The species-specific Ca(2+)-dependent reaggregation of dissociated cells of the marine sponge Mic... more The species-specific Ca(2+)-dependent reaggregation of dissociated cells of the marine sponge Microciona prolifera is mediated by a large extracellular adhesion proteoglycan. The glycans of this molecule are involved in the interactions of the proteoglycan with itself and with the sponge cells. Monoclonal antibodies against the glycans block the aggregation of sponge cells (Misevic, G. N., Finne, J., and Burger, M. M. (1987) J. Biol. Chem. 262, 5870-5877). Proteoglycan oligosaccharides were prepared by partial acid hydrolysis of the isolated glycans, and their reactivity with the monoclonal antibodies was monitored after linkage to phospholipid and immunostaining of thin layer chromatograms. One major antibody-reactive oligosaccharide was detected and purified by ion-exchange chromatography and high performance liquid chromatography. 1H NMR spectroscopy, fast atom bombardment-mass spectrometry, methylation analysis, and sequential chemical and enzymatic degradation studies indicated the structure [formula: see text] for the oligosaccharide. The depyruvylated derivative of the oligosaccharide did not react with the aggregation-blocking antibody, which indicates that the pyruvate acetal is an essential part of the epitope.
A total of 378 streptococcal isolates of Lancefield groups B, C, D and G were tested for their ab... more A total of 378 streptococcal isolates of Lancefield groups B, C, D and G were tested for their ability to hemagglutinate untreated, sialidase-treated, and endo-beta-galactosidase-treated human erythrocytes. Of the 43 strains showing positive hemagglutination, 9 were inhibitable with neutral monosaccharides. Four strains were inhibited with galactose and N-acetylgalactosamine, whereas five were inhibited with galactose only. A third, sialic acid-specific adhesion activity was suggested for two additional strains on the basis of their agglutination of native and endo-beta-galactosidase-treated but not sialidase-treated erythrocytes. All the sugar-specific agglutination activities detected were confined to Streptococcus suis strains of group D streptococci, whereas streptococci of other groups did not exhibit these types of hemagglutination activities. The adhesins were sensitive to proteases and heat treatment, which indicates that they were proteins. The hemagglutinating isolates of ...
Eukaryotic organisms are continuously exposed to bacteriophages, which are efficient gene transfe... more Eukaryotic organisms are continuously exposed to bacteriophages, which are efficient gene transfer agents in bacteria. However, bacteriophages are considered not to pass the eukaryotic cell membrane and enter nonphagocytic cells. Here we report the binding and penetration of Escherichia coli PK1A2 bacteriophage into live eukaryotic neuroblastoma cells in vitro. The phage interacts with cell surface polysialic acid, which shares structural similarity with the bacterial phage receptor. Using fluorescence and electron microscopy, we show that phages are internalized via the endolysosomal route and persist inside the human cells up to one day without affecting cell viability. Phage capsid integrity is lost in lysosomes, and the phage DNA is eventually degraded. We did not detect the entry of phage DNA into the nucleus; however, we speculate that this might occur as a rare event, and propose that this potential mechanism could explain prokaryote–eukaryote gene flow.
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 2, 2017
Host cell surface carbohydrate receptors of bacterial adhesins are attractive targets in anti-adh... more Host cell surface carbohydrate receptors of bacterial adhesins are attractive targets in anti-adhesion therapy. The affinity of carbohydrate ligands with adhesins is usually found in a low µM range, which poses a problem for the design of effective inhibitors useful in therapy. In an attempt to increase the inhibitory power of carbohydrate ligands, we have combined the approach of chemical modification of ligands with their presentation as multivalent dendrimers in the design of an inhibitor of streptococcal adhesin SadP binding to its galactosyl-α1-4-galactose (galabiose) receptor. Using a phenylurea-modified galabiose-containing trisaccharide in a tetravalent dendrimeric scaffold, inhibition of adhesion at a low picomolar level was achieved. This study is an example of one of a few low picomolar inhibitors observed for bacterial adhesins and demonstrates a promising approach to develop anti-adhesives with the potential of practical applicability.
A galabiose disaccharide building block was synthesized by an efficient pectinase cleavage of pol... more A galabiose disaccharide building block was synthesized by an efficient pectinase cleavage of polygalacturonic acid and subsequent chemical functional group transformations. Besides the disaccharide, the corresponding trisaccharide was also obtained and modified. The compounds were subsequently conjugated to dendrimers with up to eight end groups using 'click' chemistry. The compounds were evaluated as inhibitors of adhesion of the pathogen Streptococcus suis in a hemagglutination assay and strong inhibition was observed for the tetra- and octavalent galabiose compound with MIC values in the low nanomolar range. The corresponding octavalent trisaccharide was a ca. 20-fold weaker inhibitor.
Glycan-protein interactions are of utmost importance in several biological phenomena. Although th... more Glycan-protein interactions are of utmost importance in several biological phenomena. Although the variety of carbohydrate residues in mammalian cells is limited to less than a dozen different sugars, their spatial topographical presentation in what is now associated as the "glycocodes" provides the fundamental keys for specific and high affinity "lock-in" recognition events associated with a wide range of pathologies. Toward deciphering our understanding of these glycocodes, chemists have developed new creative tools that included dendrimer chemistry in order to provide monodisperse multivalent glycoconjugates. This review provides a survey of the numerous aromatic architectures generated for the multivalent presentation of relevant carbohydrates using covalent attachment or supramolecular self-assemblies. The basic concepts toward their controlled syntheses will be described using modern synthetic procedures with a particular emphasis on powerful organometallic methodologies. The large variety of dendritic aromatic scaffolds, together with a brief survey of their unique biophysical and biological properties will be critically reviewed. The distinctiveness of the resulting multivalent glycoarchitectures, encompassing glycoclusters, glycodendrimers and molecularly defined self-assemblies, in forming well organized cross-linked lattices with multivalent carbohydrate binding proteins (lectins) together with their photophysical, medical, and imaging properties will also be briefly highlighted. The topic will be presented in increasing order of aromatic backbone complexities and will end with fullerenes together with self-assembled nanostructures, thus complementing the various scaffolds described in this special thematic issue dedicated to multivalent glycoscience.
Biochemical and Biophysical Research Communications, 1977
Abstract The occurence of disialosyl (α-N-acetylneuraminyl-(2→8)-N-acetylneuraminyl) groups in gl... more Abstract The occurence of disialosyl (α-N-acetylneuraminyl-(2→8)-N-acetylneuraminyl) groups in glycoproteins was studied. It was found by methylation analysis that 8.5 % of N-acetylneuraminic acid in brain glycoproteins was substituted at C-8. The corresponding value was 16.6 % in brain gangliosides. The substituent was identified as neuraminic acid from its lability to neuraminidase treatment. The results demonstrate that not only gangliosides contain disialosyl groups, but these are also found in glycoproteins. The group is present in several types of carbohydrate units, with the highest proportion in N-glycosidic chains of large molecular size.
The derivatives obtained by permethylation of unsubstituted 2-amino-2-deoxy-hexitols and of these... more The derivatives obtained by permethylation of unsubstituted 2-amino-2-deoxy-hexitols and of these compounds monosubstituted at C-3, C-4, or C-6, and disubstituted at C-3 and C-6, have been analysed by g.l.c.-m.s. Each derivative can be identified on the basis of retention time and mass spectrum. In methylation analysis, methanolysis gave one derivative of each hexitol, whereas a mixture of products was formed when degradation was effected by acetolysis followed by hydrolysis. An application in the analysis of amino-sugar linkages in alkali-labile O-glycosylic oligosaccharides from rat-brain glycoproteins is described.
The species-specific Ca(2+)-dependent reaggregation of dissociated cells of the marine sponge Mic... more The species-specific Ca(2+)-dependent reaggregation of dissociated cells of the marine sponge Microciona prolifera is mediated by a large extracellular adhesion proteoglycan. The glycans of this molecule are involved in the interactions of the proteoglycan with itself and with the sponge cells. Monoclonal antibodies against the glycans block the aggregation of sponge cells (Misevic, G. N., Finne, J., and Burger, M. M. (1987) J. Biol. Chem. 262, 5870-5877). Proteoglycan oligosaccharides were prepared by partial acid hydrolysis of the isolated glycans, and their reactivity with the monoclonal antibodies was monitored after linkage to phospholipid and immunostaining of thin layer chromatograms. One major antibody-reactive oligosaccharide was detected and purified by ion-exchange chromatography and high performance liquid chromatography. 1H NMR spectroscopy, fast atom bombardment-mass spectrometry, methylation analysis, and sequential chemical and enzymatic degradation studies indicated the structure [formula: see text] for the oligosaccharide. The depyruvylated derivative of the oligosaccharide did not react with the aggregation-blocking antibody, which indicates that the pyruvate acetal is an essential part of the epitope.
A total of 378 streptococcal isolates of Lancefield groups B, C, D and G were tested for their ab... more A total of 378 streptococcal isolates of Lancefield groups B, C, D and G were tested for their ability to hemagglutinate untreated, sialidase-treated, and endo-beta-galactosidase-treated human erythrocytes. Of the 43 strains showing positive hemagglutination, 9 were inhibitable with neutral monosaccharides. Four strains were inhibited with galactose and N-acetylgalactosamine, whereas five were inhibited with galactose only. A third, sialic acid-specific adhesion activity was suggested for two additional strains on the basis of their agglutination of native and endo-beta-galactosidase-treated but not sialidase-treated erythrocytes. All the sugar-specific agglutination activities detected were confined to Streptococcus suis strains of group D streptococci, whereas streptococci of other groups did not exhibit these types of hemagglutination activities. The adhesins were sensitive to proteases and heat treatment, which indicates that they were proteins. The hemagglutinating isolates of ...
Eukaryotic organisms are continuously exposed to bacteriophages, which are efficient gene transfe... more Eukaryotic organisms are continuously exposed to bacteriophages, which are efficient gene transfer agents in bacteria. However, bacteriophages are considered not to pass the eukaryotic cell membrane and enter nonphagocytic cells. Here we report the binding and penetration of Escherichia coli PK1A2 bacteriophage into live eukaryotic neuroblastoma cells in vitro. The phage interacts with cell surface polysialic acid, which shares structural similarity with the bacterial phage receptor. Using fluorescence and electron microscopy, we show that phages are internalized via the endolysosomal route and persist inside the human cells up to one day without affecting cell viability. Phage capsid integrity is lost in lysosomes, and the phage DNA is eventually degraded. We did not detect the entry of phage DNA into the nucleus; however, we speculate that this might occur as a rare event, and propose that this potential mechanism could explain prokaryote–eukaryote gene flow.
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 2, 2017
Host cell surface carbohydrate receptors of bacterial adhesins are attractive targets in anti-adh... more Host cell surface carbohydrate receptors of bacterial adhesins are attractive targets in anti-adhesion therapy. The affinity of carbohydrate ligands with adhesins is usually found in a low µM range, which poses a problem for the design of effective inhibitors useful in therapy. In an attempt to increase the inhibitory power of carbohydrate ligands, we have combined the approach of chemical modification of ligands with their presentation as multivalent dendrimers in the design of an inhibitor of streptococcal adhesin SadP binding to its galactosyl-α1-4-galactose (galabiose) receptor. Using a phenylurea-modified galabiose-containing trisaccharide in a tetravalent dendrimeric scaffold, inhibition of adhesion at a low picomolar level was achieved. This study is an example of one of a few low picomolar inhibitors observed for bacterial adhesins and demonstrates a promising approach to develop anti-adhesives with the potential of practical applicability.
A galabiose disaccharide building block was synthesized by an efficient pectinase cleavage of pol... more A galabiose disaccharide building block was synthesized by an efficient pectinase cleavage of polygalacturonic acid and subsequent chemical functional group transformations. Besides the disaccharide, the corresponding trisaccharide was also obtained and modified. The compounds were subsequently conjugated to dendrimers with up to eight end groups using 'click' chemistry. The compounds were evaluated as inhibitors of adhesion of the pathogen Streptococcus suis in a hemagglutination assay and strong inhibition was observed for the tetra- and octavalent galabiose compound with MIC values in the low nanomolar range. The corresponding octavalent trisaccharide was a ca. 20-fold weaker inhibitor.
Glycan-protein interactions are of utmost importance in several biological phenomena. Although th... more Glycan-protein interactions are of utmost importance in several biological phenomena. Although the variety of carbohydrate residues in mammalian cells is limited to less than a dozen different sugars, their spatial topographical presentation in what is now associated as the "glycocodes" provides the fundamental keys for specific and high affinity "lock-in" recognition events associated with a wide range of pathologies. Toward deciphering our understanding of these glycocodes, chemists have developed new creative tools that included dendrimer chemistry in order to provide monodisperse multivalent glycoconjugates. This review provides a survey of the numerous aromatic architectures generated for the multivalent presentation of relevant carbohydrates using covalent attachment or supramolecular self-assemblies. The basic concepts toward their controlled syntheses will be described using modern synthetic procedures with a particular emphasis on powerful organometallic methodologies. The large variety of dendritic aromatic scaffolds, together with a brief survey of their unique biophysical and biological properties will be critically reviewed. The distinctiveness of the resulting multivalent glycoarchitectures, encompassing glycoclusters, glycodendrimers and molecularly defined self-assemblies, in forming well organized cross-linked lattices with multivalent carbohydrate binding proteins (lectins) together with their photophysical, medical, and imaging properties will also be briefly highlighted. The topic will be presented in increasing order of aromatic backbone complexities and will end with fullerenes together with self-assembled nanostructures, thus complementing the various scaffolds described in this special thematic issue dedicated to multivalent glycoscience.
Biochemical and Biophysical Research Communications, 1977
Abstract The occurence of disialosyl (α-N-acetylneuraminyl-(2→8)-N-acetylneuraminyl) groups in gl... more Abstract The occurence of disialosyl (α-N-acetylneuraminyl-(2→8)-N-acetylneuraminyl) groups in glycoproteins was studied. It was found by methylation analysis that 8.5 % of N-acetylneuraminic acid in brain glycoproteins was substituted at C-8. The corresponding value was 16.6 % in brain gangliosides. The substituent was identified as neuraminic acid from its lability to neuraminidase treatment. The results demonstrate that not only gangliosides contain disialosyl groups, but these are also found in glycoproteins. The group is present in several types of carbohydrate units, with the highest proportion in N-glycosidic chains of large molecular size.
The derivatives obtained by permethylation of unsubstituted 2-amino-2-deoxy-hexitols and of these... more The derivatives obtained by permethylation of unsubstituted 2-amino-2-deoxy-hexitols and of these compounds monosubstituted at C-3, C-4, or C-6, and disubstituted at C-3 and C-6, have been analysed by g.l.c.-m.s. Each derivative can be identified on the basis of retention time and mass spectrum. In methylation analysis, methanolysis gave one derivative of each hexitol, whereas a mixture of products was formed when degradation was effected by acetolysis followed by hydrolysis. An application in the analysis of amino-sugar linkages in alkali-labile O-glycosylic oligosaccharides from rat-brain glycoproteins is described.
Uploads