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At least 1,081 records · Page 60Linked to original sources
PubMed1991

Identification of glycoconjugates which are targets for anti-Gal(beta 1-3)GalNAc autoantibodies in spinal motor neurons.

Human IgM anti-Gal(beta 1-3)GalNAc antibodies which bind to GM1 and GD1b, are implicated in the pathogenesis of predominantly motor neuropathy or motor neuron disease. By immunofluorescence microscopy, the human antibodies immunostain the surface of motor neurons from bovine spinal cord. The motor neurons are also immunostained by cholera toxin (CT), which is specific for GM1. Glycolipid analysis using thin-layer chromatography (TLC) and immunostaining reveals that the relative concentration of GM1 and GD1b in motor neurons is greatly reduced in comparison to whole spinal cord, and that other motor neuron gangliosides are unreactive with the anti-Gal(beta 1-3)GalNAc antibodies. By Western blot analysis, the antibodies react with several protein bands in motor neuron extracts, and many of the same proteins are also recognized by PNA. These data suggest that both glycoproteins and glycolipids might be targets for anti-Gal(beta 1-3)GalNAc antibodies in spinal motor neurons.

Animals↗
PubMed1993

Characterization of novel fucosyl- and tyvelosyl-containing glycoconjugates from Trichinella spiralis muscle stage larvae.

The monosaccharide composition of an affinity-purified family of antigenically-related Trichinella spiralis larval glycoproteins was determined by gas chromatography/mass spectrometry. This group of 6 major glycoproteins, designated TSL-1, originates in the muscle stage (L1) larval stichosome. They are present on the L1 surface and in excretory/secretory products of L1 larvae, are stage-specific, and are highly immunodominant. The glycosyl composition of the TSL-1 antigens was remarkable in 2 respects: (1) fucose accounted for 36 molar percent of the glycosyl residues; and (2) a 3,6-dideoxyhexose was identified, which accounted for at least 24 molar percent of the glycosyl residues. Previously, 3,6-dideoxyhexoses have been found only in certain Gram-negative bacterial lipopolysaccharides and in ascaroside alcohols (ascarylose) of Ascaris eggs. The 3,6-dideoxyhexose found in the TSL-1 antigens also was found in ES. This Trichinella sugar has been chemically identified as a 3,6-dideoxyarabinohexose, the same as found in Ascaris eggs. However, the absolute configuration of the TSL-1 sugar is D-(tyvelose), not L-(ascarylose) as is found in Ascaris eggs. Methylation analysis indicated that the TSL-1 3,6-dideoxy-D-arabinohexose was present entirely as non-reducing terminal residues. Approximately 83% of the fucose was also present as non-reducing terminal residues, with the remaining fucose found as 3,4-linked branched residues.

Animals↗
PubMed1994

Recognition of the major cell surface glycoconjugates of Leishmania parasites by the human serum mannan-binding protein.

Activation of complement on the surface of parasitic protozoa of the genus Leishmania appears to be important for parasite infectivity in the mammalian host, as it allows these parasites to attach to and invade macrophages via their surface complement receptors. Serum mannan-binding protein (MBP) is a known activator of complement. Therefore, in the present study, we have investigated whether serum MBP binds to live Leishmania parasites, and to mannose-containing saccharides derived from the parasite cell surface. We have observed by fluorescence microscopy that biotinylated MBP binds to the surface of L. major and L. mexicana promastigotes. At this developmental stage the parasites are coated by a mannose-containing lipophosphoglycan (LPG). We have observed that radioiodinated MBP binds in a mannose-inhibitable manner to purified LPG which has been immobilized in plastic microwells, as well as to purified mannose-terminating di-, tri- and tetrasaccharide fragments ('cap' structures) which have been released by mild acid hydrolysis from the outer chains of the LPG, converted into neoglycolipids and resolved by thin-layer chromatography. 125I-MBP also binds in the chromatogram-binding assay to the mannose-containing glycoinositol-phospholipids that are expressed in high copy number on both the promastigote and the intracellular amastigote stages of most Leishmania species. These data suggest that MBP has the potential to opsonize the major developmental stages of Leishmania parasites, and provide a possible mechanism for the antibody-independent activation of complement on their surface.

Animals↗
PubMed1992

Purification and some properties of L-fucose dehydrogenase from Agrobacterium radiobacter and its application to the assay of bound-fucose in glycoconjugates.

L-Fucose dehydrogenase was found in the cell extract of Agrobacterium radiobacter and purified to homogeneity about 480-fold with 16% recovery. The molecular weight of the enzyme was approx. 64,000. The enzyme was active in the neutral pH range, unlike other L-fucose or D-arabinose dehydrogenases which are active only in the alkaline pH range. Using this enzyme and alpha-L-fucosidase F-I of Bacillus circulans (Tsuji, Y., Yamamoto, K., Tochikura, T., Seno, T., Ohkubo, Y. and Yamaguchi, H. (1990) J. Biochem. 107, 324-330) simultaneously, we developed a new coupled enzymatic method in a single buffer system for determining bound-fucose in biological materials. The fucose released by alpha-L-fucosidase F-I was oxidized with L-fucose dehydrogenase in the presence of NAD+, and the NADH formed was measured by absorbance of ultraviolet or utilized to generate color in a reaction involving CuSO4 and neocuproine. Using these methods, bound-fucose in various oligosaccharides and proteins such as lacto-N-fucopentaoses and porcine gastric mucin were quantitated within 15 min.

Animals↗
PubMed1995

Microbial recognition of target-cell glycoconjugates.

Attachment of microbial protein to host cell-surface carbohydrate is considered essential for successful infection. Information of conceptual interest, including crystal structures of protein-saccharide complexes and convincing models of target membrane penetration, continues to emerge for viruses and bacterial toxins. Other important data relate to therapeutic receptor blockade, through the use of saccharide analogs or vaccines directed against the microbial adhesin.

Animals↗
PubMed1996

The antimetabolite Tiazofurin (TR) inhibits glycoconjugate biosynthesis and invasiveness of tumour cells.

We investigated the effect of Tiazofurin (TR-2-beta-D-furanosylthiazole-4-carbamide) on tumour cell invasion using metastatic 3LL-HH murine lung carcinoma and HT168-M1 human melanoma as experimental models. TR pretreatment of 3LL-HH cells, in a dose range of 15-60 microM, caused inhibition of cell proliferation, adhesion to plastic and extracellular matrix proteins. The TR-induced altered matrix interactions of 3LL-HH cells were reflected in decreased migration through matrix-covered filters. Analysis of the expression of certain invasion markers indicated that TR suppressed the expression of alpha v beta 3 integrin and MMP2 metalloproteinase. Biochemical studies indicated that 24 h 60 microM TR treatment of 3LL-HH cells inhibited glycosylation of a wide range of glycoproteins with the most pronounced effect on proteoglycans. TR pretreatment of 3LL-HH tumour cells resulted in the loss of lung colonisation potential in vivo. Furthermore, in vivo TR treatment inhibited the formation of liver metastases of 3LL-HH murine carcinoma. TR treatment also induced inhibition of integrin and MMP2 expression, migration and liver colonisation of the human melanoma HT168-M1 cell line. Since the TR concentration which inhibited various cellular functions was much lower for cell adhesion and lung colonisation than for cell proliferation, we suggest that the predominant effect of TR is the inhibition of metastasis in these model systems. We also suggest that both the effect of TR on tumour cell proliferation and on extracellular matrix interaction contribute to its remarkable antimetastatic potential in vivo.

Amino Acid Sequence↗