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Complete structure of the polysaccharide from Streptococcus sanguis J22
C Abeygunawardana1, C A Bush, J O Cisar
1Department of Chemistry, Illinois Institute of Technology, Chicago 60616.
Biochemistry
|January 9, 1990
Summary
The cell wall structure of Streptococcus sanguis J22 was elucidated using advanced NMR methods. This research details the heptasaccharide subunit and phosphodiester linkages, aiding in understanding oral streptococcal interactions.
Area of Science:
- Carbohydrate Chemistry
- Microbial Cell Wall Structure
- Structural Biology
Background:
- Oral streptococci cell wall polysaccharides serve as receptors for Actinomyces viscosus lectins.
- Immunologically distinct polysaccharides from S. sanguis strains 34 and J22 interact with A. viscosus.
Purpose of the Study:
- To determine the complete covalent structure of the polysaccharide from Streptococcus sanguis J22.
- To compare the S. sanguis J22 polysaccharide structure with that of S. sanguis strain 34.
Main Methods:
- High-resolution nuclear magnetic resonance (NMR) spectroscopy was the primary method.
- Complete assignment of 1H and 13C NMR spectra for both strains.
- Utilized COSY, HMQC, and HMBC experiments for structural elucidation.
Main Results:
- The S. sanguis J22 polysaccharide is composed of a repeating heptasaccharide subunit linked by phosphodiester bonds.
- The subunit contains specific alpha and beta glycosides of N-acetylgalactosamine, rhamnose, glucose, and galactose (including beta-galactofuranose).
- Detailed assignments confirmed stereochemistry, glycosidic linkages, and phosphodiester linkage positions.
Conclusions:
- The complete covalent structure of the S. sanguis J22 cell wall polysaccharide has been determined.
- Structural comparison with S. sanguis strain 34 provides insights into receptor-lectin interactions in the oral microbiome.
- Advanced NMR techniques were crucial for this detailed structural analysis.