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N Roy

Publications and source records attributed to N Roy.

At least 91 records · Page 5Linked to original sources
PubMed1990

Synthesis of di- and tri-saccharides related to the polysaccharide from Streptococcus pneumoniae type 23 and a study of their inhibition in the precipitin reaction.

Syntheses of methyl 2-O-beta-L-rhamnopyranosyl-beta-D-galactopyranoside (9), methyl 2-O-alpha-L-rhamnopyranosyl-beta-D-galactopyranoside (13), and methyl 4-O-beta-D-glucopyranosyl-2-O-alpha-L-rhamnopyranosyl-beta-D- galactopyranoside (16) in good yields are described. Both 13 and 16 significantly inhibit antigen-antibody precipitation in the S. pneumoniae Type 23 immune system. The results indicate that the rhamnosyl group in the side chain of the repeating unit of the antigen is alpha and not beta as reported previously, and that the trisaccharide related to 16 is the immunodominant group.

Antigen-Antibody Reactions↗
PubMed1990

Synthesis of the tetrasaccharide repeating-unit of the polysaccharide from Klebsiella type 23.

Methyl 2-O-allyl-4-O-benzyl-3-O-(2,3,4,6-tetra-O-acetyl-beta-D- glucopyranosyl)-alpha-L-rhamnospyranoside was obtained by condensing methyl 2-O-allyl-4-O-benzyl-alpha-L-rhamnopyranoside with tetra-O-acetyl-alpha-D-glucopyranosyl bromide. Benzylation, removal of the allyl group, and condensation of the product with ethyl 6-O-acetyl-2,3,4-tri-O-benzyl-1-thio-beta-D-glucopyranoside gave methyl 2-O-(6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl)-4-O-benzyl-3- O- (2,3,4,6-tetra-O-benzyl-beta-D-glucopyranosyl)-alpha-L-rhamnopyranoside. O-Deacetylation, condensation of the product with methyl (2,3,4-tri-O-acetyl-alpha-D-glucopyranosyl bromide)-uronate, and removal of the protecting groups gave methyl 3-O-beta-D-glucopyranosyl-2-O-[6-O-(beta-D-glucopyranosyluronic acid)-alpha-D-glucopyranosyl]-alpha-L-rhamnopyranoside (13).

Carbohydrate Sequence↗
PubMed1990

Characterization of anti-sticking factor-II from goat epididymal plasma.

A previous study has characterized the major 47 kDa anti-sticking factor (ASF-I) from goat cauda-epididymal plasma (Roy, N., and Majumder, G.C., Biochim. Biophys. Acta, 991:114-122, 1989). This study reports the purification and characterization of ASF-II, another anti-sticking factor from the goat epididymal plasma. ASF-II was purified to apparent homogeneity by using concanavalin A-agarose affinity chromatography, DEAE-cellulose chromatography, alumina gel adsorption, and isoelectric focussing techniques. It showed a single protein band by both non-denaturing and SDS-polyacrylamide gel electrophoresis. ASF-II showed a molecular weight of 36,000 and a sedimentation constant of 2.4S. ASF-II is largely stable to heat treatment and it is a specific glycoprotein having high affinity and specificity for its anti-sticking action. At saturating concentration (1 nM) it inhibited adhesion of nearly 50% of spermatozoa to the glass surface of the haemocytometer counting chamber. Both the protein and sugar parts of the factor are essential for the anti-sticking activity since it lost its activity completely when treated with trypsin, L-fucosidase, or mannosidase. ASF-II does not coat the glass surface and it binds to spermatozoa. Data are consistent with the view that ASF-II has not been derived from the larger ASF-I molecule due to its enzymic modifications. Both ASF-I and -II had no effect on sperm forward motility as evidenced by spectrophotometric motility assays, indicating thereby the suitability of the factors to improve the existing sperm motility assays by eliminating the possibility of cell-sticking artifacts.

Adsorption↗
PubMed1989

Synthesis of a di- and a tri-saccharide related to the K-antigen of Klebsiella type 10 and a study of their inhibition in the precipitin reaction.

Syntheses of methyl 3-O-alpha-D-galactopyranosyl-alpha-D-mannopyranoside (10) and methyl 3-O-alpha-D-galactopyranosyl-2-O-(beta-D-glucopyranosyluronic acid)-alpha-D-mannopyranoside (11) in good yield are described. Both 10 and 11 significantly inhibit antigen-antibody precipitation in the Klebsiella Type 10 immune system. The results provide more evidence for the structure (1) of the antigen from Klebsiella K-10 and its immunodominant grouping.

Antigens, Bacterial↗
PubMed1989

Purification and characterization of an anti-sticking factor from goat epididymal plasma that inhibits sperm--glass and sperm--sperm adhesions.

An anti-sticking factor (ASF-I) that showed high affinity for inhibiting adhesion of spermatozoa to glass was isolated from goat epididymal plasma and characterized. The factor was purified approx. 5600-fold and showed a single protein band when examined by non-denaturation and SDS-polyacrylamide gel electrophoresis. The molecular mass and S20w value of ASF-I were approx. 47 kDa and 4.25 S. ASF-I at a concentration of 1 nM showed nearly maximal anti-sticking activity when approx. 60% of the intact spermatozoa were prevented from adhesion to glass and it showed a high degree of protein specificity. Studies with trypsin and glycosidases demonstrated that both the sugar and protein parts of the molecule are essential for its anti-sticking activity. Evidence has been presented to support the view that the outer surface of sperm possesses specific ASF-I receptors that bind to 125I-labelled ASF and mediate cell adhesion to glass. ASF-I also showed high affinity for inhibiting agglutination of corpus-epididymal spermatozoa. The ASF activity was found to be distributed in all the tissues tested and its specific activity was markedly higher in blood plasma than in the tissues. The results suggest that ASF may play an important biological role by serving as a specific inhibitor of cell-substratum and cell-cell adhesions.

Animals↗
PubMed1987

Structure of the capsular polysaccharide of Klebsiella serotype K40.

The capsular polysaccharide from Klebsiella Serotype K40 contains D-galactose, D-mannose, L-rhamnose, and D-glucuronic acid in the ratios of 4:1:1:1. Methylation analysis of the native and carboxyl-reduced polysaccharide provided information about the glycosidic linkages in the repeating unit. Degradation of the permethylated polymer with base established the identity of the sugar unit preceding the glycosyluronic acid residue. The modes of linkages of different sugar residues were further confirmed by Smith degradation and partial hydrolysis of the K40 polysaccharide. The anomeric configurations of the different sugar residues were determined by oxidation of the peracetylated native and carboxyl-reduced polysaccharide with chromium trioxide. Based on all of these results, the heptasaccharide structure 1 was assigned to the repeating unit of the K40 polysaccharide. (Formula: see text)

Carbohydrate Conformation↗
PubMed1986

Structure of the Klebsiella type 10 capsular polysaccharide.

The capsular polysaccharide from Klebsiella Type 10 was found to contain D-galactose, D-glucose, D-mannose, and D-glucuronic acid in the ratios 3:1:1:1. Acid hydrolysis of the polysaccharide gave one aldobiouronic acid, one aldotriouronic acid, one aldotetraouronic acid, and two neutral disaccharides the structures of which were established. The native and carboxyl-reduced polysaccharide have been subjected as appropriate to methylation analysis and Smith degradation. Degradation of the methylated polysaccharide with base established the identity of the sugar unit preceding the glucosyluronic acid residue. The anomeric configurations of the sugar residues were determined by oxidation of the acetylated native and carboxyl-reduced polysaccharides with chromium trioxide. Based on these studies, the hexasaccharide structure 1 has been assigned to the repeating unit of the K-10 polysaccharide.

Bacterial Capsules↗
PubMed1986

A simple quantitative method for the estimation of free ecto-sulfhydryl groups of spermatozoa.

A simple rapid quantitative method has been developed for the estimation of sperm ecto-SH groups on the basis of their high affinity binding to the mercurial: [203Hg]p-chloromercuriphenylsulfonic acid (PCMPS) used as a surface probe. The thiol reagent did not penetrate the sperm plasma membrane, as evidenced by the extremely rapid time course of the binding reaction and undetectable uptake of [203Hg]PCMPS by intact goat spermatozoa. The binding reaction was not due to contaminating broken or damaged cells, if any. The method consists of incubating of highly motile goat spermatozoa with PCMPS in a modified Ringer solution at 37 degrees C for 5 min, agglutination of the labelled cells with polyethyleneimine (100 micrograms/ml) and filtration and washing of the cell suspension through Whatman No. 1 filter discs under mild vacuum. The binding interaction is proportional to cell concentration, specific and saturable at 50 microM PCMPS. The method is capable of estimating free ecto-SH as low as 25 pmoles. Spermatozoa possess 286 +/- 61 pmoles of free ecto-SH groups/10(6) cells. Scatchard analysis showed the presence in goat spermatozoa of multiple classes of ecto-SH groups differing in their affinity for PCMPS.

4-Chloromercuribenzenesulfonate↗
PubMed1984

Structure of the capsular polysaccharide from Streptococcus pneumoniae type 23.

The capsular polysaccharide from Streptococcus pneumoniae Type 23 (S-23) was found to contain D-galactose, D-glucose, L-rhamnose, glycerol, and phosphorus in the ratios of 1:1:2:0.6:1. Methylation analysis provided information about the linkages of the different sugar units. The sequence of the different sugar residues was confirmed by Smith degradation. Oxidation of S-23 with chromium trioxide indicated that all of the sugar units have the beta configuration. The results suggest the following structure for the repeating unit. (formula; see text)

Carbohydrate Conformation↗
PubMed1981

Structure of the capsular polysaccharide of Klebsiella type 73 (Enterobacter aerogenes).

The capsular polysaccharide from Klebsiella Type 73 (Enterobacter aerogenes) was found to contain equimolar amounts of D-galactose, D-glucose, L-rhamnose, and D-glucuronic acid. Acid hydrolysis of the polysaccharide gave one aldobio-and one aldotrio-uronic acid, whose structures were established by acid hydrolysis and by methylation analysis. The anomeric configurations of the different sugar residues were determined from the specific rotations of the polysaccharide and the aldobio-and aldotrio-uronic acids, and also by oxidation of the native and the carboxyl-reduced polysaccharide with chromium trioxide. Methylation analysis of the polysaccharide provided information about the linkages of the different sugar residues. Based on all of these results, the structure assigned to the repeating unit of the polysaccharide is as follows. (Formula: see text).

Carbohydrate Conformation↗