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Structural elucidation of the capsular polysaccharide from Streptococcus pneumoniae type 18B
C Karlsson1, P E Jansson, G Widmalm
1Clinical Research Center, Karolinska Institute, Huddinge Hospital, Sweden.
Carbohydrate Research
|February 5, 1998
Summary
The capsular polysaccharide structure of Streptococcus pneumoniae type 18B was elucidated. It features pentasaccharide repeating units with a glycerol phosphate substituent, differing from type 18F by lacking O-acetyl groups.
Area of Science:
- Carbohydrate Chemistry
- Microbial Biochemistry
- Structural Biology
Background:
- Streptococcus pneumoniae possesses diverse capsular polysaccharides crucial for its virulence and serotyping.
- Understanding the precise structure of these polysaccharides is essential for vaccine development and diagnostics.
Purpose of the Study:
- To determine the detailed chemical structure of the capsular polysaccharide from Streptococcus pneumoniae type 18B.
- To compare the structure with related serotypes, such as 18F and 18A.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy for detailed structural analysis.
- Methylation analysis to identify glycosidic linkages and substitution patterns.
Main Results:
- The polysaccharide is composed of pentasaccharide repeating units.
- A glycerol phosphate moiety substitutes the 3-position of the branch point residue.
- The carbohydrate backbone is identical to S. pneumoniae type 18F, but lacks O-acetyl groups.
Conclusions:
- The complete structure of Streptococcus pneumoniae type 18B capsular polysaccharide has been established.
- The presence and position of the glycerol phosphate group are key structural features.
- Structural similarities and differences with other serotypes provide insights into their antigenic properties.