Types Of Ceramides Research Articles

Lipid remodeling leads to the introduction and exchange of defined ceramides on GPI proteins in the ER and Golgi of Saccharomyces cerevisiae.

Previous experiments with Saccharomyces cerevisiae had suggested that diacylglycerol-containing glycosylphosphatidylinositols (GPIs) are added to newly synthesized proteins in the endoplasmic reticulum (ER) and that ceramides subsequently are incorporated into GPI proteins by lipid remodeling. Here we prove this hypothesis by labeling yeast cells with [3H]dihydrosphingosine ([3H]DHS) and showing that this tracer is incorporated into many GPI proteins even when protein synthesis and, hence, anchor addition, is blocked by cycloheximide. [3H]DHS incorporation is greatly enhanced if endogenous synthesis of DHS is inhibited by myriocin. Labeled GPI anchors contain three types of ceramides which, based on previous and present results, are identified as DHS-C26:0, phytosphingosine-C26:0 and phytosphingosine-C26:0-OH, the latter being found only on proteins which have reached the Golgi. Lipid remodeling can occur both in the ER and in a later secretory compartment. In addition, ceramide is incorporated into GPI proteins a long time after their initial synthesis by a process in which one ceramide gets replaced by another ceramide. Remodeling outside the ER requires vesicular flow from the ER to the Golgi, possibly to supply the remodeling enzymes with ceramides.

Successful Incorporation of Pseudo-Ceramides into Emulsions at Effective Concentrations

The incorporation of pseudo-ceramide (SLE), analogous in structure to natural occurring ceramide Type II, into an emulsion for skincare treatment was investigated. As SLE is water insoluble and not sufficiently oil soluble, resulting concentrations in emulsions were only 1.25%—too low for skin treatment. Stable lamellar structures formed with stearic acid did not have sufficient affinity for water to allow emulsification. The water binding capacity was increased by modifying stearic acid with polyoxyethylene (C18EOn). When using stearic acid with 5 to 25 POE units, excess water would initiate emulsification (liquid crystalline emulsification). The interaction between the polar groups of C18EOnand SLE prevents SLE from crystallizing out. Replacing stearic acid with cholesterol resulted in a much smaller droplet size due to a change in fluidity in the hydrophobic portion of the lamellar structure, thus further increasing the stability. Employing C18EOnor POE-modified cholesterol, it was possible to incorporate up to 18.1% of SLE into an emulsion.

Formation of Stable Lamellar Structures with Pseudo-Ceramide

One of the functions of the intercellular lipids of the stratum corneum is to control the permeation of molecules. Their main component being ceramides, the pseudo-ceramide sphingolipid E (SLE), which is similar in structure to natural ceramide type II, is considered a potential drug carrier. Therefore, the internal structure of SLE was investigated. SLE by itself forms a meta-stable lamellar structure that gradually crystallizes out as confirmed by X-ray analysis. With reference to naturally occurring lamellar structures of intercellular lipids, stearic acid was found to be able to stabilize the lamellar structure of SLE, when added within a defined concentration range. It was further demonstrated that both the hydrophobic and the hydrophilic portions of the stearic acid molecule contribute to the stability. Short-chained fatty acids lacking a long hydrophobic chain resulted in unstable structures. Likewise, the addition of less polar derivatives of stearic acid (stearic alcohol and hexadecane, reps.) could not maintain a lamellar structure. Only the strong hydrogen bonds between the carboxy group of stearic acid and the amido-carbonyl group of SLE produced a stable lamellar structure as was confirmed by FT-IR analysis.

Structure of stratum corneum lipids characterized by FT-Raman spectroscopy and DSC. I. ceramides

Fourier transform Raman spectroscopy and differential scanning calorimetry (DSC) were used to study ceramides type IV as a model substance for the ceramides fraction of stratum corneum lipids. The major part of the Raman spectrum consists of bands owing to the alkyl chain, but there are also bands which belong to the head group of the ceramides. The appearance of the conformationally dependent bands indicates the ordered structure of the hydrocarbon chains. The temperature dependence of the conformationally sensitive bands in the CH 2 stretching region (2800–2975 cm −1), in the chain C-C stretching region (1050–1150 cm −1), and in the low frequency region below 300 cm −1 is used to estimate the degree of order in terms of the relative population of trans and gauche conformers. The C-C stretching modes at 1063 cm −1 and 1130 cm −1 (trans conformation) and the asymmetric CH 2 stretching mode at 2880 cm −1 decrease rapidly near the phase transition temperature and disappear in the liquid state. The temperature and width of the phase transition, derived from Raman data, are similar to these of the DSC study.

Thermotropic behavior of stratum corneum lipids containing a pseudo-ceramide.

The mechanism of the self-assembly of the lamellar structure of natural stratum corneum lipids (SCL) has been a subject of considerable interest. We have examined this question by using a synthetic pseudo-ceramide (sphingolipid E, SLE) which was analogous to the naturally occurring ceramide type 2. The thermotropic properties and the structural characteristics of SLE, together with other main components of SCL, fatty acids, and cholesterol, were investigated by differential scanning calorimetry and X-ray analysis. A mixture of SLE and stearic acid was in a stable alpha-form having a lamellar structure, which is very similar to that of natural SCL. However, lipid mixtures in which stearic acid were replaced by oleic acid did not form lamellar structures, and existed in the crystalline states. This indicates that the stable bilayer formation of the natural SCL is strongly dependent on the molecular fatty acid structure. Moreover, incorporation of cholesterol (0-50%) into equimolar mixtures of SLE/stearic acid and of SLE/oleic acid caused a marked decrease of melting entropies, while the aggregation states of both systems were not changed. This effect of cholesterol can be attributed to the disorder of the molecular packing. These results suggest that the hydrophobic interactions between the SCL are important for bilayer formation as are the hydrophilic interactions between the polar groups.

Enzymatic formation of plant cerebroside: properties of UDP-glucose: ceramide glucosyltransferase in radish seedlings.

The activity of cerebroside synthase (UDP-glucose: ceramide glucosyltransferase) was found in the microsomal fraction of radish hypocotyls, and was studied. One % of the radioactivity due to UDP-[3H]glucose added to the membrane fraction was incorporated into cerebroside within 60 min. Optimum pH and temperature of the activity were pH 7.8 and 30 degrees C, respectively. No metal ions enhanced the cerebroside synthase activity, dissimilar to that in animal tissues. The apparent Km for UDP-glucose was approximately 200 microM. The same activity was also observed in radish roots and cotyledons, but proportions of UDP-[3H]glucose incorporation were slightly lower than that in hypocotyls. Exogenous ceramide species having trihydroxy sphingoid bases, which were major ceramide components of radish cerebrosides, usually stimulated cerebroside formation in microsomal fractions from radish seedlings, while any ceramide types having dihydroxy sphingoid bases were ineffective on the glucosylation reaction. It was assumed, therefore, that cerebroside synthase in radish seedlings would have substrate selectivity for ceramide species.

Characterization of the binding of propionibacterium granulosum to glycosphingolipids adsorbed on surfaces. An apparent recognition of lactose which is dependent on the ceramide structure.

The binding properties of a strain of Propionibacterium granulosum derived from human skin was investigated with reference to glycosphingolipids separated on thin layer chromatograms or coated in microtiter wells using externally (125I) and metabolically [( 35S]methionine) labeled bacteria. Binding was found to lactosylceramide (LacCer; Gal beta 1-4Glc beta 1-Cer) but not to glycolipids lacking the lactose sequence (i.e. Glc beta 1-Cer, Gal beta 1-Cer or Gal alpha 1-4Gal beta 1-Cer). In microtiter wells, binding occurred at 50 ng and became half-maximal at the theoretical value for a monomolecular layer of LacCer (i.e. 100-200 ng/well). The bacteria also bound to glycolipids with various substitutions (e.g. GalNAc beta 1-4, Gal beta 1-3GalNAc beta 1-4, Fuc alpha 1-2Gal beta 1-3GalNAc beta 1-4, Gal alpha 1-3, GlcNAc beta 1-3, Gal beta 1-3GlcNAc beta 1-3, Gal beta 1-4GlcNAc beta 1-3, and Gal beta 1-3(Fuc alpha 1-4)GlcNAc beta 1-3) at the Gal of LacCer, although only those species with GalNAc beta 1-4 or Gal beta 1-3GalNAc beta 1-4 were as active as LacCer itself. Glycolipids with other additions (e.g. Gal alpha 1-4 and NeuAc alpha 2-3) were negative. For unsubstituted LacCer, the binding required either a trihydroxy base or 2-hydroxy fatty acid, specifying the epithelial type of ceramide; LacCer composed of a dihydroxy base and nonhydroxy fatty acid was negative. This is interpreted as indicating that the proper presentation of the binding epitope depends on the ceramide structure. The relevance of this to biological membranes has not yet been established. Neither free lactose (up to 20 mg/ml) nor lactose-bovine serum albumin (5 mg/ml) prevented the binding of bacteria to LacCer, two facts that support the solid-phase binding data demonstrating a low affinity binding and the crucial importance of a particular lactose epitope.

Separation and characterization of hematosides with different sialic acids and ceramides from rat small intestine. Different composition of epithelial cells versus non-epithelial tissue and of duodenum versus jejunum-ileum.

The hematosides (sialyl-lactosylceramides) of rat small intestine were separated as their acetylated derivatives. The isolated fractions were characterized by mass spectrometry and degradative methods, and the two major fractions also by NMR spectroscopy. From these results hematosides with different sialic acid and ceramide type could be assigned to thin-layer chromatographic bands. This allowed a structural interpretation of the chromatographic patterns observed for different parts of the small intestine. Thus, epithelial cells of ileum contained only hematoside with N-glycoloylneuraminic acid. Duodenum lacked this compound and instead the epithelial cells contained hematoside with N-acetylneuraminic acid. In non-epithelial tissue or both duodenum and jejunum-ileum the major hematoside had N-acetyl-neuraminic acid. The hematosides of epithelial cells had ceramide containing 18 : 0 trihydroxy base combined with 16, 20, 22, 24 : 0, and 24 : 1 hydroxy fatty acids (major part) or non-hydroxy fatty acids. In the non-epithelial hematosides the ceramide consisted of 18 : 1 dihydroxy base combined with 16, 18, 20, 22, 24 : 0, and 24 : 1 non-hydroxy fatty acids.

Studies on glycosphingolipids of fresh-water bivalves. VI. Isolation and chemical characterization of neutral glycosphingolipids from spermatozoa of the fresh-water bivalve, Hyriopsis schlegelii.

The spermatozoa of the fresh-water bivalve, Hyriopsis schlegelii, had a complex spectrum of neutral glycosphingolipids. CDS, CTS, CTeS were isolated as minor components (together they accounted for 3% of the total neutral glycolipid fraction), while CMS and the glycolipids (Lipid I, II, and III) with larger saccharide chains that were previously characterized (1--4) occurred as major ones. The chemical structures were determined by employing exoglycosidases, partial acid hydrolysis and permethylation analysis. The proposed structures are as follows: Man alpha(1-3)Man beta(1-4)Glc-Cer for CTS, and Man alpha(1-3)[Xyl beta(1-2)]Man beta(1-4)Glc-Cer for CTeS. CTeS was the first example of a tetraglycosyl ceramide containing xylose. In another fraction, two types of diglycosyl ceramides were obtained as a mixture, and identified as Man beta(1-4)Glc-Cer and Gal beta(1-4)Glc-Cer, respectively. The long-chain base was predominantly composed of sphingosine, and the acyl groups were mainly of palmitate and stearate.

Blood group type glycosphingolipids from the small intestine of different animals analysed by mass spectrometry and thin-layer chromatography. A note on species diversity.

The total non-acid glycosphingolipids were isolated from the small intestine of cat, cod-fish, guinea-pig, hen, mouse, rabbit, and two strains of rat. The samples were analyzed by thin-layer chromatography and mass spectrometry and for immunological activity. Mass spectrometry of permethylated and LiAlH4-reduced permethylated derivatives allowed the interpretation of the structures (carbohydrate sequence and ceramide composition) of up to 9 glycolipid species in one mixture. The interpretation was facilitated by a temperature programming of the direct inlet probe, leading to a successive evaporation of glycolipid species mainly according to the number of sugars. The structures concluded could in most cases be assigned to the separate bands revealed by thin-layer chromatography. Antigenic determinants proposed by the spectra were settled by immunological analysis. Thus, Forssman glycolipid was identified in cat, guinea-pig, hen and mouse, blood group A glycolipids in cat, rabbit, and rat and blood group B glycolipids in rabbit and rat. No Lewis activity was found. Certain ceramide types were demonstrated to exist preferentially in some glycolipids. Globoside and Forssman glycolipids (globo series) had a less hydroxylated ceramide (one free hydroxyl) compared to most fucolipids and other glycolipids (two or three hydroxyls). In conclusion, glycolipid patterns of intestine vary between species, and individuals of the same species.

Changes in cerebroside synthetic activities of the brain with development of the rhesus monkey (macaca mulatta)

Cerebroside synthetic activities vary according to age in homogenates of the pons and cortical gray matter from brains of rhesus monkeys. The rate of utilization of uridine diphosphate (UDP) galactose and hydroxy fatty acid (HFA) ceramide for cerebroside synthesis by the pons was very low until 100 days after conception and reached a maximum at about 150 days (15 days before birth). This activity was very low in gray matter.There were marked effects of the type of ceramide and UDP sugar added, as well as of the origin of the brain homogenates from gray matter or pons on the quantity and type of cerebroside synthetized.

A Sphingolipid Having a Novel Type of Ceramide and Lacto-N-Fucopentaose III

Abstract A new sphingoglycolipid was isolated from human adenocarcinomas. The glycolipid had a novel ceramide which contained predominantly 4-hydroxysphinganine (phytosphingosine) and a high content of α-hydroxy fatty acids. The structure of the carbohydrate moiety was identified as O-β-galactosyl-(1 → 4)-[O-α-l-fucosyl-(1 → 3)]-O-β-(N-acetyl)glucosaminosyl-(1 → 3)-O-β-galactosyl-(1 → 4)-glucose, which was identical with that of lacto-N-fucopentaose III (Kobata, A., and Ginsburg, V., J. Biol. Chem., 244, 5496 (1969)). The precipitating antibody against this glycolipid was produced in rabbit, the antiserum was allowed to react specifically with this glycolipid but not with Lewis a or Lewis b glycolipid, and the precipitin reaction was inhibited by lacto-N-fucopentaose III.