[Immunochemical studies on blood groups. 38. Structures and activities of oligosaccharides produced by alkaline degradation of blood-group Lewis-a substance. Proposed structure of the carbohydrate chains of human blood-group A, B, H, Le-a, and Le-b substances]

Characterization of three intermediates in the biosynthesis of teichuronic acid of Micrococcus luteus

Teichuronic acid, the Micrococcus luteus cell wall polysaccharide which consists of D-glucose and N-acetyl-D-mannosaminuronic acid, is synthesized in vitro from uridine diphosphate N-acetyl-D-glucosamine, uridine diphosphate N-acetyl-D-mannosaminuronic acid, and uridine diphosphate D-glucose in a series of reactions catalyzed by a particulate enzyme preparation. Several lipid-linked intermediates are formed, of which the first three are called components A, B, and C. The formation of these intermediates is inhibited by tunicamycin. The lipid moiety of the intermediates is approximately 95% undecaprenol and 5% dodecaprenol as determined by mass spectrometry. The oligosaccharide moieties of components B and C are the disaccharide, N-acetyl-D-mannosaminuronyl-(1,3)-N-acetyl-D-glucosamine, and the trisaccharide, N-acetyl-D-mannosaminuronyl-(1,4)-N-acetyl-D-mannosaminuronyl++ +-(1, 3)-N-acetyl-D-glucosamine, respectively, as determined by the complete degradation of the former and partial degradation of the latter by the alkaline beta-elimination reaction. The saccharide and lipid moieties of the intermediates are linked through pyrophosphate. Thus, component A is P1-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate, component B is P1-N-acetyl-D-mannosaminuronyl-(1, 3)-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate, and component C is P1-N-acetyl-D-mannosaminuronyl-(1,4)-N-acetyl-D-mannosaminurony l-(1, 3)-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate.

A review of the immunogenic and immuno-modulatory properties of glycosphingolipids

This review summarizes recent data concerning the immunogenicity and immunomodulatory properties of glycosphingolipids. Many murine monoclonal antibodies that react with glycosphingolipids have been described recently. Most of these antibodies have been elicited by immunization with tumor cells and they may also bind to glycoproteins that contain similar carbohydrate sequences. Immunization with a variety of tissues, murine teratocarcinomas, myeloid leukemia, and carcinomas of the human lung, colon and stomach, has elicited antibodies that react with the sugar sequence Gal beta 1-4[Fuc alpha 1-3]GlcNAc beta 1-3Gal----. The suppression of lymphocyte responses to mitogens and antigens by gangliosides in vitro has led to suggestions that these glycolipids possess immunodulatory properties in vivo. The in vitro studies were performed by incubating mononuclear cells with either dispersions of pure gangliosides or ganglioside-containing liposomes. In vivo gangliosides are found only in cell membranes or in lipoproteins, where they represent a small mole percent of total lipids, and there is little information about the transfer of gangliosides from lipoproteins to cells in vivo. A role for gangliosides as modulators of the immune response is an interesting possibility that is not supported by physiologically relevant data at present.

Differential binding characteristics and applications of DGal beta 1----3DGalNAc specific lectins

The binding properties of Arachis hypogaea (PNA), Bauhinia purpurea alba (BPL), Maclura pomifera ( MPL ) and Sophora japonica (SJL) lectins were studied by quantitative precipitin and precipitin inhibition assays, demonstrating them to be most specific for DGal beta 1---- 3DGalNAc residues. Additionally, each lectin had its own binding characteristic such as different binding activities to DGal beta 1---- 4DGlcNAc or DGal beta 1---- 3DGlcNAc beta 1----linked oligosaccharides, and/or DGalNAc alpha 1----linked to the Ser or Thr of the protein moiety. These differential binding characteristics can be used for investigating fine differences of the carbohydrate structure of the glycoconjugates, especially those having DGal beta 1---- 3DGalNAc residues as terminal non-reducing ends.

Monoclonal antibody reactive with the human epidermal-growth-factor receptor recognizes the blood-group-A antigen

The hybridoma antibody TL5, which precipitates the EGF receptor from the human epidermoid carcinoma cell line A431, has been shown to recognize the blood-group-A carbohydrate structure. This conclusion has been reached from studies of (a) the binding of the antibody to glycoproteins and haemagglutination of erythrocytes with known blood-group-antigen activities and (b) the inhibition of binding of the antibody to a radiolabelled blood-group-A-active glycoprotein by structurally defined oligosaccharides.

Enzymes involved in the biosynthesis of glycoconjugates. A UDP-2-acetamido-2-deoxy-D-glucose: beta-D-galactopyranosyl-(1 leads to 4)-saccharide (1 leads to 3)-2-acetamido-2-deoxy-beta-D- glucopyranosyltransferase in human serum

A 2-acetamido-2-deoxy-beta-D-glucopyranosyltransferase (N-acetylglucosaminyltransferase) that catalyses the transfer of 2-acetamido-2-deoxy-D-glucose from UDP-2-acetamido-2-deoxy-D-glucose to terminal nonreducing beta-D-galactosyl residues in disaccharides, oligosaccharides, glycoproteins, and glycolipids has been detected in human serum. The preferred acceptors are those with beta-D-galactosyl residues linked (1 leads to 4) to the subterminal sugar residue. Activity is greatest when the second sugar residue is 2-acetamido-2-deoxy-D-glucose but beta-D-Galp-(1 leads to 4)-D-Glc and beta-D-Galp-(1 leads to 4)-D-Man are also good acceptors. Compounds with beta-D-galactosyl groups linked (1 leads to 3) to 2-acetamido-2-deoxy-D-glucose are relatively poor acceptors and beta-D-Galp-(1 leads to 6)-D-GlcNAc is inactive. Oligosaccharides substituted with an L-fucose unit on the beta-D-galactosyl unit or on the adjacent sugar residue failed to accept 2-acetamido-2-deoxy-D-glucose. Similarly, glycoproteins with L-fucose or sialic acid substituents are less effective acceptors before removal of these sugars to expose more beta-D-galactosyl end-groups. The transferred 2-acetamido-2-deoxy-beta-D-glucopyranosyl residue is cleaved from the enzymic reaction products by the N-acetyl-beta-D-glucosaminidase from Jack beans. Methylation analysis of the products of 2-acetamido-2-deoxy-D-glucosyl transfer to N-acetyllactosamine [beta-D-Galp-(1 leads to 4)-D-GlcNAc] and lactose [beta-D-Galp-(1 leads to 4)-D-Glc] revealed that the terminal, nonreducing D-galactosyl group in both these acceptors had been 3-O-substituted with 2-acetamido-2-deoxy-D-glucose. Hence, the enzyme in human serum catalyses, in the presence of Mn2+, the reaction UDP-GlcNAc + beta-D-Galp-(1 leads to 4)-R leads to beta-D-GlcpNAc(1 leads to 3)-beta-D-Galp-(1 leads to 4)-R + UDP and is a UDP-2-acetamido-2-deoxy-D-glucose: beta-D-galactopyranosyl-(1 leads to to 3)-2-acetamido-2-deoxy-beta-D-glucopyranosyltransferase.

Characterization of the neutral glycopeptides containing the structure alpha-L-fucopyranosyl-(1 leads to 3)-2-acetamido-2-deoxy-D-glucose from human neuroblastoma cells

Human tumor cells of neurectoderm origin contain a high proportion of alpha-L-fucosyl linkages were determined by high-resolution, 500-MHz, 1H-n.m.r. spectroscopy which gave signals characteristic for alpha-L-Fucp-(1 leads to 3)-D-GlcNAc residues these L-fucosyl residues. This was shown by use of a specific alpha-L-fucosidase from almond emulsin and a broad-spectrum alpha-L-fucosidase from rat testes. The exact alpha-L-fucosyl linkages were determined by high-resolution, 500-MHz, 1H-n.m.r. spectroscopy which gave signals characteristic for alpha-L-Fucp-(1 leads to 3)-D-GlcNAc residues linked to branches and for alpha-L-Fucp-(1 leads to 6)-D-GlcNAc residues linked to the core. More than 95% of the asparagine-linked GlcNAc residues were substituted with (1 leads to 6)-alpha-L-fucosyl groups. Further definition of the range of neutral glycopeptides was obtained with immobilized lectins. Binding to E-PHA-agarose suggested the presence of a beta-D-mannopyranosyl residue substituted at O-4 by a 2-acetamido-2-deoxy-D-glucopyranosyl group. alpha-L-Fucp-(1 leads to 3)-GlcNAc interfered with this binding since removal of alpha-L-fucosyl groups by almond emulsin alpha-L-fucosidase increased the binding by 100%. These studies demonstrate the ability of a combination of high-resolution 1H-n.m.r., enzyme degradation, and lectin-binding affinities to delineate structural elements of small amounts of oligosaccharide residues.

The role of the sugar regions of components of the cytochrome P-450-linked mixed-function oxidase (monooxygenase) system of bovine adrenocortical mitochondria

Cytochrome P-450scc from bovine adrenocortical mitochondria was found to be a glycoprotein, similar to NADPH-adrenodoxin reductase. The role of sugar moieties of components of the cytochrome P-450-linked mixed-function oxidase system was investigated. The NADPH-ferricyanide reductase activity of NADPH-adrenodoxin reductase was not affected by neuraminidase treatment, but NADPH-cytochrome c reductase activity of NADPH-adrenodoxin reductase and adrenodoxin was lost. Cytochrome P-450scc treated with neuraminidase could not be reduced by NADPH-adrenodoxin reductase and adrenodoxin, and the side-chain cleavage activity of cholesterol by the cytochrome P-450-linked mixed-function oxidase system was lost by neuraminidase treatment of cytochrome P-450scc or NADPH-adrenodoxin reductase or both. These results indicate that the sugar moieties of the components of the cytochrome P-450-linked mixed-function oxidase system are necessary for binding and attaching of the components and electron transport.

Immunochemical studies of infectious mononucleosis--X. Characterization of a glycoprotein from horse erythrocytes which reacts with Paul-Bunnell antibody

A highly purified preparation of horse erythrocyte glycoprotein was prepared from an aqueous ethanolic extract of hemoglobin-free membranes. The subunit apparent mol. wt was 30,000. In aqueous solution the glycoprotein formed globular aggregates of 93 +/- 16 A diameter. The glycoprotein had a receptor for the Paul-Bunnell antibody of infectious mononucleosis which was associated with an O-glycosidically linked oligosaccharide and dependent on the presence of N-glycolylneuraminic acid. In addition the glycoprotein had a neuraminidase-sensitive receptor for human peripheral blood lymphocytes. Fifty per cent inhibition of the rosetting of sheep red cells by 4 x 10(5) lymphocytes was caused by 30 microgram of glycoprotein.

Sheep gastric mucins as a source of blood-group-I and -i antigens

Gastric-mucosal glycoproteins of sheep have been shown to express the blood-group-I and -i antigens. The highest blood-group-I activities were found in glycoproteins lacking in blood-group-A and -H activities. In antigenically very active glycoprotein preparations, approx. 25% of the macromolecules expressed various blood-group-I and -i antigens, and these could be enriched by affinity chromatography with an anti-(blood group I) immunoadsorbent column. Additional blood-group-I and -i activities could be revealed by one cycle of Smith degradation of blood-group-A-active sheep gastric glycoproteins. Thus sheep gastric mucins are an abundant source of oligosaccharides with blood-group-I- and -i-active sequences.

Characterization of glycopeptides isolated from membranes of F9 embryonal carcinoma cells

From cells of a nullipotential line of embryonal carcinoma was isolated a membrane fraction enriched in the cell surface F9 antigen. More than 40% of the radioactive fucose and galactose incorporated by cells into nondialyzable material was recovered in this membrane preparation, corresponding to an approximately 10-fold purification of the labeled material. Extreme heterogeneity of membrane glycoproteins labeled with these sugars was revealed by sodium dodecyl sulfate gel electrophoresis. Glycopeptides prepared by extensive pronase digestion of membranes labeled with fucose or galactose showed properties similar to those already described for fucose-labeled glycopeptides from whole cells. Namely, large glycopeptides eluted near the excluded volume of Sephadex G-50 column were the predominant glycopeptide species, while complex glycopeptides of molecular weight around 2500 were minor components. Therefore, these large glycopeptides, characteristic of embryonal carcinoma cells, are derived mainly from a variety of glycoproteins closely associated with the membrane system, most probably cell-surface membrane of the cells. The large glycopeptides were also significantly labeled with glucosamine, but only slightly with mannose; major components of mannose-labeled glycopeptides from the membranes were high-mannose glycopeptides of low molecular weight. Several experiments excluded the possibility that the larg glycopeptides are mucopolysaccharides, glycolipids or mucin-type glycoproteins with short oligosaccharide chains.

Biosynthesis of a blood-group-I determinant reacting with anti-I Ma serum (group 1)

A blood-group-I determinant reacting specifically with anti-I Ma serum (group 1) has been produced biosynthetically by the action of a beta-galactosyl transferase isolated from human milk on a precursor glycoprotein produced by formic acid hydrolysis and beta-D-galactosidase action on blood-group H substance prepared from hog gastric mucosa.

Action of 2-acetamido-2-deoxy-beta-D-hexosidase from Turbo cornutus on periodate-oxidized and Smith-degraded, blood-group HLeb and Lea substances from human, ovarian-cyst fluids

Immunochemical and chemical studies were used to monitor and evaluate the structural changes produced by an enzyme from Turbo cornutus in periodate-oxidized and Smith-degraded, human blood-group substances from ovarian cysts. After the first step of periodate oxidation and Smith degradation, two blood-group substances, JS (HLeb and N-1 (Lea), were precipitated by mouse-myeloma S117 serum, specific for terminal, nonreducing, beta-D-linked 2-acetamido-2-deoxy-D-glucosyl groups, but not by type XIV antipneumococcal horse serum specific for terminal, nonreducing, beta-D-linked D-galactosyl groups. An exoglycosidase, 2-acetamido-2-deoxy-beta-D-hexosidase (beta-N-acetylhexosaminidase) from Turbo cornutus, split off 2-acetamido-2-deoxy-D-glucose amounting to 22.5 and 20.4% of the total weight of JS and N-1 blood-group substances, respectively. After enzymic digestion, both blood-group substances precipitated with type XIV serum, and did not precipitate with S117 serum. The findings are in agreement with the structure propsed for the water-soluble, blood-group substances [Lloyd and Kabat, Proc. Natl. Acad. Sci. U.S.A., 61 (1968) 1477]. Specific enzymes can be of value in structural studies when used in conjunction with sequential periodate oxidation and Smith degradation.

The structure of carbohydrate chains of blood-group substance. Isolation and elucidation of the structure of higher oligosaccharides from blood-group substance H

Twenty individual higher reduced oligosaccharides, having from seven to eleven monosaccharide units, were isolated after sodium borohydride degradation of blood-group substance H from pig stomach linings. Anion-exchange high-pressure liquid chromatography appears to be a very convenient and effective method for this kind of higher oligosaccharide mixtures separation. The oligosaccharide structures were determined by means of periodate oxidation, methylation analysis, partial acid and enzymic hydrolysis. It has been found that all the oligosaccharides investigated can be divided into four series. The oligosaccharides belonging to each series have the common oligosaccharide fragment to which terminal L-fucose and/or N-acetyl-D-glucosamine residues are attached. Comparison of all the oligosaccharide structures, including tri, penta and hexasaccharides described earlier, shows that the lower oligosaccharides represent the structural element of the higher oligosaccharides.

Enzymatic synthesis of blood-group Lewis-specific glycolipids

A blood-group Lewis precursor glycolipid was isolated from the plasma of a Lewis-negative individual [Le(a--b--)] and treated with fucosyltransferases from human gastric mucosa and GDP-fucose. Subsequently the glycolipid was adsorbed onto Le(a--b--) erythrocytes and the presence of blood-group Lewis antigens was assessed by passive hemagglutination with anti-Lewis sera. It was shown that the precursor glycolipid was enzymatically transformed to blood-group Lewis a (Lea) and Lewis b (Leb) specific glycolipids. Leb-glycolipid was also synthesized by fucosylation of an isolated Lea-glycolipid. Moreover Le(a--b--) erythrocytes were shown to develop Lea and Leb activities when subjected to enzymatic fucosylation, thus showing that Lewis-negative cells carry blood-group Lewis precursor glycolipid on the surface of their membrane. Le(a + b--) erthrocytes, upon enzymatic fucosylation, acquired Leb activity.