Occurrence of ungulic acid in some epidermal tissues

The lipids isolated from different animal tissues have been studied qualitatively, by TLC, for the occurrence of the ungulic acid fraction. This fraction was found in considerable amounts only in epidermal tissues and its keratinized derivatives. In the present study it was isolated from human keratinous epidermis, hair, and nails, pig bristles, wool, and feathers. The analytical results indicated that a lipid fraction from all of these sources contained ceramide, galactose, galactosamine, sulfate, and sialic acid in equimolar amounts, and that the fractions were similar to the ungulic acid isolated earlier from a horse's hoof.     

Sialoglycopeptides isolated from bovine aorta.

Intima-media of bovine aorta was digested with pronase, after preliminary extraction of saline (1%)-soluble substances and fat. Crude glycopeptide fraction was then obtained from the resulting complex carbohydrate fraction by fractionation with CPC (cetylpyridinium chloride). Complete separation of sialoglycopeptides was achieved by chromatography on a DEAE-cellulose column at pH 7.2 followed by repeated chromatography on a DEAE-Sephadex A-25 column at pH 5.2. Nine sialoglycopeptides (SGP 1-SGP 9) thus obtained were homogeneous on high-voltage paper electrophoresis at pH 3.5 and pH 5.2. The analytical data showed great heterogeneity of the carbohydrate chains of these preparations, although they consisted of the same monosaccharides (galactose, glucose, mannose, glucosamine, galactosamine, fucose, and sialic acid), except that SGP 1 lacked galactosamine. Heterogeneity was also observed in their peptide chains. It was noticed, however, that the contents of hexose, hexosamine, and aspartic acid of the fractions (SGP 3, SGP 4, and SGP 5) which eluted from the DEAE-Sephadex A-25 column at lower molarity of the eluting salt were higher than those of the fractions (SGP 7, SGP 8, and SGP 9) which eluted at higher molarity, while the contents of sialic acid and hydroxyamino acids were in an opposite relationship. Representative fractions (SGP 7 and SGP 9) of the latter contained many more alkali-sensitive linkages than those (SGP 3 and SGP 5) of the former, indicating the presence of many more O-glycosidic linkages between hydroxyamino acid(s) and sugar(s) in the latter than in the former. The sialoglycopeptides contained significant amounts of sialic acid, ranging from 10% (sgp 1) to 32.4% (SGP 8). The highest contents were in SGP 8 and SGP 9, which contained equimolar amounts of sialic acid and hexosamine. Furthermore, infrared spectra indicated the presence of sulfate groups in most of the sialoglycopeptides.     

The isolation and characterization of glycopeptides and mucopolysaccharides from plasma membranes of an ascites hepatoma, AH 130 FN.

Plasma membranes were isolated from an ascites hepatoma, AH 130 FN, a free-cell type subline of AH 130, by the fluorescein mercuric acetate (FMA) method. Glycopeptides and mucopolysaccharides were prepared from the membranes by pronase digestion then fractionated chromatographically and electrophoretically. Isolated fractions were analyzed for amino acid and carbohydrate compositions. The results were compared with those for corresponding fractions from AH 66 and AH 130 ((1974) J. Biochem. 76, 319-333; (1975) ibid., 78, 863-872). The fraction excluded from Sephadex G-50 contained mucopolysaccharides and a series of glycopeptides. The mucopolysaccharides were identified as chondroitin sulfate A on the basis of their chemical composition, electrophoretic behavior on cellulose acetate and digestibility with chondroitinase AC [EC 4.2.2.5]. This contrasts with previous findings that mucopolysaccharides from the corresponding fractions from AH 130 and AH 66 were heparan sulfate. The chemical composition of the glycopeptides, which showed high contents of threonine, serine, galactose, galactosamine, glucosamine, and sialic acid, indicated the presence of glycopeptides with O-glycosidic linkages. The glycopeptides also contained a small but significant amount of aspartic acid, suggesting that N-glycosidic glycopeptides were also contained in this fraction. The fraction included in Sepnadex G-50 contaoned N-glycosidic glycopeptides as major components, since the carbohydrate moieties were composed of fucose, galactose, mannose, glucosamine, sialic acid, and a smaller amount of galactosamine. The presence of galactosamine suggested that O-glycosidic glycopeptides were present as minor components. Glycopeptides with both O- and N-glycosidic linkages were isolated from AH 130, but not from AH 66.     

Glycoconjugates secreted by bovine tracheal serous cells in culture

Glycoconjugates secreted by bovine tracheal gland serous cells in culture were characterized after incorporation of radioactive precursor [1-14C]glucosamine and stimulation with isoproterenol. Under dissociative conditions, glycoconjugates eluted in both the void and included volumes on Sepharose Cl-4B. Fractionated by anion-exchange chromatography, the high-molecular-weight (Sepharose Cl-4B; V0) glycoconjugates gave two acidic fractions eluting at 0.5 and 2.0 M NaCl; low-molecular-weight glycoconjugates of the included volumes gave a neutral fraction and two acidic fractions eluting at 0.5 and 2.0 M NaCl. Based on chemical analysis and specific enzymatic digestions, the material eluting in the void volume was shown to contain hyaluronic acid and chondroitin sulfate proteoglycan. In addition, the presence of small amounts of galactose, fucose, sialic acid, glucosamine, and galactosamine suggest the presence of O-glycosidically linked glycoproteins in the void volume. The identification of galactosaminitol in beta-eliminated oligosaccharides from this material confirms this notion. The material eluting in the included volume was shown to contain N-linked glycoproteins with glycans of complex type in the neutral fraction and chondroitin sulfate proteoglycans in the two acidic fractions. Significant N-sulfation of amino sugars was detected in the 0.5 M acidic fraction, indicating the presence of heparan sulfate. Hyaluronic acid and chondroitin sulfate proteoglycan have recently been identified in tracheal secretions; our results suggest that these components originate at least in part from tracheal gland serous cells.     

Characterization of mucin isolated from rat tracheal transplants

Subcutaneous rat tracheal grafts yield several milligrams of secretions from which a homogeneous mucin fraction was isolated and purified. Histological evidence demonstrated that a normal mucociliary epithelium and mucous secretion were maintained for the 4-6 weeks of the experiment. The collected secretions were initially characterized by column chromatography on Sepharose CL-6B which separated the excluded high molecular weight mucins (unpurified mucin fraction) from most of the serum-type glycoproteins and proteins, including albumin. A reductive alkylation treatment of the unpurified mucin fraction followed by Sepharose CL-4B chromatography removed contaminating protein and most of the mannose-containing material from the mucin fraction. The void volume material from this column produced a single high molecular weight band upon sodium dodecyl sulfate agarose/acrylamide gel electrophoresis. The purified mucin fraction contained 16.5% protein and primarily galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid. This fraction also underwent beta-elimination in the presence of alkaline borohydride, demonstrating the presence of O-glycosidic linkages.     

Epithelial basement membrane of bovine renal tubuli. Isolation and analysis of the carbohydrate chains.

The carbohydrate chains present in the tubular basement membrane of bovine kidney were studied. Digestion with collagenase followed with pronase resulted in a complete solubilization of the basement membrane. The different glycopeptides were purified by gel filtration and ion-exchange chromatography. Two kinds of carbohydrate chains could be characterized: oligosaccharides composed of glucosamine, mannose, galactose, fucose and sialic acid, and glucosylgalactose disaccharides. A very small portion of the oligosaccharide chains (ca. 4%) appeared to be free of sialic acid. The bulk of these chains contained sialic acid and fucose, although in small amounts. Only traces of galactosamine were found.     

The isolation and characterization of glycopeptides and mucopolysaccharides from plasma membranes of an ascites hepatoma, AH 130.

Plasma membranes were isolated from an ascites hepatoma, AH 130, by the fluorescein mercuric acetate (FMA) method. Glycopeptides and mucopolysaccharides were prepared by digesting the membranes with pronase, then by fractionating the digest chromatographically and electrophoretically. Isolated fractions were analyzed for their amino acid and carbohydrate compositions. Results were compared with those for corresponding fractions from AH 66 (J. Biochem. 76, 319-333 (1974)). Mucopolysaccharides and a series of glycopeptides were isolated from the fraction excluded from Sephadex G-50. The mucopolysaccharides were identified as a family of heparan sulfates with different electrophoretic mobilities. The glycopeptides contained serine, threonine, galactose, galactosamine, glucosamine, and sialic acid as the major constituents as aspartic acid and mannose as minor ones. This suggests that most of the carbohydrate moieties are linked to serine or threonine (O-glycosidic), and that some are linked to asparagine (N-glycosidic). No nearly purely O-glycosidic glycopeptides were found in this fraction from AH 130, through they were the major glycopeptides from the AH 66 plasma membranes. In the fraction included in the gel, glycopeptides containing fucose, galactose, mannose, glucosamine, glaactosamine, and sialic acid were found. The presence of galactosamine suggests that some of the glycopeptides are O-glycosidic though most are N-glycosidic. In the corresponding fraction from AH 66, nearly purely N-glycosidic glycopeptides were found.     

The carbohydrate components of hydrolysates of gastric secretion and extracts from mucous glands of the gastric body mucosa and antrum

1. The sugars and amino sugars of hydrolysates of gastric secretion were determined by gas-liquid chromatography. 2. All the gastric aspirations examined showed on hydrolysis the presence of fucose, galactose, mannose, glucose, galactosamine, glucosamine, N-acetylneuraminic acid and sulphate. 3. Galactose and glucosamine were always found in equimolar amounts, but the galactose/galactosamine ratio in different aspirations was 2:1, 3:1, 4:1 or 5:1. Repeated gastric aspirations of each subject examined showed constant ratios of these carbohydrate components. 4. Fucose and sialic acid appear to be related to glucosamine and galactosamine respectively. 5. The carbohydrate components of extracts from the mucous glands of the body mucosa and antrum did not differ from those of gastric secretion.     

Studies on thyroid cell surface glycoproteins: Isolation of plasma membranes and characterization of carbohydrate units

Plasma membranes were isolated from calf thyroid microsomes and further resolved into two subfractions by sucrose density gradient centrifugations. The lighter and major membrane fraction was obtained in a yield of 10 mg/100 g of thyroid and was enriched 38-fold with respect to 5′-nucleotidase activity compared to the homogenate. It differed from the denser plasma membrane fraction in containing greater amounts of phospholipid and cholesterol but had a similar total carbohydrate content (16 mg/100 mg protein) and monosaccharide composition. The membranes were found to retain most (80%) of their carbohydrate after delipidation. The major protein-bound sugars present in the lighter membrane fraction expressed as micromoles per 100 mg of peptide were: galactose 24, mannose 17, fucose 3, glucosamine 23, galactosamine 4, and sialic acid 9. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate of the lipid-free membranes revealed at least 18 protein bands and 3 periodic acid-Schiffreactive glycoprotein components. Incubation of the delipidated membranes with Pronase resulted in the solubilization of 95% of the saccharide portion which upon filtration through Bio-Gel P-6 and P-10 columns yielded several glycopeptide fractions. While some of the carbohydrate was found in glycopeptides which appeared to contain the well-known complex and polymannose asparagine-bound oligosaccharides, as well as small O-glycosidically linked units, approximately half was recovered in high molecular weight components which contained galactose and glucosamine as their principal sugar constituents, and which were similar in composition to glycopeptides recently isolated (T. Krusius, J. Finne, and H. Rauvala, 1978, Eur. J. Biochem.92, 289–300) from human erythrocyte membranes.     

Isolation and characterization of a glycoprotein from human colostrum

A glycoprotein was isolated from the M-1 acid glycoprotein fraction of human colostrum. It had a molecular weight of 31200 and contained 27% galactose, 21.7% hexosamine, 8.0% fucose and 10.8% sialic acid by weight. The glycoprotein had no absorption maxima in the 240-300nm region, and was virtually free of ABH(O) and M and N blood-group activity. Alkaline borohydride cleavage of the glycoprotein resulted predominantly in the destruction of threonine and galactosamine.     

Delta 6-desaturase activity in liver microsomes of rats fed diets enriched with cholesterol and/or omega 3 fatty acids.

A glycoprotein antigen was purified from human brain by immunoaffinity chromatography using the 44D10-monoclonal IgG, and its chemical nature was investigated. The yield of antigen was estimated at 91% and a 4340-fold purification was obtained relative to the white-matter homogenate. The antigen preparation from brain was further purified by preparative SDS/polyacrylamide-gel electrophoresis (PAGE) to obtain a glycoprotein with an Mr of 80,000 consisting of a single polypeptide. Amino acid analyses revealed a composition which was high in acidic and neutral amino acids, and low in basic residues. The presence of both glucosamine and galactosamine suggested that the glycoprotein contained both N- and O-linked glycans. Neutral sugar analyses showed that fucose, galactose and mannose were present. An assay for sialic acid determined that there were approximately 20 mol of sialic acid per mol of glycoprotein. Chemical cleavage of oligosaccharides by trifluoromethanesulphonic acid followed by SDS/PAGE showed that carbohydrate accounted for 25,000 of the 80,000-Mr glycoprotein.     

Identification of the milk fat globule membrane proteins: I. Isolation and partial characterization of glycoprotein B

The salt soluble proteins from the fat globule membrane of cow's milk were resolved into three fractions by Sephadex column chromatography in sodium dodecyl sulfate. One of the fractions, termed glycoprotein B, was purified by rechromatography to essentially one band on sodium dodecyl sulfate gel electrophoresis. It was found to contain 14% carbohydrate including sialic acid, mannose, galactose, glucose, glucosamine and galactosamine. The amino acid composition of glycoprotein B was determined; it has amino terminal serine and carboxyl terminal leucine. The molecular weight of this glycoprotein as estimated by sodium dodecyl sulfate gel electrophoresis is 49 500.     

Characterization of mucin isolated from rat tracheal transplants

Subcutaneous rat tracheal grafts yield several milligrams of secretions from which a homogeneous mucin fraction was isolated and purified. Histological evidence demonstrated that a normal mucociliary epithelium and mucous secretion were maintained for the 4–6 weeks of the experiment. The collected secretions were initially characterized by column chromatography on Sepharose CL-6B which separated the excluded high molecular weight mucins (unpurified mucin fraction) from most of the serum-type glycoproteins and proteins, including albumin. A reductive alkylation treatment of the unpurified mucin fraction followed by Sepharose CL-4B chromatography removed contaminating protein and most of the mannose-containing material from the mucin fraction. The void volume material from this column produced a single high molecular weight band upon sodium dodecyl sulfate agarose/acrylamide gel electrophoresis. The purified mucin fraction contained 16.5% protein and primarily galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid. This fraction also underwent β-elimination in the presence of alkaline borohydride, demonstrating the presence of O-glycosidic linkages.     

Nature of the Carbohydrate Side Chains and Their Linkage to the Protein in Chicken Egg White Ovomucin

Some proteolytic digests of chicken egg white ovomucin were fractionated and characterized. It was shown that there are at least three types of carbohydrate side chains in ovomucin; a chain composed of galactose, galactosamine, sialic acid and sulfate in a molar ratio of about 1: 1: 1: 1, a chain composed of galactose and glucosamine in a molar ratio of about 1:1, and a chain composed of mannose and glucosamine in a molar ratio of about 1:1. It was also shown that the carbohydrate side chain composed of galactose, galactosamine, sialic acid and sulfate is linked O-glycosidically to serine or threonine in the protein core of ovomucin.     

Carbohydrate composition of lymphocyte plasma membrane from pig mesenteric lymph node.

Pig lymphocyte plasma membrane isolated from mesenteric lymph node contained 69 mug of carbohydrate/mg dry wt., which was made up of neutral sugar, amino sugar and sialic acid in the molar proportions 5:1.7:1. The neutral sugar comprised fucose, ribose, mannose, glucose, galactose and inositol (molar proportions 2:9:11:15:26:1), and the amino sugar glucosamine and galactosamine (molar ratio 2:1). The ribose was most probably derived from RNA. All of the fucose and mannose and almost all of the glucosamine were associated with the membrane protein whereas the membrane lipid contained all of the inositol. The remaining sugars were distributed in various ratios between the protein and lipid fractions.     

Blood-group ABH-specific macroglycolipids of human erythrocytes: isolation in high yield from a crude membrane glycoprotein fraction

Highly glycosylated, water-soluble ABH-specific sphingolipids, designated macroglycolipids, were isolated in high yield, up to 5 mg per unit of blood, from the crude human-erythrocyte-membrane glycoprotein fraction which is obtained by extraction of the membranes with chloroform/methanol/water. Both serological tests and radioactive labelling experiments indicated that these substances, rather than the glycoproteins, are the principal ABH-components in this fraction. The activities of A-specific, B-specific and H-specific macroglycolipids were very high, approximately 0.1 microgram inhibiting four hemagglutinating doses of the respective agglutinating reagents, and were thus comparable to those of secreted blood-group ABH-specific glycoproteins. The substances were stable to mild alkaline conditions. They contained fucose, galactose, glucosamine, glucose, sialic acid, sphingosine and fatty acids; blood-group-A-specific substances contained, in addition, galactosamine. No amino acids were detected. Assuming one glycosyl residue per molecule, the average number of sugars in A and B macroglycolipids was 31, and their molecular weights approximately 6100. The presence of beta-D-galactosidase-labile and sialic acid residues indicated that these substances contain nonreducing termini additional to the ABH immunodeterminants. In the B macroglycolipid, the ratio between nonreducing terminal alpha-D-galactopyranosyl and beta-D-galactopyranosyl residues was 1.7:1.0. The macroglycolipids formed clear aqueous solutions at concentrations as high as 30 mg/ml, were insoluble in 60--70% aqueous ethanol, and did not migrate on thin-layer chromatography unless they were acetylated. Polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate showed the macroglycolipids to be a heterogeneous mixture migrating throughout most of the region in which the periodic acid/Schiff-positive membrane glycoproteins are found. On the basis of the evidence presented, it is concluded that macroglycolipids are the predominant ABH-specific component in human erythrocyte membranes, and that they most likely account for previous observations of ABH activity in membrane glycoprotein fractions.     

Isolation and characterization of band 3, the predominant polypeptide of the human erythrocyte membrane.

Band 3 is the predominant approximately 90,000-dalton polypeptide component of the human erythrocyte membrane. It was solubilized selectively, along with the other major glycoproteins, by extracting membrane ghosts with Triton X-100 under nondenaturing conditions. Two major polypeptides remained associated with Band 3 under these conditions; however one (Band 6) could be dissociated at an ionic strength of 0.15 and the other (Band 4.2) by treatment with p-chloromercuribenzoate. Band 3 was then purified (greater than or equal to 97%) by aminoethyl cellulose ion exchange chromatography. The isolated protein was free of phospholipid and was moderately enriched in apolar amino acid residues; it contained galactose and glucosamine but very little sialic acid and galactosamine. When Band 3 was labeled by treatment of ghosts with galactose oxidase plus KB3H4 and then purified, the electrophoretic mobility of its radioactivity lagged slightly behing that of its Coomassie blue staining profile. Variation in glycosylation could therefore cause the diffuse trailing zone characteristically observed for Band 3 on polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The ultraviolet circular dichroism of Band 3 was stable in nonionic detergent and suggested an alpha helix content of 43%, a value close to that estimated for this polypeptide in the membrane.     

Studies on the chemical composition of lipopolysaccharide from Neisseria meningitidis group B.

A lipopolysaccharide was isolated from Neisseria meningitidis group B by phenol/water extraction and purified by differential ultracentrifugation. This preparation exhibited endotoxic properties as shown by the limulus-lysate assay. Mild acid hydrolysis of the lipopolysaccharides yielded a lipid A fraction and a polysaccharide fraction. The lipid A fraction contained fatty acids, phosphorus and glucosamine. Analysis of the polysaccharide fraction revealed the presence of glucose, galactose, glucosamine, 2-keto-3-deoxyoctonic acid and phosphorus. There was no heptose.     

Carbohydrate Composition of Vesicular Stomatitis Virus

Analysis by gas-liquid chromatography of the trimethylsilylated sugar residues of purified vesicular stomatitis virus grown in L cells or chick embryo cells revealed the presence in the whole virion of four hexoses (glucose, galactose, mannose, and fucose), two hexosamines (glucosamine and galactosamine), and 34 to 40% neuraminic acid. The isolated viral glycoprotein was devoid of galactosamine and fucose, both of which sugars were present in whole virions presumably as part of the membrane glycolipids.     

The carbohydrate components of arterial basement-membrane-like material. Studies on rabbit aortic myomedial cells in culture.

The carbohydrate composition of arterial basement-membrane-like material was investigated. Basement-membrane-like material was isolated from cultures of aortic myomedial cells by a sonication/differential-centrifugation technique. Purified basement-membrane-like material contained a total of 5% sugars, comprising glucose, galactose, mannose, fucose, sialic acid, glucosamine and galactosamine in the approximate molar proportions 3.2:3.5:3.4:3.2:1:5.5:3.1. In addition, small amounts of xylose were found. Analyses for uronic acid showed that glycosaminoglycans comprised about 1% of isolated basement-membrane-like material. The carbohydrate composition indicated the presence of complex-type oligosaccharides in addition to hydroxylysine-linked disaccharides. [3H]Glucosamine-labelled glycopeptides obtained by proteinase digestion and gel filtration were resistant to endo-beta-N-acetylglucosaminidase D, but more than 10% were susceptible to alpha-mannosidase, demonstrating the presence of high-mannose-type oligosaccharides. The distribution of carbohydrates among peptides of basement-membrane-like material on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis was investigated after labelling with [3H]mannose, [3H]fucose, [3H]galactose and [3H]glucosamine. Among peptides that appeared to carry carbohydrates were a proteoglycan(s) and seven glycoproteins in the molecular-weight range 120 000-700 000.