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At least 19 recordsLinked to original sources

Cholesterol interacts with lactosyl and maltosyl cerebrosides but not with glucosyl or galactosyl cerebrosides in mixed monolayers.

Pure and mixed monolayers of mono- and dihexoside cerebrosides with cholesterol have been characterized at the air/water interface. Cholesterol oxidase was used as a reporter enzyme for the cholesterol-cerebroside interaction in the mixed monolayers. The cerebrosides either were derived from bovine brain extracts or were synthetic. The dihexoside cerebrosides were synthesized by coupling of the hepta-O-acetyl-alpha-lactosyl- or maltosylphosphoramidates with D-erythro-N-acylceramides in dichloromethane, in the presence of trimethylsilyl triflate and molecular sieves, followed by hydrolysis of the acetate-protecting groups. All of the bovine-brain-derived cerebrosides [galactosyl cerebroside (GalCer, types I and II), glucosyl cerebroside (GlcCer), and lactosyl cerebroside (LacCer)] had very condensed force-area isotherms (compressibility values of 3-5 x 10(-3) m/mN at 20 mN/m), as did the synthetic N-stearoylmaltosylceramide (N-18:0 MaltCer). Shorter-chain synthetic cerebrosides (N-8:0 LacCer and N-8:0 MaltCer) had more expanded isotherms, with compressibility values of 15-17 x 10(-3) m/mN. When cholesterol was included in mixed monolayers of monohexoside cerebroside, it did not induce significant condensation of packing (indicating that cholesterol did not increase the order of the acyl chains). However, with dihexoside cerebrosides, a cholesterol-induced condensing effect was observed, which amounted to a 11-19% reduction in the observed mean molecular area. When cholesterol oxidase was used to titrate the stoichiometry of cholesterol/cerebroside in mixed monolayers, at which pure cholesterol clusters appeared, it was observed that in monohexoside cerebroside monolayers cholesterol clusters were present even below a 1:1 molar stoichiometry.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[Reptile brain cerebrosides and cerebroside sulfates].

Studies have been made on the content of cerebrosides and cerebroside sulfates, as well as on their fatty acid composition in the brain of reptiles, subclass Anapsida (tortoises Emys orbicularis and Testudo horsfieldi) and subclass Lepidosauria (lizards Agama caucasica, A. sanguinolenta, Phrynocephalus mystaceus and snake Natrix tesselata). Total content of cerebrosides and cerebroside sulfates is higher in the brain of Lepidosaurians than in that of Anapsids. In the brain of tortoises, the content of cerebroside fraction with hydroxy fatty acids is significantly higher than of the fraction with normal fatty acids, which is also typical of the brain of homoiothermic mammals and birds. In the brain of Lepidosaurians, concentration of hydroxycerebrosides is considerably lower than of cerebrosides with normal fatty acids, which is similar to lower vertebrates -- amphibians and fishes. Low content of hydroxycerebrosides was found in all the Lepidosaurians investigated, irrespectively of their ecological conditions, being therefore dependent on their phylogenetic position. The composition of fatty acids, both normal and hydroxyderivates, as well as that of glycolipids from the brain of Anapsids and Lepidosaurians is essentially similar. However, some interspecific differences were noted in the pattern of fatty acids of cerebrosides and cerebroside sulfates of the brain, which concern the content of saturated and long chain fatty acids.

Animals↗

[Certain physical parameters of cerebroside and phospholipid-cerebroside membranes].

Study of some electric properties of bilayer membranes made of cerebrosides and phospholipid-cerebroside mixture has shown that the capacity of cerebroside film is lower than that of lecithin-cerebroside and phospholipid-cerebroside ones (0.22 +/- 0.01 mkf/cm2 and 0.28 +/- 0.01 mkf/cm2 respectively). The membranes had small cation selectivity. It is stated that conductivity of cations of mixed phospholipid-cerebroside membrane is two orders, and of cerebroside three orders higher than that of phospholipid bilayers. Conductivity of the films under study depends on the medium pH. By means of fluorescent probes cerebrosides were found capable of changing the conformation of phospholipid membranes.

Calcium↗

[Content of phospholipid, cerebroside and cerebroside sulfate in the central nervous system of mice with acute experimental viral demyelination].

A study was made of the content of phospholipids, cerebrosides and cerebroside sulfates in the central nervous system of mice with experimental acute viral encephalomyelitis. No considerable changes in phospholipid content were revealed. A significant drop in the content of cerebrosides and cerebroside sulfates was defected in the CNS, being more pronounced in the spinal cord of sick animals. The reduction in the content of glycolipids can be explained by myelin disintegration and by the effect of viruses on the olygodendrocytes in which cerebrosides and cerebroside sulfates are synthesized.

Acute Disease↗

Activator protein required for the enzymatic hydrolysis of cerebroside sulfate. Deficiency in urine of patients affected with cerebroside sulfatase activator deficiency and identity with activators for the enzymatic hydrolysis of GM1 ganglioside and globotriaosylceramide.

Urine specimens from two sibs affected with cerebroside sulfatase activator deficiency were examined to ascertain whether the deficiency of the supplementary activator protein required for the enzymatic hydrolysis of cerebroside sulfate was also evident in urine. Material from chromatographic fractionations was examined for the activator activity to avoid ambiguities resulting from protein inhibition. There were substantial deficits in all chromatographic fractions corresponding to activator-containing fractions of control urines. Since patient urines contained elevated amounts of lactosylceramide, digalactosylceramide, and globotriaosylceramide and since similarities between activators for cerebroside sulfate and GM1 ganglioside hydrolyses had been noted previously, the chromatographic fractions were also examined for activators in other glycosphingolipid hydrolase systems. There was coincidence of activators for the GM1 ganglioside/beta-galactosidase and the globotriaosylceramide/alpha-galactosidase A reactions with the cerebroside sulfatase activator in control urine fractions, and the patients' urines were deficient in activator activities for the three reactions. Identity of the three activators was suggested and antiserum to purified GM1 ganglioside activator was used to test this possibility. There were depressed levels of cross-reacting material in fractions of patient urines by Ouchterlony double diffusion and in unfractionated urine by enzyme-linked immunosorbent assay. Purified activators for the cerebroside sulfate and GM1 ganglioside systems showed lines of identity with no spurring on Ouchterlony double diffusion, identical mobility on immunoelectrophoresis, and similar stimulatory activities toward hydrolysis of the three glycosphingolipid species by their respective enzymes. Finally, the three activator activities were retained by anti-GM1-activator IgG coupled to Sepharose 4B. The results suggest strongly that the same protein entity serves as activator for the enzymatic hydrolysis of cerebroside sulfate, GM1 ganglioside, and globotriaosylceramide.

Animals↗

The cerebroside sulfate activator from pig kidney: derivitization, cerebroside sulfate binding, and metabolic correction.

Highly purified cerebroside sulfate activator from pig kidneys was characterized by a number of chemical and biological procedures. Methods for chemical modifications were evaluated in an attempt to obtain biologically active derivatives. Iodination, dabsylation, and to a lesser degree reductive methylation provided useful products with good retention of cerebroside sulfate activator activity. Other procedures resulted in largely inactive derivatives or losses in both protein and biological activities. Attempts at renaturation of cerebroside sulfate activator subjected to various denaturing conditions appeared to be successful in many instances, but it was uncertain if the protein structure had actually been disrupted. The binding of cerebroside sulfate by activator was estimated by gel filtration under conditions similar to those of its assay. The formation of a relatively stable 1:1 complex was observed, collaborating results with the human protein. The complex was stable enough to be isolated and shown to be an efficient substrate for arylsulfatase A. The effectiveness of the pig kidney cerebroside sulfate activator for correcting the metabolic defect in activator-deficient human fibroblasts was compared with human materials. The pig kidney protein was taken up more efficiently by the cells and resulted in a better metabolic correction than material from human liver, but was somewhat less effective than a preparation from human urine.

Animals↗

Neuritogenic cerebrosides from an edible Chinese mushroom. Part 2: Structures of two additional termitomycesphins and activity enhancement of an inactive cerebroside by hydroxylation.

Termitomycesphins E and F, novel cerebrosides that are hydroxylated around the middle of the long-chain base (LCB), have been isolated from the edible Chinese mushroom Termitomyces albuminosus (Berk.) Heim. ('Jizong' in Chinese) together with termitomycesphins A-D, and shown to induce neuronal differentiation in rat PC12 cells. Their stereostructures have been determined based on their chemical derivatization and spectroscopic analysis. The major cerebroside obtained from the same mushroom was not hydroxylated around the middle of the LCB and was inactive against PC12 cells, suggesting the importance of the extra hydroxyl group on LCB. The Di- and tetrahydroxylation of this inactive cerebroside resulted in the enhancement of its neuritogenic activity.

Agaricales↗

Effect of liposomes containing cerebroside and cerebroside sulfate on cytoskeleton of cultured oligodendrocytes.

Oligodendrocytes (OLs) and the myelin produced by them are enriched in two glycosphingolipids, galactosylceramide (GalC) and its sulfated form, cerebroside sulfate (CBS). We showed earlier that these two glycolipids in opposed liposomal membranes or in methanol solution can adhere to each other. Here we have examined the potential effect of an interaction between GalC/CBS in apposed membranes of oligodendrocytes (OLs) by incubating cultured OLs with GalC/CBS-containing liposomes and observing the effect on the membrane sheets produced by OLs and on the distribution of OL constituents using fluorescent antibodies and confocal microscopy. The GalC/CBS-containing liposomes caused redistribution or a decrease in the density of anti-GalC and anti-MBP staining but had no effect on the density or distribution of staining by anti-PI(4,5)P(2) that remained uniformly distributed in the membrane sheets. There was no apparent change in the area of the membrane sheets nor in the amount of MBP in OL membranes, as determined by slot blots. In addition, the GalC/CBS-containing liposomes caused depolymerization of microtubules and actin filaments suggesting that the interaction of GSL-containing liposomes with the extracellular surface of the OL caused transmission of a signal across the membrane. Because these two glycolipids can adhere to each other across apposed membranes, the liposomal glycolipids may be interacting with a GalC/CBS-enriched signaling domain in the OL plasma membrane.

Animals↗

Divalent cation-mediated interaction between cerebroside sulfate and cerebrosides: an investigation of the effect of structural variations of lipids by electrospray ionization mass spectrometry.

Divalent cations mediate a carbohydrate-carbohydrate association between the two major glycolipids, galactosylceramide (GalCer) and its sulfated form, cerebroside sulfate (CBS), of the myelin sheath. We have suggested that interaction between these glycolipids on apposed extracellular surfaces of myelin may be involved in the stability or function of this multilayered structure. A mutant mouse lacking galactolipids because of a disruption in the gene that encodes a galactosyltransferase forms myelin that initially appears relatively normal but is unstable. This myelin contains glucosylceramide (GlcCer) instead of GalCer. To better understand the role of GlcCer in myelin in this mutant, we have compared the ability of divalent cations to complex CBS (galactosyl form) with GlcCer or GalCer in methanol solution by using positive ion electrospray ionization mass spectrometry. Because both the alpha-hydroxylated fatty acid species (HFA) and the nonhydroxylated fatty acid species (NFA) of these lipids occur in myelin, we have also compared the HFA and NFA species. In addition to monomeric Ca2+ complexes of all three lipids and oligomeric Ca2+ complexes of both GalCer and GlcCer, Ca2+ also caused heterotypic complexation of CBS to both GalCer and GlcCer. The heterotypic complexes had the greatest stability of all oligomers formed and survived better at high declustering potentials. Complexes of CBS with GlcCer were less stable than those with GalCer. This was confirmed by using the free sugars and glycosides making up the carbohydrate headgroups of these lipids. HFA species of CBS and GalCer formed more stable complexes than NFA species, but hydroxylation of the fatty acid of GlcCer had no effect. The ability of GlcCer to also complex with CBS, albeit with lower stability, may allow GlcCer to partially compensate for the absence of GalCer in the mouse mutant.

Calcium↗

Comparison of the cerebroside sulphatase and the arylsulphatase activity of human sulphatase A in the absence of activators.

A cerebroside sulphatase (cerebroside-3-sulphate 3 sulphohydrolase, EC 3.1.6.8) assay based on radio thin-layer chromatography is described. The substrate was labelled by the catalytic addition of tritium to cerebroside sulphate. Using this assay the cerebroside sulphatase activity of sulphatase A (Aryl-sulphate sulphohydrolase, EC 3.1.6.1) from human liver and kidney in the absence of activators was investigated. The pH optimum of this reaction depends on the buffer concentration, being pH 4.5 at 50 mM and 5.3 at 10 mM sodium formate. With the latter concentration the apparent Km for cerebroside sulphate is 0.06 mM; SO2-4 and nitrocatechol sulphate inhibit noncompetitively with a Ki of 4.51 mM for Na2SO4 and 0.43 mM for nitrocatechol sulphate. The cerebroside sulphatase activity of sulphatase A is highly dependent on the ionic strength. The optimum sodium formate concentration is 10 mM, and the cerebroside suophatase activity decreases rapidly with increasing buffer concentration. The same concentration dependence is observed in the inhibitory effect of cerebroside sulphate on the arylsulphatase reaction. The inhibition decreases at increasing buffer concentrations, becoming an activation at 70 mM sodium formate. The progress curve of the cerebroside sulphatase reaction shows a deviation from linearity similar to that of the arylsulphatase reaction. Investigation of the effect of preincubation with cerebroside sulphate on the arylsulphatase activity of the enzyme shows that cerebroside sluphatase activity and inactivation of the enzyme by cerebroside sulphate occur simultaneously. These observations are interpreted as supporting the assumption that cerebroside suophate and arylsulphates are degraded at an identical active site on the same enzyme. Differences in the properties of the cerebroside sulphatase and the arylsulphatase reaction of the enzyme may be attributed to the differences in the physiocochemical state of the two substrates.

Binding Sites↗