Biomedical subjects

M Kiso

Publications and source records attributed to M Kiso.

At least 37 records · Page 2Linked to original sources

PubMed1999

Antibodies to GD1alpha and to GQ1beta in Guillain-Barré syndrome and the related disorders.

Certain species of anti-ganglioside antibodies are associated with specific clinical features in various neurologic diseases. Serum autoantibodies to these minor gangliosides were investigated in a number of neurological diseases in order to examine the biological functions of GD1alpha and GQ1beta. Eleven patients with Guillain-Barré syndrome had remarkably high IgG anti-GD1alpha antibody titers, but no GD1alpha was detected in human peripheral nerve. An absorption study showed that IgG anti-GD1alpha antibodies from eight of the 11 patients were significantly absorbed by GD1a and GM1b, indicative that the IgG anti-GD1alpha antibodies cross-react with GD1a and GM1b. Both GD1a and GM1b have been reported to be target molecules for serum antibodies in certain patients with Guillain-Barré syndrome. GD1alpha may induce the production of IgG anti-GD1alpha antibody which cross-reacts with GD1a or GM1b, and subsequently functions in the development of Guillain-Barré syndrome. The IgGs from six patients with Fisher's syndrome who had the anti-GQ1beta antibody had anti-GQ1b activity as well. All the patients had external ophthalmoplegia, but no GQ1beta was detected in the human oculomotor nerve, further evidence that GQ1b, not GQ1beta, is the molecule targeted by the autoantibody in Fisher's syndrome.

Antibody Specificity↗

PubMed1999

Molecular cloning of a novel alpha2,3-sialyltransferase (ST3Gal VI) that sialylates type II lactosamine structures on glycoproteins and glycolipids.

A novel member of the human CMP-NeuAc:beta-galactoside alpha2, 3-sialyltransferase (ST) subfamily, designated ST3Gal VI, was identified based on BLAST analysis of expressed sequence tags, and a cDNA clone was isolated from a human melanoma line library. The sequence of ST3Gal VI encoded a type II membrane protein with 2 amino acids of cytoplasmic domain, 32 amino acids of transmembrane region, and a large catalytic domain with 297 amino acids; and showed homology to previously cloned ST3Gal III, ST3Gal IV, and ST3Gal V at 34, 38, and 33%, respectively. Extracts from L cells transfected with ST3Gal VI cDNA in a expression vector and a fusion protein with protein A showed an enzyme activity of alpha2, 3-sialyltransferase toward Galbeta1,4GlcNAc structure on glycoproteins and glycolipids. In contrast to ST3Gal III and ST3Gal IV, this enzyme exhibited restricted substrate specificity, i.e. it utilized Galbeta1,4GlcNAc on glycoproteins, and neolactotetraosylceramide and neolactohexaosylceramide, but not lactotetraosylceramide, lactosylceramide, or asialo-GM1. Consequently, these data indicated that this enzyme is involved in the synthesis of sialyl-paragloboside, a precursor of sialyl-Lewis X determinant.

Amino Acid Sequence↗

PubMed1999

Structural basis for the resistance of Tay-Sachs ganglioside GM2 to enzymatic degradation.

To understand the reason why, in the absence of GM2 activator protein, the GalNAc and the NeuAc in GM2 (GalNAcbeta1-->4(NeuAcalpha2-->3)Galbeta1-->4Glcbet a1-1'Cer) are refractory to beta-hexosaminidase A and sialidase, respectively, we have recently synthesized a linkage analogue of GM2 named 6'GM2 (GalNAcbeta1-->6(NeuAcalpha2-->3)Galbeta1-->4Glcbet a1-1'Cer). While GM2 has GalNAcbeta1-->4Gal linkage, 6'-GM2 has GalNAcbeta1-->6Gal linkage (Ishida, H., Ito, Y., Tanahashi, E., Li, Y.-T., Kiso, M., and Hasegawa, A. (1997) Carbohydr. Res. 302, 223-227). We have studied the enzymatic susceptibilities of GM2 and 6'GM2, as well as that of the oligosaccharides derived from GM2, asialo-GM2 (GalNAcbeta1-->4Galbeta1--> 4Glcbeta1-1'Cer) and 6'GM2. In addition, the conformational properties of both GM2 and 6'GM2 were analyzed using NMR spectroscopy and molecular mechanics computation. In sharp contrast to GM2, the GalNAc and the Neu5Ac of 6'GM2 were readily hydrolyzed by beta-hexosaminidase A and sialidase, respectively, without GM2 activator. Among the oligosaccharides derived from GM2, asialo-GM2, and 6'GM2, only the oligosaccharide from GM2 was resistant to beta-hexosaminidase A. Conformational analyses revealed that while GM2 has a compact and rigid oligosaccharide head group, 6'GM2 has an open spatial arrangement of the sugar units, with the GalNAc and the Neu5Ac freely accessible to external interactions. These results strongly indicate that the resistance of GM2 to enzymatic hydrolysis is because of the specific rigid conformation of the GM2 oligosaccharide.

Acetylgalactosamine↗

PubMed1999

Ganglioside GD1 alpha analogues as high-affinity ligands for myelin-associated glycoprotein (MAG).

The first systematic synthesis of ganglioside GD1 alpha analogues carrying N-acetyldeoxyneuraminic acids linked to C-6 of the GalNAc residue was accomplished. The suitably protected GM1b pentasaccharide derivative was regioselectively glycosylated with the phenyl 2-thioglycosides of 7-deoxy, 8-deoxy, and 9-deoxy-N-acetylneuraminic acid promoted by N-iodosuccinimide (NIS)-trifluoromethanesulfonic acid (TfOH) in acetonitrile, and the resulting hexasaccharides were converted to the target GD1 alpha analogues. All of the analogues retained excellent efficiency in supporting the adhesion to myelin-associated glycoprotein (MAG), raising the possibility that the internal sialic acid linked to the GalNAc residue may be replaced by other anionic substituents, in contrast to the terminal sialic acid, which is essential for MAG binding.

Animals↗

PubMed1999

Regulation of selectin binding activity by cyclization of sialic acid moiety of carbohydrate ligands on human leukocytes.

We provide here evidence that supports the occurrence of a biologically dormant form of selectin ligand carbohydrate, the sialyl 6-sulfo Lewis X containing modified sialic acid, in human leukocytes. The modification of sialic acid involves first de-N-acetylation of sialic acid moiety through ubiquitous de-N-acetylation/re-N-acetylation cycle, followed by the dehydrative cyclization of de-N-acetyl sialic acid to form "cyclic sialic acid." The enzyme involved in the dehydration of de-N-acetyl sialic acid is a calcium-dependent enzyme having neutral-alkaline pH optimum. De-N-acetyl sialyl 6-sulfo Lewis X retained selectin binding activity as well as parental sialyl 6-sulfo Lewis X, but cyclic sialyl 6-sulfo Lewis X was devoid of selectin binding activity. Sialyl 6-sulfo Lewis X carrying the cyclic sialic acid is specifically recognized by the newly generated mAb, G159. The determinant was distributed widely among normal human leukocytes, especially on monocytes and subsets of lymphocytes including NK cells, helper memory T cells, Tcr-gammadelta T cells, and a part of B cells. The determinant was detected also on several cultured lymphocytic leukemia cell lines and O-tetradecanoylphorbol 13-acetate-activated lymphoid cells. Cyclic sialyl 6-sulfo Lewis X is efficiently formed by the action of the partly membrane-bound calcium-dependent enzyme, tentatively called "sialic acid cyclase," and a possible physiological significance of this reaction could be a rapid inactivation of selectin binding activity at the cell surface. Conversely, the accumulated intracellular cyclic sialyl 6-sulfo Lewis X determinant may function as a dormant pool of selectin ligands, which, on appropriate stimulation, is hydrolyzed and becomes active in selectin-dependent cell adhesion.

Antigens, CD↗

PubMed1999

Total synthesis of a cholinergic neuron-specific ganglioside GT1a alpha: a high affinity ligand for myelin-associated glycoprotein (MAG).

An efficient total synthesis of a cholinergic neuron-specific ganglioside GT1a alpha (IV3NeuAcIII6NeuAcII3NeuAc-GgOse4Cer) is described. The suitably protected sialyl-alpha(2-->6)-gangliotriose (III6NeuAc-GgOse3) derivative was glycosylated with the phenyl 2-thioglycoside of sialic acid in the presence of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethane-sulfonate (TMSOTf) in acetonitrile medium, giving the disialogangliotriose (III6NeuAcII3NeuAc-GgOse3) derivative which contains both sialyl-alpha(2-->6)-GalNAc and sialyl-alpha(2-->3)-Gal structures (Route I). This pentasaccharide was efficiently synthesized also by the coupling of (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2-nonulopyranosylonate)-(2-->6)-2-deoxy-3,4-O-isopropylidene-2-ph thalimido-D-galactopyranosyl trichloroacetimidate with 2-(trimethylsilyl)ethyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2-nonulopyranosylonate)-(2-->3)-(2,6-di-O-benzyl-beta-D-galactopy ranosyl)-(1-->4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, followed by conversion of the phthalimido group to the acetamido group (Route II). O-Deisopropylidenation and further glycosylation with methyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-gala ct-2-nonulopyranosylonate)-(2-->3)-2,4,6-tri-O-benzoyl-1-thio-b eta-D-galactopyranoside, promoted by dimethyl(methylthio)sulfonium triflate (DMTST), gave the desired trisialogangliotetraose (IV3NeuAcIII6NeuAcII3NeuAc-GgOse4) derivative, which was converted stepwise into the title ganglioside GT1a alpha by the introduction of the ceramide part and then complete deprotection. The ganglioside obtained was shown to be identical with the native GT1a alpha on TLC-immunostaining.

Animals↗

PubMed1999

The structural basis for the susceptibility of gangliosides to enzymatic degradation.

The conformational properties of GM2, GalNacbeta-4(Neu5Acalpha-3) Galbeta-4Glcbeta-1Cer have been compared to those of 6'-GM2, in which the linkage between the GalNAc and Gal was altered from GalNacbeta-4Galbeta- to GalNacbeta-6Galbeta-, and to those of GD1a, Neu5Acalpha-3Galbeta-3GalNAcbeta-4(Neu5Acalpha-3 )Galbeta-4Glcbeta-1Cer, and GalNAc-GD1a. Our results revealed that unlike the compact and rigid oligosaccharide head group found in GM2, where the Neu5Ac and the GalNAc residues interact, the sugar chain of 6'-GM2 is in an open spatial arrangement, with the Neu5Ac no longer interacting with GalNAc, freely accessible to external interactions. The structure of GD1a can be regarded as that of GM2 with an extension of the terminal Neu5Acalpha-3Galbeta-disaccharide. The inner portion of GD1a is that of GM2 comprising the very rigid GalNAc-[Neu5Ac-]Gal trisaccharide. The terminal Neu5Ac-Gal linkage is flexible and fluctuates between two limiting conformations. In GalNAc-GD1a the outer sialic acid gains conformational rigidity due to the presence of the outer GalNAc in position 4 of galactose. This ganglioside has two 'core' GalNAc-[Neu5Ac-]Gal trisaccharide linked in tandem.

Carbohydrate Sequence↗

PubMed1999

Ganglioside GM(1a) on the cell surface is involved in the infection by human rotavirus KUN and MO strains.

Rotavirus is the most common cause of severe gastroenteritis in infants and children worldwide. The cell attachment of most animal rotaviruses, which belong to the neuraminidase-sensitive strains, requires sialic acid residues on the host cell membranes. On the other hand, most human rotaviruses are classified as neuraminidase-insensitive strains. The involvement of gangliosides on the host cell surface in human rotavirus infection was investigated by immunostaining analysis of target cells, and by assaying the neutralization of infection by rotavirus and the blocking of target cellular receptors. In host cells (MA104 cells) pretreated with Arthrobacter ureafaciens neuraminidase, which were still infected by human rotaviruses (KUN and MO strains), GM(3) was hydrolyzed markedly by the neuraminidase, while GM(1a) was not hydrolyzed at all. Infection by the rotaviruses was strongly inhibited by exogenous ganglioside GM(1a), but not GA(1). Infection was also inhibited by pretreatment of the MA104 cells with cholera toxin B-subunit, which specifically blocked ganglioside GM(1a) on the plasma membrane. The treatment of MA104 cells with the endoglycoceramidase attenuated human rotavirus infection. From these findings, we concluded that GM(1a) on the plasma membrane of the host cells was involved in the infection by human rotavirus KUN and MO strains.

Animals↗

PubMed1999

Activity of monosaccharide lipid A analogues in human monocytic cells as agonists or antagonists of bacterial lipopolysaccharide.

The lipid A portion of bacterial lipopolysaccharide (LPS) plays a central role in the production of endotoxic mediators. Different responses between human and murine macrophages to lipid A-like structures have been indicated. We investigated a series of structurally related monosaccharide lipid A analogues for their potency to activate human macrophage U937 cells and peripheral blood mononuclear cells for production of tumor necrosis factor-alpha and interleukin-6 compared with their potency to activate murine macrophage RAW264.7 cells. Two of the analogues were found to have sufficient potency to activate the human cells as well as the murine cells. These analogues comprise D-glucosamine, phosphoryl groups, and acyl groups of defined carbon chain lengths (C(14) and C(12)) in a ratio of 1:1:3. This ratio of molecular constituents is proportional to that of the complete disaccharide structure of lipid A (2:2:6). Other analogues with two or four C(14) acyl groups and with three acyl groups but including a C(10) or a C(16) acyl group, which are active to murine cells, showed no LPS-agonistic activity, but did show LPS-antagonistic activity, to human cells. An LPS-antagonistic analogue in the murine cells also showed antagonistic activity in human cells. These results reveal that lipid A analogues recognized as being LPS agonists by human macrophages have common structural features in monosaccharide and disaccharide structures which are more strict than those required for recognition by murine macrophages and that broad lipid A-like structures are recognized as being LPS antagonists by human cells but are recognized by murine cells as being either LPS agonists or antagonists.

Animals↗

PubMed1998

Glycan specificity of myelin-associated glycoprotein and sialoadhesin deduced from interactions with synthetic oligosaccharides.

Myelin-associated glycoprotein (MAG) and sialoadhesin (Sn) bind to sialylated glycans on cell surfaces and are thought to be involved in cell-cell interactions. In order to investigate how the interactions of these proteins are influenced by the glycan structure, we compared the inhibitory potencies of different synthetic monovalent oligosaccharides and polyvalent polyacrylamide derivatives. Using oligosaccharides with modifications in the sialic acid, galactose or N-acetylglucosamine moieties, we could demonstrate that both MAG and Sn bind with high preference to alpha2,3-linked sialic acid and interact at least with the three terminal monosaccharide units. For MAG, contacts with even more distant monosaccharides are likely, since pentasaccharides are bound better than trisaccharides. Also, an additional sialic acid at position six of the third-terminal monosaccharide unit enhances binding to MAG, whereas it does not influence binding to Sn significantly. Modifications of the sialic acid glycerol side chain demonstrated that the hydroxy groups at positions 8 and 9 are required for binding to both proteins. Surprisingly, MAG binds 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid significantly better than N-acetylneuraminic acid, whereas Sn prefers the latter structure. These results indicate that the interactions of MAG and Sn are mainly with sialic acid and that additional contacts with the subterminal galactose and N-acetylglucosamine residues also contribute to the binding strength, although to a lesser degree.

Animals↗

PubMed1998

Myelin-associated glycoprotein binding to gangliosides. Structural specificity and functional implications.

Myelin-associated glycoprotein (MAG), which mediates certain myelin-neuron cell-cell interactions, is a lectin that binds to sialylated glycoconjugates. Gangliosides, the most abundant sialylated glycoconjugates in the brain, may be the functional neuronal ligands for MAG. Cells engineered to express MAG on their surface adhered specifically to gangliosides bearing an alpha 2,3-linked N-acetylneuraminic acid on a terminal galactose, with the following relative potency: GQ1b alpha >> GD1a, GT1b >> GM3, GM4 (GM1, GD1b, GD3, and GQ1b did not support adhesion). MAG binding was abrogated by modification of the carboxylic acid, any hydroxyl, or the N-acetyl group of the ganglioside's N-acetylneuraminic acid moiety. Related immunoglobulin (Ig) superfamily members either failed to bind gangliosides (CD22) or bound with less stringent specificity (sialoadhesin), whereas a modified form of MAG (bearing three of its five extra-cellular Ig-like domains) bound only GQ1b alpha. Enzymatic removal of sialic acids from the surface of intact nerve cells altered their functional interaction with myelin. These data are consistent with a role for gangliosides in MAG-neuron interactions.

Animals↗

PubMed1998

Specific detection of sialyl Lewis X determinant carried on the mucin GlcNAcbeta1-->6GalNAcalpha core structure as a tumor-associated antigen.

Sialyl Lewis X serves as a ligand for selectins and is proposed to be implicated in hematogenous metastasis of cancers. When a cultured human breast cancer cell line, MCF-7, which does not express sialyl Lewis X, was transfected with human fucosyltransferase VI cDNA, a strong expression of sialyl Lewis X was induced on transfectant cells. The transfectant cells were found to be also reactive to the antibody NCC-ST-439, which was initially raised against human gastric cancer cells and later was shown to recognize a tumor-associated carbohydrate antigen in breast, gastric, and colon cancers. This suggested that the antigen recognized by NCC-ST-439 is closely related to sialyl Lewis X. Subsequent studies indicated that NCC-ST-439 specifically reacts to NeuAcalpha2-->3Galbeta1-->4(Fucalpha1-->3)GlcNAcbet a1-->6GalNAcalpha1 -->R, the sialyl Lewis X on the mucin GlcNAcbeta1-->6 GalNAcalpha structure. The antibody was not reactive to the conventional sialyl Lewis X determinants on straight and/or branched polylactosamine structures including NeuAcalpha2-->3Galbeta1-->4(Fucalpha1-->3)GlcNAcbet a1-->3Galbeta1-->4 Glcbeta1-->R and NeuAcalpha2-->3Galbeta1-->4(Fucalpha1-->3)GlcNAcbet a1-->6Galbeta1-->4 Glcbeta1-->R. This was in clear contrast to most of the known anti-sialyl Lewis X antibodies, which do not discriminate internal structures carrying the sialyl Lewis X determinant. On the other hand, the newly generated monoclonal antibody GSC154-27 had a specificity completely the reverse of the specificity of NCC-ST-439 in that it was strongly reactive to the conventional sialyl Lewis X determinants in straight and branched polylactosamine structures, while far less reactive to the sialyl Lewis X determinant on the mucin GlcNAcbeta1-->6GalNAcalpha core structure. A set of these two antibodies would be useful in discriminating the molecular species of sialyl Lewis X expressed by malignant cells and in studying their functional significance.

Antibodies, Monoclonal↗

PubMed1998

Identification of a major carbohydrate capping group of the L-selectin ligand on high endothelial venules in human lymph nodes as 6-sulfo sialyl Lewis X.

We investigated the molecular species of sulfated sialyl Lewis X determinants, the putative L-selectin ligand, expressed on high endothelial venules (HEV) in human lymph nodes. Comparison of the reactivity pattern of HEV with the reactivity of the pure 6-sulfo, 6'-sulfo, or 6,6'-bissulfo sialyl Lewis X determinant with hitherto known anti-sialyl Lewis X antibodies strongly suggested 6-sulfo sialyl Lewis X to be the best candidate for the major sulfated sialyl Lewis X determinant on HEV, followed by 6,6'-bissulfo sialyl Lewis X, whereas 6'-sulfo sialyl Lewis X was unlikely. We newly generated monoclonal antibodies (mAbs) G152 and G72 directed against 6-sulfo sialyl Lewis X, which intensely labeled HEV in immunohistochemical examination and inhibited binding of recombinant L-selectin-IgG to HEV, suggesting that the determinant serves as a ligand for L-selectin. To test the concomitant expression of 6, 6'-bissulfo sialyl Lewis X, specific mAbs (G2706, G27011, G27037, and G27039) were generated, but all antibodies failed to react to HEV. Next, we established mAbs (AG97 and AG273) directed against 6-sulfo Lewis X, the asialo form of 6-sulfo sialyl Lewis X. The antibodies were not reactive to untreated HEV, but strongly reacted to sialidase-treated HEV. This indicated the predominance of the sialylated form of 6-sulfo sialyl Lewis X and minimal expression of its asialo form, corroborating that it was synthesized by fucosyltransferase VII, the isoenzyme that preferentially produces the sialylated form of the determinant.

Antibodies, Monoclonal↗

PubMed1998

Synthesis of sialyl LeX ganglioside analogues modified at C-6 of the galactose residue to elucidate the mechanism of selection recognition.

Sialyl Lewis X ganglioside analogues modified at C-6 of the galactose residue, having 6-O-methoxy, 6-acetamido and 6-amino functional groups, have been synthesized. Treatment of 2-(trimethylsilyl)ethyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5- dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosylonate)-(2-->3)- 2-O-benzoyl -beta-D-galactopyranoside with trimethyloxonium tetrafluoroborate or Tf2O, followed by NaN3, gave the 6-O-methyl and 6-azido derivatives, respectively, which were converted into their respective methyl 1-thioglycoside derivatives. The glycosyl donors obtained were coupled with 2-(trimethylsilyl)ethyl 2- acetamido-6-O-benzyl-2-deoxy-3-O-(4-methoxybenzyl)-beta-D-glucopyranosyl - (1-->)-2,4,6-tri-O-benzyl-beta-D-galactopyranosyl-(1-->4)-2,3,6-tri-O-be nzyl- beta-D-galactopyranoside in the presence of dimethyl(methylthio)sulfonium triflate (DMTST) to give their respective pentasaccharides. The glycosylation of the pentasaccharide acceptors derived from their precursors by removal of the 4-methoxybenzyl group, with phenyl 1-thioglycoside derivative of L-fucose using N-iodosuccinimide-TfOH afforded the corresponding hexasaccharides, which were transformed in good yield, via reductive removal of the benzyl group, the simultaneous transformation of azide to amine and acetamide, Omicron-deacylation and saponification of the methyl ester into the target compounds without the ceramide groups. On the other hand, the proper manipulation of the protecting group of the hexasaccharides, including a transformation of azide into acetamide and trifluoroacetamide, gave the hexasaccharide imidates, which were coupled with (2S,3R,4E)-2-azido-o-O-tert-butyldipenhylsilyl-4-o ctadecene-1,3-diol. Selective reduction of the azido group, N-acylation with octadecanoic acid, and the complete removal of the protecting groups gave the desired sialyl LeX ganglioside analogues.

Carbohydrate Sequence↗

PubMed1998

Synthesis of sialyl Lewis X pentasaccharide analogue for high-throughput screening of selectin blockers.

We have developed an effective synthesis of sLe(x) pentasaccharide glycolipid analogue 2. As a part of application of sLe(x) pentasaccharide glycolipid 2 synthesized here, we have investigated the construction of a high-through-put screening system for discovery of selectin blockers. As a result, it was found that compound 2 was a useful ligand for in vitro ELISA assay and could be an important material for high-throughput screening of selectin blockers.

Carbohydrate Conformation↗

PubMed1998

Detailed acceptor specificities of human alpha1,3-fucosyltransferases, Fuc-TVII and Fuc-TVI.

To clarify the acceptor specificity of Fuc-TVII, its activity toward various analogs of a 2-(trimethylsilyl)ethyl alpha2,3-sialyl lacto-N-neotetraose, an acceptor for both Fuc-TVII and Fuc-TVI, was examined in comparison with that of Fuc-TVI. Fuc-TVII required three portions of alpha2,3-sialylated type-2 oligosaccharide structures (i.e., the hydroxyl group at C-4 of Gal, the hydroxyl group at C-3 of GlcNAc, and the carbonylamino group at C-2 of GlcNAc) for its acceptor recognition. Fuc-TVI required the carbonylamino group at C-2 of GlcNAc for its acceptor recognition. Fuc-TVII showed higher affinity toward two analogs, in which the hydroxyl group at C-6 of GlcNAc has been deoxygenated and the acetamide group of N-acetylneuraminic acid has been replaced with a glycolylamino group, respectively, than that toward the original compound. On the other hand, Fuc-TVI showed higher affinity toward an analog, in which the acetamide group of GlcNAc has been modified with a lauroylamino group, than that toward the original compound. Analysis involving mass spectrometry confirmed that both Fuc-TVII and Fuc-TVI could fucosylate these three analogs to yield sialyl Lewis x derivatives.

Binding, Competitive↗

PubMed1998

Specificity of the N1 and N2 sialidase subtypes of human influenza A virus for natural and synthetic gangliosides.

Sialyl-linkage specificity of sialidases of the human influenza A virus strains, A/Aichi/2/68 (H3N2) and A/PR/8/34 (H1N1) were studied using natural and synthetic gangliosides. The sialidase of the A/Aichi/2/68 strain hydrolyzed the terminal Neu5Acalpha2-3Gal sequence but not the Neu5Acalpha2-3 linkage on the inner Gal of GM1a, which is a ganglioside that has the gangliotetraose chain (Galbeta1-3GalNAcbeta1-4-(Neu5Acalpha2-3)Galbeta1++ +-4Glcbeta1-Cer). The sialidase hydrolyzed the Neu5Ac on the inner Gal of GM2, which had a shorter gangliotriose chain. GM4, which had the shortest chain (Neu5Acalpha2-3Galbeta1-Cer) of the gangliosides, had a lower substrate specificity. The N1 and N2 sialidase subtypes of the human influenza A virus had no significant variation in their substrate specificity for the gangliosides. Analysis of 11 synthetic gangliosides, which contained various ceramide or sialic acid moieties, demonstrated that A/Aichi/2/68 (H3N2) sialidase recognized the ceramide and sialic acid moiety and the length and structure of the sialyl sugar chain.

Carbohydrate Sequence↗

PubMed1998

In vitro and in vivo selectin-blocking activities of sulfated lipids and sulfated sialyl compounds.

There is accumulating evidence that sulfated lipids, sulfated oligosaccharides and other sulfated compounds are reactive with selectins in a manner that interferes with selectin interactions with their natural ligands. In the report we describe the ability of sulfated lipids (sulfatides and gangliosides) and multimeric forms of sulfated sialic acid to block binding of P- and E-selectin-Ig to neutrophils. The in vivo ability of these compounds to block lung injury in rats following i.v. infusion of purified cobra venom factor (CVF), which induces injury that is L- and P-selectin dependent, was also determined as well as effects on recruitment of neutrophils, as measured by lung myeloperoxidase. There was a significant correlation between the ability of sulfated lipids and sialyl compounds to interfere in vitro with P-selectin-Ig binding to neutrophils and to protect against P-selectin-dependent acute lung injury induced by CVF. The biological effects of these sulfated compounds were also associated with diminished accumulation of neutrophils. The protective effects of these compounds may be linked to their ability to interfere with P-selectin binding to counter-receptors on neutrophils.

Animals↗