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At least 1,441 records · Page 80Linked to original sources
PubMed1970

Gel permeation chromatography of neutral hydroxy lipids on Sephadex LH-20.

Gel-permeation chromatography on Sephadex LH-20, using ethanol as eluent, permits the resolution of neutral hydroxy lipids according to molecular size. The influence of molecular shape, functional groups, chain lengths, and degree of unsaturation, as well as the effect of the eluent on the elution pattern are discussed. The usefulness of the method for the separation of classes of hydroxy lipids which cannot be resolved by other chromatographic procedures, is demonstrated. Examples include the separations of 1,2- and 1,3-diglycerides from long-chain alcohols, and of alkyl ethanediol monoethers from cholesterol.

Alcohols↗
PubMed1975

[Studies on the lipid composition in serum and lymphocytes in chronic leukemia].

In 33 patients with chronic lymphatic leukaemia (CLL) the lipids were examined quantitatively and qualitatively in the serum and in the lymphocytes. Besides the 5 main categories of lipids, lysolecithin, sphingomyelin, lecithin and cephalin as well as cholesterol ester subfractions were determined according to their degree of saturation of their fatty acids. Patients suffering from CLL were found to have a moderately raise of serum triglycerides and an increase of cholesterol esters with simple unsaturated fatty acids. Simultaneously the fraction of ester with poly-unsaturated fatty acids is lowered. Leukaemic lymphocytes reveal in general a lowered total lipid content. It mainly consists of phosphatides and free cholesterol. Moreover, the leukaemic lymphocytes contrary to normal ones reveal a lowered content of cholesterol esters, diglycerides and triglycerides.

Aged↗
PubMed1970

Enzymatic synthesis and decarboxylation of phosphatidylserine in Tetrahymena pyriformis.

Cell-free extracts of the protozoan Tetrahymena pyriformis have been found to catalyze the following reactions: Phosphatidylethanolamine + L-Serine <==> Phosphatidylserine + Ethanolamine. Phosphatidylserine --> Phosphatidylethanolamine + CO(2) divided by Net: L-Serine --> Ethanolamine + CO(2). The biosynthesis of phosphatidylserine in this organism resembles that found in higher animals. In contrast, phosphatidylserine is formed in bacteria in a reaction between CDP-diglyceride and L-serine. A detailed description is presented of the enzyme that catalyzes the synthesis of phosphatidylserine in Tetrahymena by the exchange reaction, together with some properties of the phosphatidylserine decarboxylase in this organism.

Amino Alcohols↗
PubMed1968

Specific distribution of short-chain fatty acids in molecular distillates of bovine milk fat.

Triglycerides with a total of 34-44 acyl carbon atoms have previously been shown to account for nearly 50% of bovine milk fat. About 80% of this material was isolated by molecular distillation and a representative fraction of these glycerides was subjected to a stereospecific analysis. Of the 29 moles % of C(4)-C(8) fatty acids present in the analyzed fraction, at least 95% were specifically attached to the glycerol molecule in the position corresponding to carbon 3 of sn-glycerol 3-(dihydrogen phosphate) (L-alpha-glycerophosphate). The distribution of the other fatty acids (C(10) or greater) did not show such marked specificity for either the 1- or the 2-position. The data support the hypothesis that the short-chain fatty acids are esterified with long-chain diglycerides, or are substituted in glycerophosphatide intermediates, during the final step in the biosynthesis of milk fat triglycerides.

Animals↗
PubMed1968

Lipid biosynthesis in chloroplast mutants of barley.

The capacity of leaf slices from light-grown seedlings of wild type barley and 10 xantha mutants at six different gene loci to incorporate acetate-(14)C into various lipids has been investigated. The fatty acid composition of the leaf lipids in these lethal mutants was similar to that of the wild type, but the fatty acid labeling pattern in the individual lipid classes can be drastically altered by these mutations, which affect chloroplast differentiation. A genetic block in chlorophyll synthesis, caused by mutations in the xan-f locus, leads to a repression of the formation of chloroplast membranes and of acetate incorporation into phospho-, sulfo-, and galacto-lipids (the acetate being preferentially channeled into a lipid fraction containing steroids and free fatty acids). Two leucine "auxotrophs" at different loci, which in the absence of leucine in the growth medium produce giant grana and accumulate some chlorophyll, differed considerably in the amount of labeling of their polar lipids during incubation. Leaves of xan-a(11), containing plastids with little chlorophyll, highly disorganized membrane systems, and large bodies with osmiophilic deposits, were nonetheless equal to wild type in their capacity to incorporate acetate-(14)C into phospho-, sulfo-, and galacto-lipids. The mutants at the xan-m locus have plastids with undispersed prolamellar bodies and osmiophilic packages of grana-like membranes associations. Leaf slices of these mutants synthesized considerably more linolenic acid-(14)C, which was incorporated into monogalactosyl diglycerides, than did slices of the wild type. This led to a labeling pattern of the fatty acids in the monogalactolipids which was remarkably similar to their endogenous fatty acid composition.

Acetates↗
PubMed1979

[Lipolytic activity from milk isolated strains of the species Thermoactinomyces vulgaris, Tsiklinsky 1899 (author's transl)].

Thirty strains of the species Thermoactinomyces vulgaris (Tsiklinsky, 1988) were isolated from milk and tested for their lipolythic activity. After incubation for 120 hours at 55 degrees C they formed distinct diffusion zones on culture media containing tributyrin and tween-80. In all strains exocellular lipases were found. Their action on the milk fat increased the number of the free fatty acids. Triglycerides, free fatty acids as well as diglycerides and monoglycerides were identified as split products chromatographically. The activity of the endolipases was lower. In four of the most active endolipases cholesterol was identified as split product of milk fat in addition to those mentioned above.

Animals↗
PubMed1969

Effect of carbon tetrachloride administration on the synthesis of triglycerides and phospholipids in rat liver.

In vivo incorporation of choline-methyl-(14)C into liver lecithin and its biosynthetic precursors was studied in CCl(4)-treated rats. Radioactivity in cytidine diphosphoryl (CDP-)choline and lecithin was reduced to one-third of control levels, whereas that of phosphorylcholine was increased to 4.7 times control levels. Incorporation of phosphorylcholine-(32)P into lecithin by homogenates prepared from livers of CCl(4)-treated animals was reduced, but conversion of CDP-choline-(32)P to lecithin by the isolated microsomal fraction did not show any significant depression. A block in the synthesis of CDP-choline is indicated. The in vivo utilization of methionine for lecithin synthesis was not affected. After intravenous injection of palmitic acid-1-(14)C, radioactivity of triglycerides from microsomal and mitochondrial fractions was markedly lower than the controls, whereas radioactivity of triglycerides in the soluble fraction was greatly increased. Radioactivity of diglycerides changed from 0.5% of total lipids in the control to 10% of total lipids in CCl(4)-treated animals. Incorporation of palmitic acid into phospholipids was also suppressed. The results demonstrate that synthesis of both phospholipids and triglycerides is inhibited in rats 4-5 hr after CCl(4) administration.

Animals↗
PubMed1966

In vivo studies on pathways for the biosynthesis of lecithin in the rat.

The in vivo biosynthesis of lecithin in rats has been studied with the precursors choline-1,2-(14)C, ethanolamine-1,2-(14)C and methionine-CH(3)-(14)C or -CH(3)-(3)H. Lecithin synthesis from choline is rapid in all organs. No sex difference was observed in this pathway. The biosynthesis of lecithin by methylation of phosphatidyl ethanolamine is of quantitative significance in the liver, but not in extrahepatic tissues. More lecithin is synthesized by this pathway in female rats. In liver the lecithin synthesized via both pathways enters a common pool which is in rapid equilibrium with lecithin of blood plasma. A sex difference in the utilization of radioactive ethanolamine for the formation of phosphatidyl ethanolamine was observed (greater utilization in the female). Incorporation of ethanolamine into phospholipids of extrahepatic tissues was slow in both sexes. With labeled methionine as precursor the liver cytidine diphosphate (CDP) choline had a specific activity identical with that of liver lecithin after 20 min, while the specific activity of phosphoryl choline remained low. With labeled choline as precursor the phosphoryl choline reached a specific activity 50 times that of lecithin after 20 min, while the specific activity of CDP choline was only four times that of lecithin. These findings indicate that the reaction: CDP choline + diglyceride right harpoon over left harpoon phosphatidyl choline + CMP is freely reversible in vivo.

Amines↗
PubMed1977

Histochemical and thin layer chromatographic analyses of neutral lipids in Echinostoma revolutum metacercariae cultured in vitro.

Excysted metacercariae of Echinostoma revolutum cultured in vitro in the defined medium, NCTC 135 supplemented with 20% hens' egg yolk, doubled their mean relative body area and showed significant sucker growth within 14 days. Histochemical Oil Red O staining showed neutral fat mainly in the excretory system of excysted metacercariae and in adults grown in the domestic chick. In vitro cultured worms showed neutral fat in the intestine, parenchyma, and excretory system. As detected by TLC the major neutral lipid fractions were free fatty acids for excysted metacercariae; free sterols for adults grown in chicks; and triglycerides, free fatty acids, and free sterols for cultured worms. Excysted metacercariae excreted free fatty acids into a nonnutrient incubation medium, whereas cultured worms excreted diglycerides, triglycerides, and free fatty acids into the medium.

Animals↗
PubMed1966

Lipid composition of rat mammary carcinomas, mammary glands, and related tissues: endocrine influences.

The lipids of mammary glands and mammary carcinomas from rats in various hormonal states were studied and compared with each other, with adipose tissue, and with a new transplantable sarcoma derived from cultured mammary carcinoma cells. When large doses of estradiol-17 Beta were administered to the host, cells of a few carcinomas became engorged with triglyceride containing an increased proportion of C(10)-C(14) fatty acids-a characteristic of milk fat. Cancers capable of fatty transformation must retain in latent form the enzyme system for fatty acid synthesis possessed by mammary epithelium; estradiol-17 Beta apparently activates this system. The lipid composition of retroperitoneal adipose tissue resembled that of the mammary tissue of virgin rats; this indicates similarity between retroperitoneal fat and the adipose component of mammary gland. Relative to the dry nonfat material present, the phospholipid content of adipose tissue was greater than that of the other tissues. Generally, differences in lipid composition between tissues were in amounts of triglyceride present and proportions of fatty acids in the triglyceride fraction. The ratios of cholesterol and cholesterol ester to phospholipid were similar in normal and neoplastic tissues. The amounts of free fatty acid, monoglyceride, and diglyceride were roughly proportional to the amount of triglyceride present.

Adipose Tissue↗
PubMed1966

Partial purification of monoglyceride lipase from adipose tissue.

A monoglyceride lipase was partly purified from extracts of rat adipose tissue by ammonium sulfate fractionation, alcohol precipitation, and lyophilization, or by ammonium sulfate fractionation, sodium deoxycholate treatment, and a second ammonium sulfate fractionation. Partial purification and heat denaturation showed the lipase to be different from tributyrinase and from an enzyme(s) which hydrolyzes diglycerides and triglycerides. Although the best preparations hydrolyzed monobutyrin this activity decreased with purification, indicating that the enzyme acts on insoluble substrates and is therefore a lipase and not an esterase. Further-more, classification of the enzyme as a lipase is consistent also with its behavior with inhibitors, since low concentrations of esterase inhibitors, e.g., fluoride, sodium deoxycholate, and physostigmine did not inhibit lipolytic activity. Inhibition studies with EDTA, sodium pyrophosphate, protamine, and fluoride showed that the enzyme differs from clearing factor lipase. The enzyme catalyzed hydrolysis of monostearin in the pH range 6.3-9.0, with a maximum at 7.4-7.6.

Adipose Tissue↗
PubMed1966

Low temperature partial alcoholysis of triglycerides.

Egg triglycerides chromatographed on silicic acid are eluted in a skew curve in which fatty acid composition varies. The triglycerides were cleaved by sodium methoxide in chloroform-methanol at 0 degrees C to yield diglycerides (11.3%) and monoglycerides (17.5% of original triglycerides) after 3 min. Complete cleavage to fatty acid methyl esters and glycerol was obtained at 18 min at 0 degrees C or 5 min at room temperature.

Chromatography↗
PubMed1967

Stereospecific analysis of triglycerides: an alternative method.

A new method for the stereospecific analysis of triglycerides is demonstrated on a corn oil which had been analyzed by an earlier method. The triglyceride (1,2,3-triacyl L-glycerol) was partially degraded by means of methyl magnesium bromide. The 1,3-diglyceride was then isolated, and converted into l-2-phosphatidyl phenol, from which phospholipase A cleaved the fatty acids from position 1. The remaining lysophosphatide was analyzed to yield the fatty acids at position 3 of the original triglyceride. The fatty acid composition of position 2 was determined after hydrolysis of the corn oil with pancreatic lipase. This method has the advantage over the one reported previously of yielding direct analyses of the fatty acids in each of the three positions.

Chromatography, Thin Layer↗
PubMed1980

Inhibition of cyclic AMP accumulation in hamster adipocytes with phosphatidic acid: differences and similarities with alpha adrenergic effects.

Clark et al (Journal of Cyclic Nucleotide Research 6:37 (1980)) demonstrated phosphatidic acid inhibition of cyclic AMP formation in WI-38 fibroblasts and suggested the hypothesis that cholinergic inhibition of adenylate cyclase is mediated through accumulation of this phospholipid. In view of these data, we tested the hypothesis that phosphatidic acid is involved in alpha-adrenergic inhibition of cyclic AMP formation in hamster adipocytes. The effects of phosphatidic acid on hormone and methyl xanthine stimulated cyclic AMP accumulation and lipolysis were studied. Phosphatidic acid inhibited 3-isobutyl-1-methyl xanthine (IBMX) stimulated cyclic AMP formation. The maximum inhibition (85% to 100%) of IBMX stimulated cyclic AMP accumulation was detected at 1.0 microM phosphatidic acid. When lipolysis was measured, however, inhibitory effects of phosphatidic acid were not evident until the concentration of phospholipid was increased to 300 microM. The cyclic AMP lowering and antilipolytic effects were detected using egg yolk phosphatidic acid, dipalmitoyl phosphatidic acid, dimyristoyl phosphatidic acid, distearoyl phosphatidic acid and palmitoyl lysophosphatidic acid but not with phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine or 1,2- diglyceride. In contrast to phosphatidic acid, clonidine or N6-phenylisopropyl adenosine inhibited lipolysis in concert with inhibition of methyl xanthine stimulated cyclic AMP accumulation. Cyclic AMP accumulation increased by isoproterenol in combination with IBMX was partially blocked by clonidine but not by phosphatidic acid. These results show similarities as well as differences between clonidine and phosphatidic acid actions on hamster fat cells and do not, therefore, provide unequivocal support for the possibility that phosphatidic acid is intimately involved in alpha-adrenergic effects on hamster adipocytes. However, the high selectivity of phosphatidic acid suggests a physiological role of this agent in regulation of adenylate cyclase.

1-Methyl-3-isobutylxanthine↗
PubMed1984

The activation of protein kinase C by biologically active lipid moieties of lipopolysaccharide.

The monosaccharide lipid A precursor, N2,O3-diacylglucosamine 1-phosphate (Escherichia coli lipid X), has been shown previously to be a potent B-lymphocyte mitogen. We now report that lipid X interacts with macrophages, stimulating turnover of phosphatidylinositol, deacylation of phospholipids, and release of arachidonic acid. In addition, the monosaccharide lipid X, the incomplete lipid A disaccharides found in KDO-deficient mutants, and crude free lipid A by itself activate protein kinase C isolated from RAW 264.7 macrophages. This activation is augmented by diglyceride, a product of phosphatidylinositol turnover. Like the lipid X-induced mitogenesis of B-lymphocytes, lipid X activation of macrophages and the cell-free activation of protein kinase by lipid X require the presence of the O-linked hydroxymyristoyl residue at position 3. We suggest, therefore, that some of the biological effects of lipid A may be mediated by its interaction with protein kinase C.

Animals↗
PubMed1983

The biosynthesis of membrane-derived oligosaccharides. A membrane-bound phosphoglycerol transferase.

Membrane-derived oligosaccharides, found in the Escherichia coli periplasmic space (Schulman, H., and Kennedy, E. P. (1979) J. Bacteriol. 137, 686-688), are composed of 8-10 units of glucose, the sole sugar, in beta 1 leads to 2 and beta 1 leads to 6 linkages (Schneider, J. E., Reinhold, V., Rumley, M. K., and Kennedy, E. P. (1979) J. Biol. Chem. 254, 10135-10138). Oligosaccharides in this family are variously substituted with succinyl ester residues, as well as with sn-1-phosphoglycerol and phosphoethanolamine, both derived from membrane phospholipids. These negatively charged oligosaccharides may function in cellular osmoregulation since their synthesis is under osmotic control (Kennedy, E. P. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 1092-1095). We now report initial characterization of an enzyme catalyzing transfer of phosphoglycerol residues from phosphatidylglycerol to membrane-derived oligosaccharides or to synthetic beta-glucoside acceptors. The products are sn-1,2-diglyceride and beta-glucoside-6-phosphoglycerol. Localized in the inner membrane, the transferase has a requirement for divalent cations, of which manganese is most effective, and a pH optimum of 8.9 in vitro.

Cations, Divalent↗
PubMed1984

The product of the F sex factor traT surface exclusion gene is a lipoprotein.

The product of the Escherichia coli sex factor F traT gene (TraTp), an outer membrane protein of Mr = 25,000, is covalently modified in vivo by the addition of glycerol and fatty acids. Consistent with this result, and as would be expected for a bacterial lipoprotein, the novel amino acid glycerylcysteine can be detected in purified TraTp. Being a secreted protein, TraTp is made from a signal sequence containing precursor, and glycerol and fatty acids can be detected in both the precursor and mature (processed) species of TraTp. The peptide antibiotic globomycin inhibits the cleavage of the pro-TraTp signal sequence, but not the glycerol and fatty acid modification. Diglyceride modification of the Cys residue at the site of signal sequence cleavage probably precedes and is a prerequisite for processing of the TraTp signal sequence. Thus, TraTp appears to be a typical E. coli lipoprotein, having a pathway for modification and processing that is similar to that of Braun's lipoprotein (the major outer membrane lipoprotein).

Amino Acid Sequence↗