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A Kobata

Publications and source records attributed to A Kobata.

At least 109 records · Page 6Linked to original sources
PubMed1989

Structural study of the carbohydrate moieties of two human immunoglobulin subclasses (IgG2 and IgG4).

Asparagine-linked sugar chains were quantitatively released as oligosaccharides from human IgG2 and IgG4 myeloma proteins by hydrazinolysis followed by N-acetylation and NaB3H4 reduction. Each oligosaccharide was isolated by serial lectin column chromatography. Study of their structures by sequential exoglycosidase digestion and methylation analysis, revealed that all of them were of the bi-antennary complex-type containing Man alpha 1-6(+/- GlcNAc beta 1-4)(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4(+/- Fuc alpha 1-6)GlcNAc as core structures, and GlcNAc beta 1-, Gal beta 1-4GlcNAc beta 1- and Sia alpha 2-6Gal beta 1- in their outer chain moieties. However, the molar ratio of each oligosaccharide was different in each IgG sample, indicating that clonal variation is included in the sugar chain moieties of IgG molecules. One of the IgG2 contained four asparagine-linked sugar chains in one molecule, two on the Fc fragment and the remainder on the Fab fragment. The sugar chains in the Fc fragment contained much less galactose as compared with the Fab fragment.

Asparagine↗
PubMed1989

Structural study of the sugar chains of human platelet thrombospondin.

The asparagine-linked sugar chains of human platelet thrombospondin were released as oligosaccharides by hydrazinolysis. About 12 mol of sugar chains was released from one thrombospondin molecule. This was converted to radioactive oligosaccharides by sodium borotritide reduction after N-acetylation, and separated into one neutral and four acidic fractions by paper electrophoresis. More than 90% of the oligosaccharides were recovered in the acidic fraction. The acidic oligosaccharides were mostly converted to neutral oligosaccharides by sialidase treatment, indicating that they are sialyl derivatives. The neutral and sialidase-treated acidic oligosaccharides were further fractionated by Bio-Gel P-4 column chromatography. Structural study of each oligosaccharide by sequential exoglycosidase digestion and methylation analysis revealed that the thrombospondin contains mono-, bi-, tri-, and tetraantennary complex-type sugar chains in addition to a small amount of high-mannose type. Approximately 70% of the complex-type sugar chains was fucosylated at asparagine-linked N-acetylglucosamine residue and 19% of the biantennary complex-type sugar chains was bisected.

Blood Platelets↗
PubMed1989

Structural studies of the asparagine-linked sugar chains of two immunoglobulin M's purified from a patient with Waldenström's macroglobulinemia.

The structures of the sugar chains present in two human monoclonal IgM molecules purified from the serum of a patient with Waldenström's macroglobulinemia have been determined. The asparagine-linked sugar chains were liberated as oligosaccharides by hydrazinolysis and labeled by reduction with NaB3H4 after N-acetylation. Their structures were studied by serial lectin column chromatography and sequential exoglycosidase digestion in combination with methylation analysis. These two IgM's were shown to contain almost the same sugar chains. The sugar chains were a mixture of a series of high-mannose-type and biantennary complex-type oligosaccharides. The complex-type oligosaccharides contain Man alpha 1----6(+/- GlcNAc beta 1----4)(Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4(Fuc alpha 1----6)GlcNAc as their core and GlcNAc beta 1----, Gal beta 1----4GlcNAc beta 1---- and Neu5Ac alpha 2----6Gal beta 1----4GlcNAc beta 1---- groups in their outer chain moieties.

Asparagine↗
PubMed1989

Relationship between sugar chain structure and biological activity of recombinant human erythropoietin produced in Chinese hamster ovary cells.

Two forms of erythropoietin, EPO-bi and EPO-tetra, with different biological activities were isolated from the culture medium of a recombinant Chinese hamster ovary cell line, B8-300, into which the human erythropoietin gene had been introduced. EPO-bi, an unusual form, showed only one-seventh the in vivo activity and 3 times higher in vitro activity of the previously described recombinant human EPO (standard EPO). In contrast, EPO-tetra showed both in vivo and in vitro activities comparable to those of the standard EPO. EPO-bi, EPO-tetra, and the standard EPO had the same amino acid composition and immunoreactivity. However, structural analyses of their N-linked sugar chains revealed that EPO-bi contains the biantennary complex type as the major sugar chain, while EPO-tetra and the standard EPO contain the tetraantennary complex type as the major sugar chain. From examination of various preparations of recombinant human EPO, we found a positive correlation between the in vivo activity of EPO and the ratio of tetraantennary to biantennary oligosaccharides. These results suggest that higher branching of the N-linked sugar chains is essential for effective expression of in vivo biological activity of EPO.

Animals↗
PubMed1989

Sialic acids, but not their linkage to galactose residues, are required for full expression of the biological activity of human chorionic gonadotropin.

One of the characteristic features of the asparagine-linked sugar chains of human chorionic gonadotropin (hCG) is that their sialic acid residues occur exclusively as the Neu5Ac alpha 2----3Gal group. In order to determine whether this sialic acid linkage is important for the functional role played by the sugar moiety of hCG or not, isomeric hCG containing the Neu5Ac alpha 2----6Gal group was prepared and its hormonal activity in vitro was investigated. On addition of the isomeric hCG to the culture medium of a murine Leydig tumor cell line, it was found that it shows the same hormonal activity as natural hCG.

Adenylyl Cyclases↗
PubMed1989

Comparative study of the sugar chains of gamma-glutamyltranspeptidases purified from human hepatocellular carcinoma and from human liver.

The sugar chains of gamma-glutamyltranspeptidases, purified from human hepatoma and from normal human liver, were released quantitatively as oligosaccharides by hydrazinolysis. Comparative study of their structures revealed that the following structural alterations are induced by hepatocyte carcinogenesis: 1) high mannose type sugar chains are detected in the hepatoma enzyme but not in the normal liver enzyme; 2) abnormal biantennary sugar chains containing C-2,4 outer chain branches newly appeared; 3) the total amounts of tri- and tetraantennary sugar chains containing C-2,6 outer chain branches increased up to three times.

Carbohydrates↗
PubMed1989

Structures of asparagine-linked oligosaccharides of human placental fibronectin.

The asparagine-linked sugar chains of fibronectin purified from human placenta were quantitatively released as oligosaccharides by hydrazinolysis. After N-acetylation, they were converted to radioactive oligosaccharides by NaB3H4 reduction. The radioactive oligosaccharides were fractionated by their charge on an anion-exchange column chromatography. All of the acidic oligosaccharides could be converted to neutral oligosaccharides by sialidase digestion. These oligosaccharides were then fractionated by serial affinity chromatography using immobilized lectin columns. Study of each oligosaccharide by sequential exoglycosidase digestion and methylation analysis revealed the following information as to the structures of the sugar chains of human placental fibronectin: 1) nine sugar chains are included in one molecule; 2) all sialic acid residues are exclusively linked at the C-3 position of the galactose residues; 3) bi-, tri-, and tetraantennary complex-type oligosaccharides with the Man alpha 1----6(Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4 (+/- Fuc alpha 1----6)-GlcNac as their cores were found; 4) the bisecting N-acetylglucosamine residue and the Gal beta 1----4GlcNAc beta 1----repeating groups are included in some of the sugar chains.

Asparagine↗
PubMed1989

Detection of bisected biantennary form in the asparagine-linked oligosaccharides of fibronectin isolated from human term amniotic fluid.

Fibronectin purified from human term amniotic fluid contains 10 asparagine-linked sugar chains in one molecule. The sugar chains were quantitatively liberated as radioactive oligosaccharides from the polypeptide moiety by hydrazinolysis followed by N-acetylation and NaB3H4 reduction and fractionated by anion-exchange column chromatography and serial lectin affinity chromatography. The structures of these sugar chains were determined by sequential exoglycosidase digestion in combination with methylation analysis. The results indicated that they are a mixture of bisected and non-bisected bi- and triantennary complex-type sugar chains with and without a fucose on the proximal N-acetylglucosamine residue and with Gal beta 1----4GlcNAc beta 1----, GlcNAc beta 1----, Neu5Ac alpha 2----3Gal beta 1----4GlcNAc beta 1----, and Neu5Ac alpha 2----6Gal beta 1----4GlcNAc beta 1---- groups in their outer chain moieties.

Amniotic Fluid↗
PubMed1989

Elucidation of the phenotypic change on the surface of Had-1 cell, a mutant cell line of mouse FM3A carcinoma cells selected by resistance to Newcastle disease virus infection.

Had-1, which was isolated from mouse FM3A carcinoma cells, was a non-permissive mutant cell line to Newcastle disease virus infection. Comparative study of the asparagine-linked sugar chains of the surface glycoproteins of the mutant and its parental cells revealed that galactosylation of the complex-type sugar chains is extensively reduced in the mutant. Assay of galactosyltransferase in the two cell lines, however, showed that the enzymatic activity in Had-1 cells is virtually identical to that in FM3A cells. Somatic cell hybridization analysis indicated that the mutant has the same defect as Chinese hamster ovary cell mutant Lec 8, which is deficient in UDP-galactose transport into Golgi vesicles.

Asparagine↗
PubMed1989

Glycoproteins composed of major surface immunodeterminants of Pneumocystis carinii.

Pneumocystis carinii is a pathogen which causes fatal pneumonia in patients with acquired immune deficiency syndrome. To facilitate the basic study of P. carinii, we analyzed the major surface proteins by immunochemical and biochemical methods. The major protein components of both cysts (resting form) and trophozoites (vegetative form) are part of a group of proteins called P115 with apparent masses of 105 to 120 kilodaltons. They represent an unusually large portion of the total proteins of this organism. The purified proteins exhibited six isoelectric variants when analyzed by two-dimensional gel electrophoresis. A monoclonal antibody raised against cysts recognized all six variants and reacted with epitopes that were located in the cell wall, thereby indicating that P115 is an immunoreactive surface component. Data are presented that the isoelectric variants contain identical or closely related protein components and that they are mannose-rich glycoproteins. Deglycosylated P115 migrates primarily as a single more acidic protein in two-dimensional gels, suggesting that the isoelectric variants may be due primarily to differences in glycosylation. The majority of sera tested from humans with diagnosed pneumocystosis reacted strongly with the P115 proteins.

Animals↗
PubMed1989

Effects of galactose depletion from oligosaccharide chains on immunological activities of human IgG.

We previously reported a decrease in the content of galactose residues in oligosaccharide chains of serum IgG from patients with rheumatoid arthritis, which was presumed to affect the 3 dimensional structure of CH2 domain. In the present study, we prepared the galactose depleted IgG (agalacto IgG) and characterized its immunological activities. Significant reduction in Clq binding and Fc receptor binding was observed in agalacto IgG. However, IgM rheumatoid factor binding and protein A binding were the same as with intact IgG. Our results implied the biological function of the carbohydrate moiety of human IgG.

Arthritis, Rheumatoid↗
PubMed1988

Carbohydrate binding specificity of immobilized Allomyrina dichotoma lectin II.

The carbohydrate binding specificity of Allomyrina dichotoma lectin II was investigated by analyzing the behavior of various complex type oligosaccharides and human milk oligosaccharides on an A. dichotoma lectin II-agarose column. Basically, the lectin interacts with the Gal beta 1----4GlcNAc group. Substitution of their terminal galactose residues by Neu5Ac alpha 2----6 will enhance their affinity to the lectin. By contraries, substitution at the C-2 or C-3 position of their terminal galactose with other sugars including sialic acid deprives their affinity to the lectin. With this characteristic, the immobilized lectin column can be used to separate complex type oligosaccharides with the Neu5Ac alpha 2----6Gal beta 1----4GlcNAc group from their isomeric oligosaccharides with the Neu5Ac alpha 2----3Gal beta 1----4GlcNAc group, where Neu5Ac is N-acetylneuraminic acid.

Animals↗
PubMed1988

Comparative study of the asparagine-linked sugar chains of natural human interferon-beta 1 and recombinant human interferon-beta 1 produced by three different mammalian cells.

The asparagine-linked sugar chains of natural interferon-beta 1 secreted from human foreskin fibroblasts by poly I:poly C induction and of three recombinant human interferon-beta 1 produced by Chinese hamster ovary cells, mouse epithelial cells (C127), and human lung adenocarcinoma cells (PC8) were released quantitatively as oligosaccharides by hydrazinolysis followed by N-acetylation. After being reduced with either NaB3H4 or NaB2H4, their structures were comparatively analyzed. More than 80% of the sugar chains of natural interferon-beta 1 occur as biantennary complex-type sugar chains, approximately 10% of which contain N-acetyllactosamine repeating structure in their outer chain moieties. The remainders are 2,4- and 2,6-branched triantennary complex-type sugar chains. The sugar chains of the recombinant interferon-beta 1 derived from Chinese hamster ovary cells were very similar to those of its natural counterpart. In contrast, two other recombinant proteins contain quite different sugar chains. The protein derived from C127 cells contains complex-type sugar chains with the Gal alpha 1----3Gal beta 1----4GlcNAc group in their outer chain moieties. Their sialic acid residues occur solely as the Sia alpha 2----6Gal group, where Sia is sialic acid. In contrast, the sialic acid residues of other interferon-beta 1 occur as the Sia alpha 2----3Gal group only. A part of the sugar chains of the protein derived from PC8 cells contains bisecting N-acetylglucosamine residue in addition to the Gal alpha 1----3Gal beta 1----4GlcNAc group.

Asparagine↗
PubMed1988

Comparative studies of the sugar chains of aminopeptidase N and dipeptidylpeptidase IV purified from rat kidney brush-border membrane.

Asparagine-linked sugar chains of rat kidney aminopeptidase N and dipeptidylpeptidase IV were investigated comparatively. Oligosaccharides released from the two enzymes by hydrazinolysis were fractionated by paper electrophoresis, serial chromatographies on columns of immobilized Aleuria aurantia lectin, concanavalin A, phytohemagglutinin E4, and Datura stramonium agglutinin, and Bio-Gel P-4 (less than 400 mesh) column chromatography. Structures of oligosaccharides in each fraction were assumed by their effective molecular sizes and behaviors on the four lectin columns and then confirmed by sequential exoglycosidase digestion and methylation analysis. The sugar chains of aminopeptidase N and dipeptidylpeptidase IV are almost the same as those of rat kidney gamma-glutamyltranspeptidase reported previously [Yamashita, K., Hitoi, A., Matsuda, Y., Tsuji, A., Katunuma, N., & Kobata, A. (1983) J. Biol. Chem. 258, 1098-1107]. They are a mixture of 5 high mannose type sugar chains and 32 (for aminopeptidase N) or 26 (for dipeptidylpeptidase IV) mono-, bi-, tri-, and tetraantennary complex type sugar chains. The unique feature of the complex-type sugar chains of both enzymes is that they all contain the bisecting N-acetylglucosamine residue and are incompletely galactosylated in their outer-chain moieties.

Aminopeptidases↗
PubMed1988

Comparative study of the asparagine-linked sugar chains of human erythropoietins purified from urine and the culture medium of recombinant Chinese hamster ovary cells.

The asparagine-linked sugar chains of human erythropoietin produced by recombinant Chinese hamster ovary cells and naturally occurring human urinary erythropoietin were liberated by hydrazinolysis and fractionated by paper electrophoresis, lectin affinity chromatography, and Bio-Gel P-4 column chromatography. Both erythropoietins had three asparagine-linked sugar chains in one molecule, all of which were acidic complex type. Structural analysis of them revealed that the sugar chains from both erythropoietins are quite similar except for sialyl linkage. All sugar chains of erythropoietin produced by recombinant Chinese hamster ovary cells contain only the NeuAc alpha 2----3Gal linkage, while those of human urinary erythropoietin contain the NeuAc alpha 2----6Gal linkage together with the NeuAc alpha 2----3Gal linkage. The major sugar chains were of fucosylated tetraantennary complex type with and without N-acetyllactosamine repeating units in their outer chain moieties in common, and small amounts of 2,4- and 2,6-branched triantennary and biantennary sugar chains were detected. This paper proved, for the first time, that recombinant technique can produce glycoprotein hormone whose carbohydrate structures are common to the major sugar chains of the native one.

Animals↗