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Start Over Author "Abhijit Roy" Journal carbohydrate research
4 results on '"Abhijit Roy"'

1. 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

Author

Abhijit Roy, Nirmolendu Roy, Asim K. Ray, and Usha B. Maddali

Subjects
Stereochemistry, Molecular Sequence Data, Disaccharide, Polysaccharide, medicine.disease_cause, Disaccharides, Biochemistry, Analytical Chemistry, Antigen-Antibody Reactions, chemistry.chemical_compound, Antigen, Streptococcus pneumoniae, medicine, Side chain, Trisaccharide, chemistry.chemical_classification, Organic Chemistry, Polysaccharides, Bacterial, Glycoside, General Medicine, Precipitin Tests, chemistry, Carbohydrate Sequence, Epimer, Trisaccharides
Abstract

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.

Published
1990

2. Structure of the capsular polysaccharide of Klebsiella serotype K40

Author

Abhijit Roy, Nirmolendu Roy, and Asim K. Ray

Subjects
Klebsiella, Optical Rotation, Rhamnose, Stereochemistry, Mannose, Polysaccharide, Biochemistry, Analytical Chemistry, chemistry.chemical_compound, Residue (chemistry), Carbohydrate Conformation, Organic chemistry, Serotyping, chemistry.chemical_classification, biology, Hydrolysis, Polysaccharides, Bacterial, Organic Chemistry, Glycosidic bond, General Medicine, biology.organism_classification, Glucuronic acid, Carbohydrate Sequence, chemistry, Galactose
Abstract

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)

Published
1987
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3. Structure of the capsular polysaccharide from Streptococcus pneumoniae type 23

Author

Abhijit Roy and Nirmolendu Roy

Subjects
chemistry.chemical_classification, Chromium trioxide, Optical Rotation, Organic Chemistry, Polysaccharides, Bacterial, Sequence (biology), General Medicine, Methylation, medicine.disease_cause, Polysaccharide, Biochemistry, Analytical Chemistry, chemistry.chemical_compound, Streptococcus pneumoniae, chemistry, Carbohydrate Sequence, Glycerol, medicine, Carbohydrate Conformation, Carbohydrate conformation, Sugar, Oxidation-Reduction
Abstract

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)

Published
1984

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