Information

Difference between cerebroside and globoside


I have a general idea about their difference that cerebrosides have a single sugar while globosides have more than one sugars.

This is the structure of a ceramide (syphingosine and a fatty acid linked through amide linkage).

It's not clear to me that do cerebrosides have a single monosaccharide on only one -OH group of the syphingosine, two monosaccharides on each of the two -OH groups, or one oligosaccharide on only one -OH group.

Likewise I am not sure if globosides have a single oligosaccharide on only one - OH group of syphingosine, or two monosaccharides on each of the two -OH groups, or two oligosaccharides on each of the two -OH group.

If you have any knowledge about this, please share. Thanks.


This is Encyclopedia about cerebroside https://www.guidechem.com/dictionary_keys_cerebroside-p1.html and this is about globoside https://www.guidechem.com/dictionary_keys_globoside-p1.html https://en.wikipedia.org/wiki/Globoside I hope this can help you.


2.7: Fatty Acids

  • Contributed by E. V. Wong
  • Axolotl Academica Publishing (Biology) at Axolotl Academica Publishing

Unlike monosaccharides, nucleotides, and amino acids, fatty acids are not monomers that are linked together to form much larger molecules. Although fatty acids can be linked together, for example, into triacylglycerols or phospholipids, they are not linked directly to one another, and generally no more than three in a given molecule. The fatty acids themselves are long chains of carbon atoms topped off with a carboxyl group. The length of the chain can vary, although most are between 14 and 20 carbons, and in higher order plants and animals, fatty acids with 16 and 18 carbons are the major species.

Figure (PageIndex<13>). Fatty acids. (Top) Stearic acid is a fully saturated fatty acid with no carbon-carbon double bonds. (Bottom) Oleic acid is an unsaturated fatty acid.

Due to the mechanism of synthesis, most fatty acids have an even number of carbons, although odd-numbered carbon chains can also be generated. More variety can be generated by double-bonds between the carbons. Fatty acid chains with no double bonds are saturated, because each carbon is saturated with as many bonded hydrogen atoms as possible. Fatty acid chains with double bonds are unsaturated (Figure (PageIndex<13>)). Those with more than one double bond are called polyunsaturated. The fatty acids in eukaryotic cells are nearly evenly divided between saturated and unsaturated types, and many of the latter may be polyunsaturated. In prokaryotes, polyunsaturation is rare, but other modifications such as branching and cyclization are more common than in eukaryotes. A table of common fatty acids is shown below.

Myristic Acid 14:0 (14 carbons, no double bonds
Palmitic Acid 16:0
Stearic Acid 18:0
Arachidic Acid 20:0
Palmitoleic Acid 16:1
Oleic Acid 18:1
Linoleic Acid 18:2
Arachidonic Acid 2:4

There are significant physical differences between the saturated and unsaturated fatty acids due simply to the geometry of the double-bonded carbons. A saturated fatty acid is very flexible with free rotation around all of its C-C bonds. The usual linear diagrams and formulas depicting saturated fatty acids also serve to explain the ability of saturated fatty acids to pack tightly together, with very little intervening space. Unsaturated fatty acids, on the other hand are unable to pack as tightly because of the rotational constraint impoarted by the double bond. The carbons cannot rotate around the double bond, so there is now a &ldquokink&rdquo in the chain. Generally, double-bonded carbons in fatty acids are in the cis- configuration, introducing a 30-degree bend in the structure.

Figure (PageIndex<14>). Triglycerides. These lipids are formed by conjugation of a glycerol to three fatty acyl chains through ester bonds from each glycerol oxygen.

Fatty acids inside cells are usually parts of larger molecules, rather than free acids. Some of the most common lipids derived from fatty acids are triacylglycerols, phosphoglycerides, and sphingolipids. Triacylglycerols, as the name implies, is three fatty acid (acyl) chains connected to a glycerol molecule by ester bonds (Figure (PageIndex<14>)). Triacylglycerols, also known as triglycerides, may have fatty acids of the same (simple triacylglycerols) or varying types (mixed triacylglycerols). Mixtures of these are the primary long-term energy storage molecules for most organisms. Although they may be referred to colloquially as fats or oils, the only real difference is the degree of saturation of their constituent fatty acids. Mixtures with higher percentages of saturated fatty acids have a higher melting point and if they are solid at room temperature, they are referred to as fats. Triacylglycerol mixtures remaining liquid at room temperature are oils.

In human medicine, a common test for heart disease risk factors is measurement of triglyceride levels in the blood. Although various cell types can make and use triglycerides, most of the triglycerides in people are concentrated in the adipose tissue, which is made up of adipocytes, or fat cells, though liver is also a significant fat store. These cells have specialized to carry fat globules that take up most of the volume of the cell. When triglyceride levels in the blood are high, it means that fat is being produced or ingested faster than it can be taken up by the adipocytes.

Figure (PageIndex<15>). A phospholipid: the glycerol backbone (red) connects to two fatty acids and to a phosphate and polar head group.

Phospholipids (also called phosphoglycerides or glycerophospholipids), are also based on attachment of fatty acids to glycerol. However, instead of three fatty acyl tails, there are only two, and in the third position is a phosphate group (Figure (PageIndex<15>)). The phosphate group also attaches to a &ldquohead group&rdquo . The identity of the head group names the molecule, along with the fatty acyl tails. In the example Figure, 1-stearoyl refers to the stearic acid on the 1-carbon of the glycerol backbone 2-palmitoyl refers to the palmitic acid on the 2-carbon of the glycerol, and phosphatidylethanolamine refers to the phosphate group and its attached ethanolamine, that are linked to the glycerol 3-carbon. Because of the negatively-charge phosphate group, and a head group that is often polar or charged, phospholipids are amphipathic - carrying a strong hydrophobic character in the two fatty acyl tails, and a strong hydrophilic character in the head group. This amphipathicity is crucial in the role of phospholipids as the primary component of cellular membranes.

Figure (PageIndex<16>). Sphingolipids are based on the amino alcohol, sphingosine (A). Ceramides have a fatty acid tail attached, and a ceramide with a phosphocholine head group is a sphingomyelin (B). If the head group is a sugar, then the molecule is a cerebroside. (C)

Sphingolipids (Figure (PageIndex<16>)) are also important constituents of membranes, and are based not upon a glycerol backbone, but on the amino alcohol, sphingosine (or dihydrosphingosine). There are four major types of sphingolipids: ceramides, sphingomyelins, cerebrosides, and gangliosides. Ceramides are sphingosine molecules with a fatty acid tail attached to the amino group. Sphingomyelins are ceramides in which a phosphocholine or phosphoethanolamine are attached to the 1-carbon. Cerebrosides and gangliosides are glycolipids - they have a sugar or sugars, respectively, attached to the 1-carbon of a ceramide. The oligosaccharides attached to gangliosides all contain at least one sialic acid residue. In additional to being a structural component of the cell membrane, gangliosides are particular important in cell to cell recognition.

Lipids are vaguely defined as biological compounds that are insoluble in water but are soluble in organic solvents such as methanol or chloroform. This includes the fatty acid derivatives listed above, and it includes the final topic for this chapter, cholesterol. Cholesterol (Figure (PageIndex<17>)) is the major biological derivative of cyclopentanoperhydrophenanthrene, a saturated hydrocarbon consisting of four fused ring formations. It is an important component of plasma membranes in animal cells, and is also the metabolic precursor to steroid hormones, such as cortisol or b-estradiol. Plant cells have little if any cholesterol, but other sterols like stigmasterol are present. Similarly, fungi have their particular sterols. However, prokaryotes do not, for the most part, contain any sterol molecules.


Experimental procedures

Animals

All animal use procedures were in accordance with the NIH Guide for the Care and Use of Laboratory Animals and were approved by the University of North Carolina Institutional Animal Care and Use Committee. Male C57BL/6 J mice, 7 weeks of age, were obtained from Jackson Laboratories (Bar Harbor, ME, USA). At 8 weeks of age, these animals, weighing 24 ± 2 g, were placed on milled Purina Lab chow containing 0.2% cuprizone (bis-cyclohexanone oxaldihydrazone Sigma Chemical Co., St Louis, MO, USA) for 1–12 weeks prior to killing ( Hiremath et al. 1998 ). Additional animals were maintained on the cuprizone diet for 6 weeks, and then allowed to recover on a normal diet for an additional 1–6 weeks. Control animals were maintained on milled Purina lab chow.

Animals were killed at various times, and brains (including cerebellum and brainstem) were dissected. To assess rates of lipid synthesis, mice were injected intraperitoneally with 25 mCi 3 H2O and maintained for a 4-h period to allow for incorporation of label prior to killing (see Jurevics and Morell 1994 ). Blood samples were also obtained upon killing and used to prepare serum for determination of specific radioactivity of body water (assuming 0.95 µL of water/µL of serum). For RNA analysis, brains from parallel groups of animals were dissected, immediately frozen on dry ice, and stored at − 80°C prior to analysis.

Lipid extraction, separation, and quantification

Lipids were extracted by a modification ( Benjamins et al. 1976 ) of the method of Folch et al. (1957) . Analyses of cerebroside and cholesterol levels and synthesis rates were as described previously ( Jurevics and Morell 1994 Muse et al. 2001 ). In summary, an aliquot of the total lipid fraction was benzoylated and desulfated ( Nonaka and Kishimoto 1979 ) and then fractionated by HPLC on a silica column eluted with a gradient of isopropanol in hexane. Peaks containing benzoylated hydroxy and non-hydroxy fatty acid cerebrosides and sulfatides were detected by ultraviolet absorption at 230 nm and quantified against authentic standards ( Muse et al. 2001 ). Sterols were resolved from another aliquot of the total lipid fraction by reverse-phase HPLC on a C18 column, using isocratic elution with acetonitrile/isopropanol (97.5/2.5). Sterols were detected by ultraviolet absorption at 210 nm and quantified against authentic standards ( Jurevics and Morell 1994 ).

Measurement of in vivo lipid synthesis rates

Intraperitoneally injected 3 H2O rapidly equilibrates with cellular and other pools of body water ( Turley et al. 1981 Spady and Dietschy 1983 Jurevics and Morell 1994 ). With knowledge of the metabolic pathway for biosynthesis of a lipid, one can calculate how many hydrogen atoms present in the final product are derived from water. In the case of cerebroside, this is approximately 33 hydrogen atoms per molecule of cerebroside ( Muse et al. 2001 ). In the case of cholesterol, such calculations indicate incorporation of 22 hydrogen atoms from water into each molecule of cholesterol ( Andersen and Dietschy 1979 Dietschy and Spady 1984 Belknap and Dietschy 1988 ). With knowledge of the specific radioactivity of body water (obtained from a serum sample), radioactivity present in brain cerebroside or cholesterol can be recalculated as a molar amount of lipid newly synthesized since the time of injection of radioactive water. The actual calculation is trivial the number of moles of lipid synthesized is the radioactivity incorporated into the lipid divided by 16.5 (cerebroside) or 11 (cholesterol) times the specific radioactivity of body water.

Assay of mRNA species

Total RNA was isolated from half of each mid-sagittally sectioned brain. As described previously ( Toews et al. 1990 ), brains were homogenized in 4 mL of guanidinium isothiocyanate solution RNA was collected by centrifugation through 5.7 m cesium chloride and further purified by ethanol precipitation ( Chirgwin et al. 1979 ). RNA species were separated according to molecular weight on denaturing 0.8% agarose gels containing formaldehyde and then transferred to Zeta-Probe nylon blotting membranes (Bio-Rad Laboratories, Richmond, CA, USA). Filters were hybridized with 32 P-labeled cDNA probes synthesized using double-stranded polymerase chain reaction (PCR) methodology ( Jansen and Ledley 1989 ) for amplification of cDNA for myelin basic protein (MBP Roach et al. 1983 ), or single-stranded PCR methodology ( Bednarczuk et al. 1991 ) for amplification of cDNA for HMG-CoA reductase ( Day et al. 1989 ) and ceramide galactosyltransferase (CGT Stahl et al. 1994 ). Filters were washed and radioactivity in RNA was quantified using a Packard InstantImager electronic autoradiography system. Filters were also exposed to X-ray film to obtain a visual pattern of mRNA levels. To control for variability in sample handling, values obtained were normalized to the amount of ribosomal RNA in each lane, as assayed with a 32 P-end-labeled oligonucleotide specific to a defined sequence in the 28S subunit ( Hadjiolov et al. 1984 ).

Assay of MBP protein levels

Whole brain proteins were solubilized by homogenization in 1% sodium dodecyl sulfate (SDS) followed by boiling for 15 min. The insoluble residue obtained following centrifugation was discarded and the protein concentration of the SDS-soluble fraction was determined using a DC Protein Assay kit (BioRad, Hercules, CA, USA) per manufacturer's instructions. Aliquots of each extract containing approximately 3 µg protein were separated by SDS–polyacrylamide gel electrophoresis on precast 10–20% gradient Tricene gels (Invitrogen, Carlsbad, CA, USA), and then transferred to nitrocellulose membranes (Invitrogen). Membranes were blocked with 10% non-fat dried milk and then incubated with a monoclonal antibody against MBP (SMI 94 1 : 5000 Sternberger Monoclonals, Lutherville, MD, USA) overnight at 4°C. After washing, membranes were incubated with peroxidase-labeled goat anti-mouse IgG (1:2000, Vector Labs, Burlingame, CA, USA) for 1 h at room temperature. Levels of the 14.0-kDa MBP were determined by enhanced chemiluminescence utilizing ECL + Plus detection reagents (Amersham Pharmacia, Piscataway, NY, USA), and a ‘Storm 840’ Phosphoimager (Molecular Dynamics, Sunnyvale, CA, USA).

Statistical analysis

Single factor analysis of variance ( anova ) was performed on data generated in experiments using control and cuprizone-fed mice. Differences were considered significant at p < 0.05. Differences between groups at certain time points were analyzed by Student's t-test and considered significantly different at p < 0.05.


MATERIALS AND METHODS

Capture of house sparrows and measurement of cutaneous water loss

We mist netted 12 house sparrows Passer domesticus L. at the National Wildlife Research Center (22°15′N, 41°50′E) in Taif, Saudi Arabia, and 8 sparrows in Columbus (Ohio, USA, 40°00′N,83°10′W), during October–November 2003. Average ambient temperature at the time of the study was 20.7°C at Taif and 12.0°C at Columbus, Ohio. Sparrows at the Research Center where we captured them have water continuously available. Prior to measurements, sparrows were held in captivity for 1–2 days they were fed with a mixture of seeds, mealworms and egg yolk, and provided with water ad libitum.

We measured cutaneous water loss (CWL) using an open flow mask respirometry system (Tieleman and Williams,2002). Data for CWL of desert and mesic house sparrows are reported elsewhere (see Muñoz-Garcia and Williams,2005).

Extraction of covalently bound lipids

After measuring CWL, we sacrificed birds, and removed their skin. We then isolated the stratum corneum (SC) and extracted intercellular lipids following published procedures (Haugen et al.,2003 Muñoz-Garcia and Williams, 2005). The SC was stored in glass test tubes at–20°C under an atmosphere of nitrogen.

To confirm that all extracellular lipids had been extracted, we soaked the SC for each bird for 2 h in chloroform:methanol 1:2 (v/v). We then examined extracts for lipids using thin layer chromatography (TLC). No lipid bands were detected in our plates, indicating that all the intercellular lipids had been removed.

Next we searched for covalently bound lipids (CBL) on corneocytes by immersing the SC in 2 ml of 1 mol l –1 NaOH in 90% methanol at 60°C for 2 h (Wertz and Downing,1987). This mild alkaline hydrolysis breaks the ester bonds of lipids attached by an ester linkage to proteins(Wertz and Downing, 1987). We then adjusted the to pH 6 by adding 3 mol l –1 HCl, and added 2.5 ml of chloroform. The solution was then passed through a sintered glass filter, and centrifuged at 3000 g for 15 min. After a few minutes, the solution separated into two layers, an aqueous layer and an organic layer that contained any lipids. The organic phase was washed twice with distilled water to remove contaminants. The aqueous phase was mixed with 1 ml of chloroform to extract any lipids that might be in this phase, and recentrifuged at 3000 g for 10 min. We combined the organic fractions, and removed any remaining small particles by passing the solution through a PTFE filter, 0.45 μm pore size (Millex, Millipore Corp., Bedford,MA, USA). We dried the filtrates with a stream of nitrogen and stored them at–20°C. Prior to analysis of lipids, the extracts were re-constituted in 50 μl of chloroform:methanol (2:1, v/v) containing 50 mg l –1 of the antioxidant butylate hydroxytoluene, BHT.

Identification and quantitation of covalently bound lipids

We tested for CBL in the stratum corneum by using analytical thin layer chromatography (TLC) on 20 cm × 20 cm glass plates covered with silicic acid (0.25 mm thick, Adsorbosil-Plus 1, Alltech, Deerfield, IL, USA). Plates were prepared by developing them with chloroform:methanol (2:1, v/v) to the top, air drying them, and activating them for 30 min at 110°C. Then, we divided each plate in 10 mm wide lanes. We prepared standards with known concentrations of nonhydroxy fatty acid ceramides, galactocerebrosides,cholesterol and a mixture of free fatty acids, all purchased from Sigma (St Louis, MO, USA). The concentration of the standards varied from 0.3 to 10μgμl –1 , a range that spanned the concentration of lipids in our extracts. We loaded 5 μl of both standards and samples on to plates, both in duplicate, with a Teflon tipped Hamilton syringe. More polar lipids, such as ceramides and cerebrosides, were separated using a development of chloroform:methanol:water (40:10:1, v/v/v) to 8 cm from the bottom,followed by two developments with chloroform:methanol:acetic acid (190:9:1,v/v/v) to the top, and a final development with hexane:diethyl ether:acetic acid (70:30:1, v/v/v) to a half. For neutral lipids, such as free fatty acids,we developed plates with hexane to the top, followed by a development with toluene to the top, and a final development with hexane:diethyl ether:acetic acid (70:30:1, v/v/v) to half. After development, we sprayed plates with a solution of 3% cupric acetate in 8% phosphoric acid, placed them on aluminum hotplates and slowly raised the temperature to 160°C over a period of 30 min. The procedure charred the lipids, allowing their visualization.

Some of the lipids in our extracts migrated on TLC plates at a rate consistent with cerebroside standards. To confirm that these lipids were cerebrosides, we tested these bands for the presence of sugars by spraying plates with a mixture of 100 g of 2,4-dinitrophenylhydrazine in 100 ml phosphoric acid/ethanol (1:1, v/v). Then, we heated the plate at 110°C for 10 min. In the presence of sugars, 2,4-dinitrophenylhydrazine yields an orange color (Wall, 2005).

We also used high performance thin layer chromatography (HPTLC) to search for classes of covalently bound cerebrosides in the SC because this method may provide greater resolution of cerebroside classes. For this procedure we used 10×20 cm plates coated with a 0.20 mm thick layer of silica gel (Si 60,Merck, Darmstadt, Germany). We used the same protocol as for analytical TLC,except that we loaded 3 μl of lipid extract and standards on plates. Plates were developed with chloroform:methanol:water (40:10:1, v/v/v) to the top of the plate and bands of lipid visualized as above.

To quantify the concentrations of the CBL classes, we scanned carbonized plates with a Hewlett Packard scanner, and measured lipid amounts with the software TN Image (Nelson,2003). Validation of our methods indicates that we can routinely measure lipid amounts within ±2%(Muñoz-Garcia and Williams,2005).


Lipids Multiple Choice Questions and Answers

12. Which of the following is a characteristic of both triacylglycerols and glycerophospholipids?

  1. Both contain carboxyl groups and are amphipathic
  2. Both contain fatty acids and are saponifiable.
  3. Both contain glycerol and ether bonds.
  4. Both can be negatively charged at cellular pH.

13. Which of the following is a characteristic of both waxes and terpenes?

  1. Both can contain an amino alcohol.
  2. Both can contain a fatty acid.
  3. Both can be non-saponifiable.
  4. Both can contain oxygen.

14. Which of the following molecules is a typical fatty acid?

  1. A molecule that has an even number of carbon atoms in a branched chain.
  2. An amphipathic dicarboxylic acid with unconjugated double bonds.
  3. A molecule that has one cis double bond in a linear carbon chain.
  4. A polar hydrocarbon with that reacts with NaOH to form a salt.

15. Which property can be shared by this lipid and a terpene?

  1. Both can contain isoprene.
  2. Both can form micelles.
  3. Both can contain a saturated fatty acid.
  4. Both can be very hydrophobic molecules.

16. Which property does this lipid share with a typical triacylglycerol?

  1. Both contain an ether bond.
  2. Both contain a long-chain alcohol.
  3. Both are amphipathic.
  4. Both are saponifiable.

17. Which type of membrane lipid contains an acidic oligosaccharide?

18. Which type of membrane lipid could contain serine?

19. Which will be a characteristic of a steroid that is part of a cell membrane?

  1. It will contain a hydroxyl group.
  2. It will contain four aromatic rings.
  3. It will contain choline.
  4. It will contain an amide bond.

20. Which would be a property of all the major types of lipids in this membrane?


Globo-series carbohydrate antigens are expressed in different forms on human and murine teratocarcinoma-derived cells

The glycolipids of human teratocarcinoma-derived cell line NCCIT were compared with those of 5 murine teratocarcinoma-derived cell lines. Glycolipid antigens were identified by cell surface immunofluorescence and high-performance thin-layer chromatography (HPTLC) immunostaining with a panel of monoclonal anti-carbohydrate antibodies. Human NCCIT embryonal carcinoma (EC) cells contained extended globo-series glycolipids Gb5 (galactosyl globoside) and GL7 (sialyl galactosyl globoside) recognized by antibodies to stage-specific embryonic antigens 3 and 4 (SSEA-3 and -4). SSEA-4 was not detected by immunofluorescence on the surface of any of the 5 murine teratocarcinoma-derived cell lines examined however, SSEA-3 was detected on the surface of murine cell lines resembling primitive endoderm (JC44, NF-PE) and trophectoderm (E6496D). HPTLC analysis revealed a large amount of globoside (Gb4) in these differentiated cells, which may account for their labeling with anti-SSEA-3 antibody. Globo-series glycolipids were also detected in murine EC cells however, differences were noted between the 2 cell lines examined. F9 cells contained primarily Gb4 and Forssman glycolipid, whereas NF-1 cells contained only minor amounts of Gb4 and lacked Forssman glycolipid entirely. Our results, coupled with the known distribution of Forssman antigen in the egg cylinder-stage mouse embryo, suggest that F9 and NF-1 murine EC cells are replicas of cells at different stages of development of the embryonic ectoderm. Glycolipids of normal mouse embryos were examined for comparison. Gb4 and Forssman glycolipid were presents in both embryonic and extra-embryonic tissues, whereas Gb5 and GL7 were restricted to visceral yolk sac and placenta. Our results demonstrate that human and murine teratocarcinoma-derived cells both synthesize extended globo-series glycolipids however, oligosaccharide chain elongation takes different pathways in the 2 species. These differences reflect species-related and cell type-specific patterns of glycosylation.


What are Sphingolipids?

A type of lipids that associate the cell membranes are referred to as sphingolipids. They are based on an eighteen carbon amine alcohol. In simple terms, sphingolipids contain organic aliphatic amino alcohol sphingosine or any substance that resembles the sphingosine. All the members that belong to the group sphingolipids contain a complex or simple sugar that is attached to the first carbon of the alcohol group (C1). The member that deviates from this common structure is sphingomyelin. This molecule consists of a phosphorylcholine group that is the same polar head group present in phosphatidylcholine.

Since sphingomyelin does not contain the sugar moiety, it is considered as an analog to phosphatidylcholine. In addition to the sugar, all sphingolipids contain a fatty acid, which is attached to the amino group of the sphingosine molecule. The sphingomyelin is the only sphingolipid that is considered as a phospholipid that functions as a major component of biological membranes.

Figure 02: Structure of Sphingolipds

The sphingomyelin is the only phosphorous containing sphingolipids that are present in abundant forms in the nervous tissue. Sphingomyelins also present in the blood. Sphingolipidosis and sphingolipodystrophy are two disease conditions that are developed due to abnormal sphingolipid metabolism. Due to the accumulation of sphingolipids in the brain, there can be a development of a rare disease called Tay Sachs disease condition.


Increased cerebroside concentration in plasma and erythrocytes in Gaucher disease: Significant differences between Type I and Type III

A method was developed for the determination of cerebrosides in 1 ml of plasma or 1 ml of packed erythrocytes. At least 90% of the cerebroside fraction consisted of glucosylceramide. In the erythrocytes, nothing but glucosylceramide was identified. The method was applied to plasma samples from 25 controls, 34 Gaucher Type III obligate carriers, 16 Gaucher Type III patients, 7 Gaucher Type I patients and 7 patients with myelogenous or lymphatic leukemia, as well as to erythrocyte samples from 20 controls, 6 Gaucher Type III obligate carriers, 16 Gaucher Type III patients and 6 Gaucher Type I patients. The concentration of plasma cerebroside was 11.4±4.2 (S.D.) in controls, 11.8 ± 2.6 in Gaucher Type III carriers, 30.4 ± 7.7 in Gaucher Type III patients and 21.8 ± 6.7 &mumol/l in Gaucher Type I patients. The Gaucher patients had Significantly increased (p <0.001) plasma cerebroside values, while the plasma cerebroside concentration of the leukemic patients was only slightly increased, 14.7 ± 5.7 &mumol/l. In the packed erythrocyte pellet the corresponding values were: Controls 2.9 ± 0.7, Gaucher Type III carriers 2.9 ± 0.7, Gaucher Type III patients 9.2 ± 2.4 and Gaucher Type I patients 6.5 ± 2.7 &mumol/l. The phospholipid concentration was the same in all the three Gaucher groups and was not significantly different from that in the controls.

Journal

Published: Nov 1, 1982

Keywords: Cerebroside Gaucher disease Type I and III (Norrbottnian Type) glucosylceramide in plasma and erythrocytes heterozygotes leukemia patients splenectomy


5 Important Types of Saponifiable Lipids (With Diagram)

The neutral fats, triglycerides, or triacylglycerols are esters of glycerol and three fatty acids and have the general formula shown in Figure 6-2.

In this for­mula, n, n’, and n” may be the same number or differ­ent numbers.

Usually, the fatty acid that is esterified to the first carbon atom of glycerol (i.e., the top car­bon in Fig. 6-2) is saturated, whereas the fatty acid esterified to the middle carbon atom is unsaturated.

Either saturated or unsaturated fatty acids are found at the third carbon position. Unlike the fatty acids, the neutral fats are entirely non-polar. Neutral fats, which are often deposited in cells as potential sources of chemical energy, represent the major type of stored lipid they occur as droplets in the cytoplasm and most of the lipid that is recovered in the soluble phase or cy­tosol of disrupted cells takes this form. The lipid drop­lets stored in abundance in muscle cells are clearly seen in Figure 6-3.

2. Glycerophosphatides:

The major members of this group of lipids are deriva­tives of phosphatidic acid. Phosphatidic acid is simi­lar to a triglyceride except that one of the fatty acids is replaced by a phosphate group (Fig. 6-4). Phos­phatidic acid and its derivatives are present in plasma membranes, where they play an active role in mem­brane function in addition to serving as major structural constituents (Fig. 6-3).

The most common derivatives of phosphatidic acid are phosphatidyl choline (also known as lecithin), phosphatidyl ethanolamine (also known as cephalin), phosphatidyl serine, and phosphatidyl inositol (Fig. 6-5). Free rotation about the single bonds of the glycerol backbone allows the hydrophilic phosphate and its derivatives to face away from the hydrophobic portion, as shown in the structural formulas of Figure 6-5.

Consequently, glycerophosphatides (and other lipids discussed below) are amphipathic, that is, one end of the molecule is strongly hydrophobic (i.e., the end containing the hydrocarbon chains) while the other end is hydrophilic due to the charged nature of the dissociated phosphate group and other substituent’s. In the presence of water, glycerophosphatides can behave in various ways (Fig. 6-6). For example, they can form monolayers (i.e., monomolecular layers) on the water with their polar ends projecting into the wa­ter and their hydrophobic ends directed away from the water.

Also, like fatty acids, glycerophosphatides can form micelles with the polar ends of the molecules at the micelle’s surface and the hydrocarbon chains pro­jecting toward the center. However, of special signifi­cance is the tendency of glycerophosphatides to form bilayers or bimolecular sheets (Fig. 6-6).

Bilayers formed predominantly from glycerophosphatides are believed to be fundamental to the structure of the plasma membrane, the membranes of the endoplasmic reticulum, and the membranes of vesicular organelles.

Hydrophobic interactions between the tails of the glycerophosphatides are the most important forces promoting the formation of bilayers. The assembly of a bilayer is spontaneous as long as there is adequate lipid present the spontaneous nature of bilayer for­mation is reminiscent of the automatic folding of pro­tein molecules that takes place due to the interaction of hydrophobic amino acid side chains.

When aqueous suspensions of glycero­phosphatides are subjected to rapid agitation using ul­trasound (i.e., insonation), the lipid disperses in the water and forms liposomes or lipid vesicles (Fig. 6- 7). These liposomes consist of a spherical bilayer of the glycerophosphatide molecules enclosing a small vol­ume of the aqueous medium. If small molecules and ions are initially dissolved in the water, some of these will be enclosed by the liposomes.

The ability of differ­ent substances inside or outside the liposomes to tra­verse the bilayer can be studied experimentally. When this is done, it is found that liposomes exhibit many of the permeability properties of natural cellular mem­branes.

In recent years there has been considerable interest in using liposomes as vectors for the transfer of drugs, proteins, nucleic acids, ions, and other molecules into cells. The mechanism is illustrated in Figure 6-8. Li­posomes are either incubated or formed de novo in aqueous solutions of the substance to be transferred and are then washed free of un-encapsulated material. When mixed with cells in vitro or introduced in vivo (e.g., through intravascular or intra-peritoneal injec­tion), the liposomes fuse with the plasma membranes of the target cells.

The contents of the liposome may enter the cell via either of several routes:

(1) Following fusion, the liposome’s contents may be emptied into the cytosol

(2) The entire liposome may be endocytosed and degraded, thereby releasing the entrained substances in the cell and/or

(3) The liposomes may undergo degradation extracellularly, creating a local­ized high concentration of material that may then be incorporated by the cell. The capability to produce li­posomes that differentially bind to the surfaces of spe­cific types of cells and tissues holds great therapeutic promise, for it would make it possible to deliver spe­cific chemical agents to specific tissues.

Plasmalogens are a special class of lipids especially abundant in the membranes of nerve and muscle cells and also characteristic of cancer cells. A plasmalogen is similar to a glycerophosphatide except that the fatty acid at the number 1 position of the glycerol is replaced by unsaturated ether (Fig. 6-9).

Sphingolipids are derivatives of sphingosine, an amino alcohol possessing a long, unsaturated hydro­carbon chain (Fig. 6-10a). The myelin sheath sur­rounding many nerve cells is particularly rich in the sphingolipid sphingomyelin (Fig. 6-10b). In sphingo­myelin, the amino group of the sphingosine skeleton is linked to a fatty acid and the hydroxyl group is esterified to phosphorylcholine.

The outer surface of the plasma membrane of most cells is studded with short chains of sugars. These sugars are either parts of glycoproteins or they are attached to membrane lipids, thereby forming glycolipids. Glycolipids in the plasma mem­brane play vital roles in immunity, blood group speci­ficity, and cell-cell recognition.

The carbohydrates that are found in glycolipids vary from individual mono saccharides (e.g., glucose and galactose) to short, branched or unbranched oligosaccharides. The lipid portion of a glycolipid is similar to sphingosine with the amino group of the sphingosine skeleton acylated by a fatty acid (as in sphingomyelin) and the hy­droxyl group associated with the carbohydrate.

The simplest glycolipids are the cerebrosides, which, as their name suggests, are abundant in brain tissue, where they are found in the myelin sheaths and may account for as much as 20% of the sheath’s dry weight. Small amounts of cerebrosides are also found in kidney, liver, and spleen cells. Usually, the sugar of a cerebroside is either glucose or galactose (Fig. 6- 11).

In the gangliosides (also associated with nerve tissue), the carbohydrate portion of the molecule con­sists of a chain of sugar molecules usually including glucose, galactose, and neuraminic acid. One particu­lar ganglioside, called GM2, may accumulate in the lysosomes of brain cells because of a genetic defi­ciency that result in the failure of the cells to produce a lysosomal enzyme that degrades this ganglioside. The condition is known as Tay-Sachs disease and fre­quently leads to paralysis, blindness, and retarded de­velopment.


A carbohydrate-carbohydrate interaction between galactosylceramide-containing liposomes and cerebroside sulfate-containing liposomes: Dependence on the glycolipid ceramide composition

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Watch the video: Glycolipids structure and types Lecture#9 in English by Dr Hadi (January 2022).