POX5, which was induced primarily by dodecane. The POX4-encoded isozyme demonstrated a broad substrate spectrum in comparison with the narrow-spectrum, long-chain oxidase encoded by POX5. The absence of detectable acyl-CoA oxidase activity in the strain in which all POX4 and POX5 genes had been disrupted confirmed that all functional acyl-CoA oxidase genes had been inactivated. This strain cannot utilize alkanes or fatty acids for growth, indicating that the beta-oxidation pathway has been functionally blocked.

Acyl-CoA Oxidase↗
PubMed2001

Identification of a peroxisomal ATP carrier required for medium-chain fatty acid beta-oxidation and normal peroxisome proliferation in Saccharomyces cerevisiae.

We have characterized the role of YPR128cp, the orthologue of human PMP34, in fatty acid metabolism and peroxisomal proliferation in Saccharomyces cerevisiae. YPR128cp belongs to the mitochondrial carrier family (MCF) of solute transporters and is localized in the peroxisomal membrane. Disruption of the YPR128c gene results in impaired growth of the yeast with the medium-chain fatty acid (MCFA) laurate as a single carbon source, whereas normal growth was observed with the long-chain fatty acid (LCFA) oleate. MCFA but not LCFA beta-oxidation activity was markedly reduced in intact ypr128cDelta mutant cells compared to intact wild-type cells, but comparable activities were found in the corresponding lysates. These results imply that a transport step specific for MCFA beta-oxidation is impaired in ypr128cDelta cells. Since MCFA beta-oxidation in peroxisomes requires both ATP and CoASH for activation of the MCFAs into their corresponding coenzyme A esters, we studied whether YPR128cp is an ATP carrier. For this purpose we have used firefly luciferase targeted to peroxisomes to measure ATP consumption inside peroxisomes. We show that peroxisomal luciferase activity was strongly reduced in intact ypr128cDelta mutant cells compared to wild-type cells but comparable in lysates of both cell strains. We conclude that YPR128cp most likely mediates the transport of ATP across the peroxisomal membrane.

Adenosine Triphosphate↗
PubMed1975

Lipase and esterase formation by psychrophilic and mesophilic Acinetobacter species.

Acinetobacter O16, a psychrophilic species, produced extracellular lipase (measured by hydrolysis of olive oil, tributyrin, or beta-naphthyl laurate) when grown on a complex medium (peptone plus yeast extract). Most lipase was produced during the logarithmic phase of growth. Very little cell-bound lipase was formed. These cells also produced an esterase (measured by the hydrolysis of beta-naphthyl acetate). At first, all esterase was cell bound; significant amounts appeared in the external medium late in growth. Breaking the cells did not increase cell-bound lipase activity. After breaking of the cells, most of the cell-bound lipase and esterase activity was solubilized, even after very high speed centrifugation. No appreciable amounts of these enzymes were released by osmotic shock. Lipase formation was greatly affected by nutrient conditions. Lowering either the yeast extract of the peptone content of the normal complex medium lowered or abolished lipase formation. Esterase activity was lowered to a lesser extent. Cells growing in synthetic amino acid plus vitamin medium or in acid-hydrolyzed casein produced substantial amounts of esterase but no cell-free or cell-bound lipase. However, if sodium taurocholate was added to these media, lipase was produced. Greatest production occurred if a mixture of di- and poly-peptides was also present. Taurocholate also stimulated lipase production in the normal complex medium. Adding Tween 80 or ethanol to the normal complex medium inhibited lipase production. Sodium acetate, oleic acid, olive oil, or Tween 20 added to synthetic media did not affect lipase production. The psychrophile grew more quickly at 30 degrees C than at 15 or 20 degrees C but produced more lipase at the lower temperatures. Esterase production was about the same at 20 and 30 degrees C. A mesophilic Acinetobacter species produced the same amount of lipase and esterase at 20 and 30 degrees C. The best production of lipase by the psychrophile occurred in standing cultures.

Acinetobacter↗
PubMed1991

Retinol storage in the rat liver after daily intramuscular administration of physiological doses of a vitamin A oil emulsion.

We have recently shown the kinetic behavior of liver retinyl esters in rats with adequate vitamin A levels receiving oral vitamin supplementation. In the present work we have studied the effects of intramuscular administration of a vitamin A preparation on the metabolism of vitamin A in the rat. Retinol administered intramuscularly to rats in the form of an emulsion brought about a significant increase in the serum and liver concentration of vitamin A; this increase was slightly less than in orally treated rats. In each group, retinyl palmitate constituted 80-85% of the total retinyl esters, followed by stearate (9-13%), laurate, palmitoleate, myristate, linoleate and pentadecanoate making up 3-10%. The subcellular localization of all retinyl esters is similar and dependent on age but not on the route of administration. These results indicate that although the best hepatic storage is achieved with an orally administered vitamin A emulsion, the intramuscular administration of a physiological dose might provide an effective supplementation method if oral vitamin A is contraindicated.

Administration, Oral↗
PubMed1975

Effect of fatty acids on the stimulated gastric secretion in man.

Solutions and emulsions of sodium or potassium salts in a series of saturated fatty acids from C8 to C18 were given in a dose of 0.5 g intraduodenally to healthy males or patients with healed duodenal ulcer. A double-lumen Sarles tube with a balloon placed in the proximal duodenum was used. The substances were instilled after a plateau of gastric acid secretion induced by a continuous infusion of pentagastrin was reached. In order to exclude unspecific effects, the test solutions were adjusted to a pH around 7.0 and to plasma isosmolality. Compared with the other tested substances, the emulsion of 0.5 g sodium-oleate was the most effective in inhibiting the stimulated gastric acid secretion. Sodium caprinate and caprylate had a considerable, but smaller effect than oleic acid on the secretory plateau. Palmitate and laurate provoked only a slight decrease in acid secretion. Myristate was ineffective. These results could suggest that different receptors are responsible for fat-induced inhibition of the gastric acid secretion.

Adult↗
PubMed1977

Circulating platelet aggregates and thrombocytopenia induced by intravenous infusions of arachidonic and lauric acids in guinea pigs.

Slow intravenous infusion of Na laurate (NaL) into guinea pigs caused a rapid appearance of platelet aggregates in the arterial blood and a precipitous fall in platelet counts. During the infusion of Na arachidonate (NaA) thrombocytopenia developed slowly, and few and smaller platelet aggregates appeared in the arterial blood. Considerably more guinea pigs died during or after the NaA infusion than after administration of NaL. The possibility that arachidonic acid and other long-chain fatty acids may play a role in the development of thrombosis and thromboembolism is discussed.

Animals↗