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Träfflista för sökning "L773:0021 9258 srt2:(1980-1984)"

Sökning: L773:0021 9258 > (1980-1984)

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1.
  • Grubb, A O, et al. (författare)
  • Isolation of human complex-forming glycoprotein, heterogeneous in charge (protein HC), and its IgA complex from plasma. Physiochemical and immunochemical properties, normal plasma concentration
  • 1983
  • Ingår i: The Journal of biological chemistry. - 0021-9258. ; 258:23, s. 707-14698
  • Tidskriftsartikel (refereegranskat)abstract
    • Human complex-forming glycoprotein, heterogeneous in charge (protein HC) has previously been isolated from urine and immunochemically shown to be present in low and high molecular weight forms in blood plasma (Tejler, L., and Grubb, A. O. (1976) Biochim. Biophys. Acta 439, 82-94). In the present work, the major low and high molecular weight forms of the protein were isolated from plasma by immunosorption followed by gel chromatography. The plasma low molecular weight protein HC and the urinary protein had similar, if not identical, molecular weight, amino acid composition, NH2-terminal and carboxyl-terminal amino acid sequences and electrophoretic mobility. The low molecular weight plasma protein HC carried a yellow chromophore like the urinary protein, but its molar extinction coefficient at 280 nm was lower and its charge heterogeneity less pronounced than that of urinary protein HC. The plasma high molecular weight protein HC had a hydrodynamic volume which was greater than that of monomeric IgA but smaller than that of dimeric IgA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the isolated high molecular weight protein followed by electrophoretic blotting and immunochemical analysis demonstrated that the protein contained four polypeptide chains: two light immunoglobulin chains (Mr = 23,000), one IgA alpha-chain (Mr = 54,000), and one chain with Mr approximately 90,000 which carried both alpha-chain and protein HC antigenic determinants. Whether the protein HC X IgA complex is a functionally significant part of the humoral immune system cannot be decided without further experimentation, but the complex was found to be completely absent from the blood plasma of patients with a selective deficiency of IgA-secreting immunocytes. The isolated low and high molecular weight plasma protein HC components were used as standard proteins in the construction of a quantitative crossed immunoelectrophoretic assay for the simultaneous quantitation of the two major protein HC components in blood plasma. The plasma concentrations of the low and high molecular weight protein HC components were measured by this method in 13 healthy Caucasians. The results for the low molecular weight protein HC were: mean, 20.3 mg/liter, S.D., 3.2 mg/liter, range, 13.6-26.0 mg/liter; and for the protein HC X IgA complex: mean, 293 mg/liter, S.D., 176 mg/liter, range, 36-620 mg/liter.
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4.
  • Breimer, Michael, 1951, et al. (författare)
  • Glycosphingolipids of rat tissues. Different composition of epithelial and nonepithelial cells of small intestine.
  • 1982
  • Ingår i: The Journal of biological chemistry. - 0021-9258. ; 257:1, s. 557-68
  • Tidskriftsartikel (refereegranskat)abstract
    • The epithelial cells of rat small intestine (jejunum-ileum) were separated from their supporting stroma (residue). Total nonacid and acid glycosphingolipids were prepared from the two compartments. The acetylated nonacid glycolipids were separated into 10-12 fractions by column chromatography. These were analyzed by chromatographic methods, mass spectrometry, and proton NMR spectroscopy and compared with glycolipids isolated from whole rat small intestine. The sialic acid-containing glycosphingolipids were compared in the same way without subfractionation. At least 37 different glycosphingolipids (different carbohydrate moieties) were found, 23 in the nonepithelial residue and 17 in the epithelial cells of one rat strain. In a second rat strain, another 4 structures were detected. The glycosphingolipids of epithelial cells and nonepithelial residue were distinctly different. Glucosylceramide, lactosylceramide, and globotriaosylceramide were found in both compartments, while isoglobotriaosylceramide was restricted to the nonepithelial residue. A tetrahexosylceramide with a terminal Gal alpha 1 leads to 3 on a globotriaosylceramide core was found in both compartments as were homologues with 1 or 2 additional internal leads to 3Gal alpha 1 leads to units, but homologues with 3 or 4 additional internal Gal were only nonepithelial. Glycosphingolipids with terminal beta-GalNAc were restricted to the nonepithelial residue comprising globotetraosylceramide, isoglobotetraosylceramide, and a series of glycolipids with 5 to 9 sugars having the above-mentioned oligohexosylceramides as core structures. Fucolipids (blood group H) having 3, 5, 6, and 7 sugars and lacking amino sugars, and fucolipids with 5 and 10 sugars containing N-acetylglucosamine were restricted to the epithelial cells. Fucolipids (blood groups H and B) with 5 and 6 sugars containing N-acetylgalactosamine were restricted to the nonepithelial residue. In a 4, 6, and 12 sugars were found in the epithelial cells. N-Glycoloylneuraminosyllactosylceramide was the only ganglioside found in the epithelial cells while N-acetylneuraminosyllactosylceramide was nonepithelial together with gangliosides based on gangliotetraosylceramide and isoglobotetraosylceramide.
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5.
  • Breimer, Michael, 1951, et al. (författare)
  • Isolation and partial characterization of blood group A and H active glycosphingolipids of rat small intestine.
  • 1982
  • Ingår i: The Journal of biological chemistry. - 0021-9258. ; 257:2, s. 906-12
  • Tidskriftsartikel (refereegranskat)abstract
    • Blood group A and H active glycosphingolipids have been isolated from rat small intestine. By mass spectrometry of the permethylated and LiAlH4-reduced permethylated glycolipid derivatives, the A glycolipids were shown to contain four (A-4), six (A-6), and 12 (A-12) sugar residues, respectively. The anomeric structure of the A-4 and A-6 glycolipids was established by proton NMR spectroscopy of the permethylated-reduced derivatives. Acid degradation and gas chromatography were used for analysis of binding positions. The structures of the A-4 and A-6 glycolipids were GalNAcp alpha 1 leads to 3Galp(2 comes from 1Fucp alpha) beta 1 leads to Glcp beta 1 leads to 1Cer and GalNAcp alpha 1 leads to 3Galp(2 comes from 1Fucp alpha) beta 1 leads to 3GlcNAcp beta 1 leads to 4Galp beta 1 leads to 4Glcp beta 1 leads to 1Cer. The third glycolipid (A-12) was a branched dodecaglycosylceramide with two blood group A determinants. The complete structure of this glycolipid has not yet been solved. The blood group A activity was the same for the A-6 and A-12 glycolipids based on an equal number of blood group A determinants, but the activity of the A-4 compound was only about half of the others. The A-6 glycolipid was based on a type 1 (Gal beta 1 leads to 3GlcNAc) carbohydrate chain, thus differing from the already known isomer based on a type 2 chain (Gal beta 1 leads to 4GlcNAc) present in human erythrocyte. The blood group A activity of these two glycolipids was found to be identical. The three rat intestinal blood group A active glycolipids were exclusively located to the mucosa epithelial cells. The blood group H active tri- and pentaglycosylceramides (H-3 and H-5), presumed to be the precursors of the A-4 and A-6 glycolipids, were also identified. A 10-sugar glycolipid (H-10), a possible precursor of A-12, was not detected.
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6.
  • Breimer, Michael, 1951, et al. (författare)
  • Structural identification of two ten-sugar branched chain glycosphingolipids of blood group H type present in epithelial cells of rat small intestine.
  • 1982
  • Ingår i: The Journal of biological chemistry. - 0021-9258. ; 257:1, s. 50-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Two novel blood group H-type decaglycosylceramides with a branched core saccharide have been identified in mixture in a fraction isolated from rat small intestine. They were present exclusively in the epithelial cells. The number and sequence of sugars were established by direct inlet mass spectrometry of the permethylated and LiAlH4-reduced permethylated derivatives. Gas-liquid chromatography of the products after degradation of the native and permethylated glycolipids gave the type of sugars and the binding positions. A di- and a trisaccharide were identified by mass spectrometry after degradation of the permethylated-reduced derivative. One trisaccharide had the structure (formula see text) and was therefore additional evidence for a branched structure. Treatment of the decaglycosylceramide fraction with alpha-L-fucosidase gave free fucose and an octaglycosylceramide identified by mass spectrometry. Proton NMR spectra of the permethylated and permethylated-reduced octa- and decaglycosylceramides provided evidence for the binding configurations and the localization of type 1 and type 2 sequences in the two branches. The 3-linked branch was homogeneous with a type 1 saccharide (Gal beta 1 leads to 3GlcNAc) but the 6-linked branch had both type 1 and type 2 (Gal beta 1 leads to 4GlcNAc) sequences. Two glycolipids with the following probable structures were therefore present, making up 60 and 40% of the mixture, respectively: (formula see text) The lipophilic part contained mainly trihydroxy 18:0 long chain base (phytosphingosine) and 16:0 to 24:0 nonhydroxy fatty acids.
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7.
  • de Luca, S., et al. (författare)
  • Proteoglycans from chick limb bud chondrocyte cultures. Keratan sulfate and oligosaccharides which contain mannose and sialic acid
  • 1980
  • Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 255:13, s. 6077-6083
  • Tidskriftsartikel (refereegranskat)abstract
    • The precursors, [ 35S]sulfate and [2- 3H]mannose, were used to study the biosynthesis of keratan sulfate and other oligosaccharides on proteoglycans isolated from Day 8 cultures of chick limb bud chondrocytes. After alkaline borohydride treatment, three fractions with sialic acid were separated by molecular sieve chromatography. The first contained keratan sulfate which was purified by digestion with chondroitinase to remove chondroitin sulfate, followed by molecular sieve and ion exchange chromatography. The purified keratan sulfate contained about 8% of the 35S activity originally in monomer. The chains had an average length of about 40 monosaccharides and contained only trace amounts of mannose (less than 1 residue/three to four chains). The second fraction contained the majority of the [ 3H]mannose originally in monomer, but no 35S activity. This fraction appears to contain oligosaccharide-peptides of the asparagine-N-glycosylamine type because there were no reduced sugars present and the alkaline borohydride treatment extensively degraded the core protein. The composition of the oligosaccharides, with high proportions of mannose, N-acetylglucosamine, galactose, and sialic acid, was consistent with this suggestion. The third fraction consisted of a series of oligosaccharides with sizes between three to six saccharides. They contained N-acetylgalactosaminitol, indicating that they were attached to the core protein by O-glycoside bonds between N-acetylgalactosamine and hydroxyl groups on serine and threonine. Thus, proteoglycans contain two classes of oligosaccharides, a mannose-rich class characteristic of glycoproteins and an O-glycoside class characteristic of mucins, in addition to the chondroitin sulfate and keratan sulfate chains.
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8.
  • Hjalmarsson, Karin J., et al. (författare)
  • Purification and characterization of transfer RNA (guanine-1)methyltransferase from Escherichia coli
  • 1983
  • Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 258:2, s. 1343-1351
  • Tidskriftsartikel (refereegranskat)abstract
    • The tRNA modifying enzyme, tRNA (guanine-1)methyltransferase has been purified to near homogeneity from an overproducing Escherichia coli strain harboring a multicopy plasmid carrying the structural gene of the enzyme. The preparation gives a single major band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme is probably a single polypeptide chain of molecular weight 32,000. The amino acid composition is presented and the NH2-terminal amino acid sequence was established to be H2N-Met-Trp-Ile-Gly-Ile-Ile-Ser-Leu-Phe-Pro. The enzyme has a pI of 5.2. The tRNA (guanine-1)-methyltransferase has a pH optimum of 8.0-8.5, an apparent Km of 5 microM for S-adenosylmethionine. S-adenosylhomocysteine is a competitive inhibitor for the enzyme with an apparent Ki of 6 microM. Spermidine or putrescine are not required for activity, but they stimulate the rate of methylation 1.2-fold with optima at 2 and 6 mM, respectively. Ammonium ion is not required and is inhibitory at concentrations above 0.15 M. Magnesium ion inhibited the activity at a concentration as low as 2 mM. Sodium and potassium ions were inhibitory at concentrations above 0.1 M. The molecular activity of tRNA (guanine-1)-methyltransferase was calculated to 10.0 min-1. It was estimated that the enzyme is present at 80 molecules/genome in cells growing with a specific growth rate of 1.0.
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