Cerebrosides mixture

The effect of toxins such as melittin (from the honey-bee venom), myotoxin a, and cardiotoxin (from the snake venom) was investigated by vibrational spectroscopy (Pezolet et al., 1982 Faucon et ah, 1983 Liddle and Tu, 1985 Lafleur et ah, 1987). Monitoring the Raman intensity ratio I(1060)/I(1080) indicated that the lipid/melittin assemblies in DPPC are characterized by a high conformational order, little intermolecular chain-chain interaction, and a low cooperativity of the gel-like liquid crystalline phase transition. The effect of ricin, a toxic lectin, on DPPC and DPPC-cerebroside mixtures was studied by Raman and IR spectroscopy. It was suggested that ricin mainly interacts with the interfacial domains of the bilayers (Picquart et ah, 1989). 

Methanolysis of a cerebroside mixture and further analysis of the methanolysis products are helpful for identifying all the fatty acids and long-chain bases that contribute to the complexity of the cerebrosides mixture. 

Two new phytosphingosine-type cerebrosides mixtures (45 and 46) containing iV-acetylglucosamine were isolated from the marine sponge Oceanapia sp. (Fig. 16) [31 ]. They proved to be new variants of iV-acetylglucosamine-containing... 

FIGURE 16 New cerebrosides mixtures (45 and 46) from the sponge Oceanapia sp. 

Komori et al. (555) reported the isolation of a cerebroside mixture (987) and two nucleosides, thymine desoxyribonucleoside (988) and uracil desoxyribonucleoside (989), from Acanthaster planci. Structure elucidation was based on and C-NMR spectrometry as well as on El- and FD mass spectrometry. Similar cerebroside mixtures which showed nearly identical IR-spectra could be extracted from Luidia qui naria and Astropecten latespinosus. The mycosporine-like amino acids (990-994) have been obtained from alcoholic extracts of the starfish Asterina pectinifera 656). 

A recent search for general and specific elicitors from L. maculans demonstrated that the phytotoxins sirodesmin PL (1) and deacetylsirodesmin PL (2) are general elicitors since both induced the production of phytoalexins in resistant brown mustard and in susceptible canola [31]. Furthermore, two specific elicitors, a mixture of cerebrosides C (13) and D (14), were reported from mycelia of liquid cultures of L. maculans virulent on canola (Fig. 9.5) [19]. Previously, cerebrosides C (13) and D(14) were reported from a number of phytopathogenic fungi and were reported to induce the production of phytoalexins in rice plants and disease resistance to the rice blast fungus [32]. 

Although cerebroside sulfate has been reported to interact strongly with opiates C14-16), enkephalin has so far shown no significant binding in the present type of experiment to an egg lecithin C27 mg) - sulfatide (25 mg) mixture at pH 6.3 and 7.1. Further studies are currently underway with this system. 

The hepatopancreas of H. schlegelii was found to contain an unusual cerebroside, a mannosylceramide, isolated from the monohexosylceramide fraction by t.l.c. on borate-impregnated silica gel.265 Its structure was shown to be /3-D-mannosylceramide, whose major sphingosine base is 4-sphingenine, and the fatty acids constitute a mixture of normal (77% of the total acids) and a-hydroxy acids, with hexadecanoic acid preponderant (43.7% of the total acids).265... 

Prepare a 5 mg/ml liposome construction in 20 mM sodium phosphate, 0.15 M NaCl, pH 7.4, containing, on a molar ratio basis, a mixture of PC cholesterol PG other glycolipids of 8 10 1 2. The other glycolipids that can be incorporated include phosphatidyl inositol, lactosylceramide, galactose cerebroside, or various gangliosides. Other liposome compositions may be used, for example, recipes without cholesterol, as long as a periodate-oxidizable component... 

Treatment with galactose oxidase. Oxidation of myelin with galactose oxidase was performed as described previously for similar oxidation of rat spinal cord preparations (4). Typically, myelin containing 0.2-1.1 mg protein is incubated with 100-500 units of galactose oxidase in 1-3 ml of phosphate buffer (10-100 mM, pH 7.2-7.4) with or without catalase. After the incubation at room temperature to 30°C for the duration of 30 min to overnight, myelin is recovered by centrifugation, washed, and lyophilized. Total lipids were extracted from the dried residue and the oxidized cerebroside as well as unaltered cerebrosides were analyzed as described above. Alternatively, the incubation was stopped by the addition of 5 volumes of chloroform/methanol (2/1, v/v) and mixed. The lower layer after centrifugation of the mixture is washed and then evaporated to dryness, and the total lipids obtained were analyzed as described above. 

Oxidation of myelin surface cerebrosides by galactose oxidase. Fig. 4 shows silica HPLC of a mixture containing benzoylated-non-hydroxy and hydroxycerebroside and benzoylated derivatives of 2,4-dinitrophenylhydrazone of oxidation products from nonhydroxy- and hydroxycerebroside. Standard curves of two 6-dehydro-derivatives were shown in Fig. 5. These standard curves demonstrate that the response of the benzoylated dinitrophenylhydrazones are linear between 0.025 nmol and 0.6 nmol. Since cerebrosides containing 5 nmol can be determined without tailing to these peaks, this method should allow the determination of as little as 0.5% of the oxidation product. The fact that each curve intersects 0 point in both the abscissa and ordinate indicates that even smaller amounts of these compounds can be detected by this technique. 

To examine whether the enzyme is active under the same conditions, we coated 0.1 mg each of nonhydroxy- and hydroxycerebrosides on 10 mg Celite (Analytical grade) and incubated it with 100 units of galactose oxidase for 60 min at room temperature. The result indicated that 5.6 nmol and 3.5 nmol each of nonhydroxy and hydroxycerebrosides (approximately 4.6 and 3.0% each were oxidized. Oxidation of the same cerebrosides by the same galactose oxidase in a tetrahydrofuran/water mixture as described by Radin (9) resulted in nearly complete oxidation. 

Figure 8. Field desorption mass spectrum obtained at 22 ma for a mixture of cerebrosides from bovine brain. Assignments of MH are discussed in the text and...

With bilayer lipid membranes it is not possible to achieve a fully asymmetric arrangement of head groups or chains. There is no apparent reason why all the molecules of two independent layers should only concentrate in one layer. Nevertheless, a little asymmetric distribution is found in vesicles made of lipid mixtures. Cerebroside sulfate, an anionic monoglycosyl ceramide was, for example, added exclusively to the outer surface of a performed DPPC vesicle (see Scheme 2.2) which was quantitized by the metachromatic effect of acridine orange. 

Besides phrenosin and kerasin, two further cerebrosides, namely, nervon and oxynervon, were isolated from human-brain material by fractional recrystallization. These substances proved to be mixtures of many cerebrosides, and not pure compounds.71... 

The cerebroside fractions proved not to be pure compounds, but were mixtures of compounds having similar features of chemical structure. The differences between the single compounds in each group reside mainly in the chain length of the fatty acids in amide linkage. 

The diastereoisomeric configuration of the sugar-free cerebrosides (ceramides) was determined by Carter and coworkers,80 and found to be erythro, in accordance with the structure of sphingosine, which is isolated after drastic hydrolysis of sphingolipid mixtures or purified cerebrosides with acid. 

The mechanically fragmented brain or spinal cord was dehydrated with acetone, as in the isolation of cerebrosides.7 Gangliosides are present in the water-soluble fraction they were recognized by color reactions (for example, Bial s orcinol reaction) based on the presence of sialic acid.159 The ganglioside mixture may be purified by partition... 

Cerebrosides have been isolated from Phycomyces blakeslearus (3), a fungus often found on animals dung, by extraction of mycelia with acetone and chloroform/methanol mixtures and purified on a silicic acid column, followed by a Florisil column. The bases obtained after hydrolysis were all phytosphingosine homologs ranging in length from C17 to C22. Palmitic,stearic, oleic, linoleic and hydroxy palmitic acids were the major fatty... 

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