Galactosyl Diglycerides Research Articles

Analysis of lipid composition of cell-bound membrane vesicles (CBMVs) derived from endothelial cells

Cell-bound membrane vesicles (CBMVs), a novel type of membrane vesicles, have been identified through a series of characterization tools. However, the lipid composition of CBMVs has not yet been characterized. This study focuses on the differences in lipid composition between CBMVs and cell membranes. In order to determine the lipid composition of CBMVs and cell membranes of Human umbilical vein endothelial cells (HUVECs) and find out differential metabolites, this study was carried out by isolating CBMVs lipids and characterizing them using high-performance liquid chromatography tandem secondary mass spectrometry (LC-MS/MS). The results showed the presence of 213 up-regulated and 726 down-regulated lipids in CBMVs compared to cell membranes which produced CBMVs. There are lipids expressed in CBMVs and not in cell membranes: DGDG 18:0_8:0, DGDG O-8:0_16:1, DGDG O-26:7_26:7, DGDG O-16:3_26:7, TG 15:4_21:5_22:5; 4O, PC 49:11, PG 19:5_38:10, PI 60:14, PI 44:9, PI 25:2, PI 43:5, PI 50:10, PS 55:10. DGDG (digalactosyl diglyceride), MGDG (monogalactosyl diglyceride) belongs to galactosyl diglyceride, promotes fat catabolism, which also has antioxidant and anti-inflammatory effects, and unsaturated diacylglycerols are a class of antioxidant compounds, which enables CBMVs to have a therapeutic potential.

Formation of phosphatidic acid, ceramide, and diglyceride on radiolysis of lipids: identification by MALDI-TOF mass spectrometry

By use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, phosphatidic acid was found to be the main product of γ radiolysis of cardiolipin, phosphatidylinositol, and phosphatidylglycerol. It has been shown that γ irradiation of such glycolipids as cerebroside and galactosyl diglyceride leads to formation of ceramide and diglyceride, respectively. These findings, combined with those obtained earlier, allowed an assumption to be made that, owing to radiation-induced free radical fragmentation of lipids in their polar moiety, formation of signaling molecules can occur.

Oligodendrocyte cell surface recognized by a novel monoclonal antibody specific to sulfatide

A rat monoclonal antibody (OL-1) was obtained by in-vitro immunization of rat spleenocytes with paraformaldehyde-fixed primary cultured glial cells derived from newborn rat brain and subsequent fusion with a rat myeloma cell line. The antibody secreted by the hybridoma immunostains live rat and mouse oligodendrocytes in primary and secondary cultures. The antibody binds specifically to oligodendrocytes and myelin structures in-situ. Radioimmunolabelling assays with a number of purified glycolipids offer thin layer chromatography separation show that OL-1 antibody binds strongly to sulfatide and to a lesser extent to galactosyl diglyceride.

Relationship between dietary lipids, midgut lipids, and lipid absorption in eight species of Lepidoptera reared on artificial and natural diets

Lipids present in the diet, midgut lumen, and midgut tissue were analyzed by thin-layer chromatography in larvae of eight species of Lepidoptera representing three families. Pieris brassicae reared on Brassica oleracea, Heliothis zea, reared on Zea mays, and Anticarsia gemmatilis, reared on Glycine max, were found to digest leaf galactosyl diglycerides, phosphatidylcholines, and phosphatidylglycerols. Triacylglycerols were present as minor lipids in these diets. During digestion of leaf lipids, several polar lipids accumulated in the midgut lumen of P. brassicae, but only trace amounts were observed in the midgut lumen of the other species examined. Midgut tissue lipids of all species were relatively similar, but species differences were observed in the synthesis of some lipids in midgut tissue. Although little esterification of sterols occurred in the midgut tissue of P. brassicae, sterol esters were prominent in the midgut of H. zea, H. subflexa and Diatraea grandiosella. Among the midgut tissue lipids of P. brassicae, triacylglycerols were found to have the most rapid turnover rate, suggesting that triacylglycerols have a critical role in the transfer of lipid across the gut wall.

Binding of Antibodies onto the Thylakoid Membrane. VI. Asymmetric Distribution of Lipids and Proteins in the Thylakoid Membrane

The maximal binding of antibodies out of monospecific antisera to proteins and lipids onto three different chloroplast preparations is compared. In these preparations different parts of the thylakoid membrane surface are accessible to antibodies. Whereas stroma-freed chloroplasts bind antibodies only at the outer surface, also the inner membrane surface is exposed in the two chloroplast preparations which were obtained by ultrasonication and subsequent fractionating centrifugation. In the ultrasonic sediment the inner surface is prevailing. In the ultrasonic supernatant antibodies do not only react with the inner and outer surface but also with con­siderable parties of the interior of the thylakoid membrane. It was found that the thylakoid membrane surface exposed to the stroma consists preponder­antly of proteins whereas the surface directed towards the interior of the thylakoids consists mainly of lipids. All proteins involved in electron transport such as ferredoxin, ferredoxin- NADP+-reductase, plastocyanin, cytochrome f and the coupling factor of photophosphorylation are detectable in the outer surface. The molecules of the coupling factor span the thylakoid membrane from the outside to the inside. They hinder the binding of antibodies to mono- galactosyl diglyceride and to a polypeptide with the apparent molecular weight 24000. The polypeptide 24000 is a major component of the membrane proteins, and is detected on the outer and inner surface of the membrane. The major part of this polypeptide, however, is located in the interior of the thylakoid membrane. The lipid mixture has a different composition in the outer surface than on the inside face of the membrane. The sulfoquinovosyl diglyceride and the phosphatides, phosphatidyl glycerol, phosphatidyl cholin and phosphatidyl inositol are stronger concentrated in the outer surface than in the inside face. The neutral monogalactosyl diglyceride and di- or trigalactosyl diglyceride, however, occur in the inner surface in higher concentrations than in the outer surface. The major part of the sulfoquinovosyl diglyceride and of the monogalactosyl diglyceride are located in the interior of the membrane.

Levels of cerebrosides, sulfatides, and galactosyl diglycerides in different regions of rat brain change during maturation and distribution in subcellular fractions of gray and white matter of sheep brain

The concentrations of galactosyl non-hydroxyceramide, galactosyl hydroxyceramide, non-hydroxysulfatide, hydroxysulfatide, monogalactosyl diglyceride, and glucosyl ceramide were determined in brain stem, cerebellum, cerebral hemisphere, and diencephalone of brains from 5-, 10-, 14-, 19-, 26- and 37-dayold rats by high performance liquid chromatography. The concentrations of cerebrosides and sulfatides increased rapidly in all areas of the brain during the maturational period. The most rapid increase was in the brain stem, and the least rapid increase was in the cerebral hemisphere. Galactosyl diglyceride increased somewhat more slowly than that of sphingolipids and leveled off in all parts of the brain after 26 days. Glucosyl ceramide was detected in all areas of 5- and 10-day-old brain and in the cerebral hemisphere and diencephalone of 14-day-old brain. All subcellular fractions of sheep brain white matter contained similar sphingolipid compositions. However, 94% hydroxy- and non-hydroxycerebrosides and 95% hydroxy- and non-hydroxysulfatides were found in two fractions rich in myelin. The gray matter subcellular fractions containined approx. 6% of the sphingolipids found in white matter. The fractions from gray matter containing myelin and nuclei had a similar sphingolipid composition as white matter. In the other fractions from gray matter the lipid concentrations were much lower and the composition was entirely different. In general, these fractions had relatively higher hydroxycerebroside and sulfatide concentrations.

Mesocarp, seed and pollen lipids of Raphia palms

AbstractThe lipid classes, fatty acids and sterols of the mesocarp, seed and pollen lipids of five species of Raphia palms endemic to Nigeria were analysed. Apart from quantitative differences in the fatty acid compositions, chromatographic analyses demonstrated very little change in the patterns of the characteristic lipids associated with either the mesocarps, seed endosperms or pollens. Mesocarp lipids contained mainly triglycerides, while palmitic, oleic and linoleic acids were the major acids. Contrary to published data for seed lipids, Raphia seed endosperms contained a relatively small amount of triglycerides and a high proportion of polar lipids. Fatty acids associated with this tissue were not only highly unsaturated, but were significantly different from typical fatty acids of seed lipids. Raphia pollens, on the other hand, showed a complex array of lipid types. Triglycerides, sterols and sterol esters constituted the main neutral lipids while phosphatidyl choline, phosphatidyl inositol, phosphatidyl ethanolamine and galactosyl diglycerides represented the polar fraction. Apart from minor trends, palmitic, oleic and linoleic acids constituted the major fatty acids in all species. The biological importance of the steroidal sapogenins found in all organs is discussed.

The polar lipids of Actinomyces Viscosus

The polar lipids of Actinomyces viscosus were identified as galactosyl diglyceride, phosphatidyl choline, cardiolipin, phosphatidyl glycerol and phosphatidyl inositol dimannosides.

Lipids of the yeast Hansenula anomala

An analysis of the free lipids of Hansenula anomala was performed. The main fatty acids obtained by saponification of whole cell crude lipids were palmitic, C18:1, C18:2 and C18:3 acids. In mitochondrial lipids the tri-unsaturated acid was present as traces. Fatty acid composition of each class of lipids was also determined. Phosphatidylcholine and phosphatidylethanolamine were the main phospholipids; phosphatidylserine, phosphatidylinositol and cardiolipin were also characterized. The most abundant sterols were ergosterol and lanosterol. An acetate of a 24-ethyl cholesterol was also isolated. Two glycolipids, a galactosyl diglyceride and a glucosyl ceramide were identified; concerning the galactosyl diglyceride, the content of C18:3 acid was higher than in other lipid classes. In the glucosyl ceramide, the main fatty acid was alpha-hydroxy C18:0 acid; C16:0, C18:1, C18:2 and C18:3 acids were present too. The long chain base was shown to be C18-phytosphingosine (4-hydroxy C18 sphinganine). Some similarities and differences with Saccharomyces cerevisiae are discussed.

Examination and composition of some legume seeds (author's transl)

The chemical composition of some legume seeds is reviewed. It was found that soy (Glycine soja), field beans (Vicia faba), Vicia sativa and Lens culingris (red seeds) have the highest protein content. There were only minor differences in amino acid composition except for glutamic acid. The lysine content of legume seeds was high. Lysine is the most limiting essential amino acid in cereal proteins, therefore cereal products can be improved nutritionally by addition of legume seed flour. Examination of polar lipids by thin layer chromatography revealed that lecithin, phosphatidyl ethanolamine and phosphatidyl inositol were the major components. However, Lupinus angustifolius contained two unknown polar lipid classes.--In contrary to previous literature the ripe legume seeds contained only a very small amount of galactosyl diglycerides; however legume seeds contain higher amounts of the compounds. The conection between biosynthesis of linolenic acid and the presence of galactosyl diglycerides in higher plants is discussed.

Light-independent stoichometry of galactosyl diglyceride and chlorophyll accretion during light-induced chloroplast membrane synthesis in [formula omitted

In photobiotic Euglena gracilis , chlorophyll biosynthesis takes place at a rate which is a direct function of light intensity. There is stoichiometry between chlorophyll accumulation and that of galactosyl diglycerides. This stoichiometry remains relatively invariant, regardless of the wide changes in chlorophyll content brought about in response to controlled variation of light intensity. These findings suggest that the formation of chlorophyll-containing photoreceptor membranes may be paced and stabilized by concurrent synthesis of galactosyl diglycerides.

Metabolic relationships between myelin subfractions: entry of galactolipids and phospholipids.

Abstract— Partially purified myelin from the brains of 17‐day‐old rats was separated into 4 subfractions on a three‐step sucrose gradient by virtue of heterogeneity in density and particle size. Precursor‐product relationships between different membrane fractions were investigated by determining the specific radioactivity of individual lipids in each subcellular fraction 15 min after intracranial injection of an appropriate precursor. Rats were injected with [2‐3H]glycerol. myelin subfractions prepared, and individual lipids separated by TLC. For choline and ethanolamine phospholipids, specific radioactivity was highest in the densest fraction (D), intermediate in the next densest fraction (C), and lowest in the lighter fractions (B and A). Similar results were observed for cerebroside and sulphatide when [3H]galactose was the precursor. These data are consistent with (but do not prove) a precursor‐product relationship for individual lipids from the densest to the lightest subfraction.Another experimental design involving time staggered injections of [3H] and [14C] precursors was developed which enables a more definitive result with regard to precursor‐product relationships to be obtained. A precursor‐product relationship between a given lipid in a dense myelin membrane fraction, and the same lipid in a lighter subfraction, would be indicated by a change in isotope ratio. If there is no precursor‐product relationship. Ihe isotope ratio should be constant. Such experiments were done with [3H] and [14C]glycerol. The data indicated that phosphatidyl ethanolamine and its plasmalogen analog were added first to the densest subfraction and then in turn to the lighter subfractions. In contrast, phosphatidyl choline and its plasmalogen analog were added “simultaneously” (i.e. with delays of much less than 15min) to each of the subfractions. Similar experiments with [3H] and [14C]galactose showed that cerebroside, sulphatide and galactosyl diglyceride also entered the subfractions simultaneously rather than in sequential order. Thus the assembly of the myelin sheath involves an obligate order of addition of certain lipids. while other lipids are probably added in a random order.

Lipids of Fontinalis antipyretica

Fatty acid compositions of the lipids of Fontinalis antipyretica shows the presence of octadeca-9, 12-dien-6-ynoic, octadeca-9,12,15-trien- 6-ynoic and eicosa-11,14-dien-8-ynoic acids as the major components of the triglycerides. These acetylenic acids were not present in the galactosyl diglycerides. The moss lipids also contained relatively large amounts of two novel acetylenic methyl ketones with an unsaturation pattern analogous to that of the C 18 acetylenic acids.

The sugar components of the galactosyl diglycerides from green plants

Preparative TLC was used to separate the MGDG and DGDG fractions from 22 green plant species. Methanolysis of the separated fractions gave methyl glycosides which were analysed by GLC as trimethylsilyl derivatives. Galactose was found to be the major component in the fractions of all the species examined and glucose was present as a minor component in 15 of the species. From the results it was possible to calculate the MGDG/DGDG ratio.

Enzymatic acylation of steryl glycoside

Summary A soluble protein fraction obtained from leaves of Vicia faba catalyzes the acylation of steryl glycoside to acyl steryl glycoside by acyl groups originating from galactolipids. Using semisynthetic alactolipids it was shown that both acyl groups from C-1 and C-2 of mono- and digalactosyl diglyceride are transferred to steryl glycoside. The same protein fraction was also active in the formation of acyl galactosyl diglyceride. Using the same semisynthetic galactolipids as above it was demonstrated by mass spectrometry that during formation of acyl galactosyl diglyceride the acyl groups from the donor molecules are transferred exclusively to the galactose moiety of the accepting monogalactosyl diglyceride, its diglyceride portion remaining unaltered. After working out an assay based on the transfer of tritiated oleoyl groups from digalactosyl diglyceride to steryl glycoside it was shown that most of the soluble activity in leaf homogenates was not localized in chloroplasts.

Biosynthesis of galactosyl diglycerides by non-green fractions from chloroplasts

When either mitochondria, chloroplast stroma lamellae, or osmotically shocked chloroplasts were centrifugea through sucrose gradients, zones were always obtained at the 0.6 M–0.9 M boundary which were highly active in galactosyltransferase. These activities did not coincide with maxima for chlorophyll or cytochrome c oxidase activity. A second chlorophyll-free fraction was obtained at lower density, showing high galactosyltransferase activity when incubated after isolation. The results indicate that the highly active fractions originate from chloroplast envelopes.

Chemistry and biosynthesis of plant galactolipids.

Together with sulphoquinovosyl diglyceride (sulpholipid) the galactosyl diglycerides (galactolipids) are the glycolipids occurring in the photosynthetic tissue of algae and higher plants. In higher algae and plants they are mainly confined to the chloroplasts (1, 76, 108) where they form a structural part of the thylakoid membranes. Apart from this structural function in chloroplasts several other functions have been attributed to the galactolipids. These vary from a function as a carbohydrate reservoir to a function in the electron transport chain in photosynthesis. This review is intended to summarize the present knowledge of the synthetic and degradative chemistry of the galactolipids and of their functions in the photosynthesis of algae and higher plants.

Lipids of cassava tubers (Manihot esculenta crantz)

AbstractThe flour from cassava tubers contains about 2.5% of lipids, of which only half is extractable with conventional solvent systems. Extractable lipids are mainly polar in character, the principal group of components being galactosyl diglycerides. A new galactolipid, tetragalactosyl diglyceride, is described for the first time. The component fatty acids are relatively saturated in character in comparison with those of other structural lipids, such as those of the potato.

The biosynthesis and concentration of galactosyl diglyceride in glial and neuronal enriched fractions of actively myelinating rat brain.

Abstract—In continuation of our studies on the association of the galactosyl diglycerides of brain with myelination, we have measured the biosynthesis and concentration of these glyceride glycolipids, in oligodendroglial, astroglial, neuronal, and myelin enriched fractions from brains of rats of postnatal age 16, 19 and 29 days. The relative purity of cell fractions and myelin derived from 50 to 60 brains of each age‐group was checked by phase contrast microscopy and 2′,3′‐cyclic nucleotide‐3′‐phosphohydrolase activity. The relative purity was comparable to that reported by other investigators for cell fractions from bovine brain. Of the three cell types, the oligodendroglia had the highest and the neurons had the lowest capacity to enzymatically synthesize and to accumulate monogalactosyl diglyceride. The amount of monogalactosyl diglyceride found in myelin compared to that found in oligodendroglial fraction greatly increased during development between 16 and 29 days of age. The biosynthesis of galactosyl ceramide but not glucosyl ceramide was highest in oligodendroglial enriched cell fraction. However, ceramide glucosyl‐transferase activity, which was greatly affected by the method used for cellular separation, was highest in a microsomal fraction derived from grey matter. Our results support the contention that the oligodendroglial cells are the site of synthesis of myelin constituents of the central nervous system, and that there is a temporal relationship between this site of synthesis and the site of deposition (myelin).

Characterization and enzymatic synthesis of acyl galactosyl monoglyceride

An unknown lipid was isolated from leaf homogenates. The glycolipid is slightly more hydrophobic than monogalactosyi diglyceride, but composed likewise of giycerol, galactose and fatty acids in a molar ratio of 1:1:2. By NMR and mass spectroscopy the structure was determined to be 1′-O- acyl-3′-O-(6-O- acyl-β- d- galactopyranosyl) -sn- glycerol . For comparison this compound has also been prepared semisynthetically. Enzymatic experiments with radioactive substrates showed that in vitro acyl galactosyl monoglyceride can originate from monogalactosyl monoglyceride by accepting an additional fatty acid, which is derived either from another molecule of monogalactosyl monoglyceride or from digalactosyl diglyceride. These reactions resemble those involved in the formation of acyl galactosyl diglyceride.