Structural Studies of Some Bacterial Polysaccharides and Synthesized Model Trisaccharides

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Adeyeye, A. A.
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University of Lagos
This thesis reports the structures of five bacterial antigens as well as the syntheses of four model oligosaccharides. The bacterial antigens investigated are the lipopolysaccharides (LPS) isolated from Brucella abortus strain 7 Mustapha, Campylobacter coli Labet 227, Escherichia coli 0149 and the capsular polysaccharide from Streptococcus pneumonia type 37. The techniques of the investigation were sugar analysis, methylation analysis, specific degradation studies and n.m.r. spectroscopy. The polysaccharide from Brucella abortus (B.abortus was found to be homopolymers of 1,2-linked 4-formamido-4, 6-dideoxy-&-D-mannopyranosyl units. Campylobacter coli Label 27 was found to synthesize only the core. Two oligosaccharides labelled OS (I) and (OS II) glucose, galactose, 2-acetamido-2-deoxyglucose, 2-acetamido-2-deoxy-galactose and very small quantities of heptose.The O-antigen polysaccharide from Escherichia coli 0149 was composed of trisaccharide repeating units having the structure A.1. ->4)-B-D-GlcpNac-(1->3)-2-D-GlcpNAC-(1->3)-B-L-Rhap-(1->/ \4 6\ /C/ \H3C COOH A.1.The capsular polysaccharide elaborated by Streptococcus pneumonia type 37 was found to consist of disaccharide repeating units having the structure A.2.->3)-B-D-Glcp(1-2llB-D-Glcp A.2 Four model trisaccharides were synthesized for structural and conformational studies are listed (a) to (d).a. &-D-Glucose-(1->2)-&-D-Glucose-(1->3)-&-D-Glucose1->OMe b. &-D-Glucose-(1-2)-&-D-Glucose-(1->3)-&-D-Glucose1->OMe c. B-D-Glucose-(1-2)-&-D-Glucose-(1 ->3)-&-D-Glucose1->OMe d. B-D-Glucose-(1->)-a-D-Glucose-(1->3)-a-D-Glucose1->OMe Extensive conformational analysis studies on the trisaccharides are reported using the HSEA calculation techniques. The n.m.r. and conformational studies showed that the changes in the glycosidation shifts from the n.m.r. spectra of disaccharides can be used for those of related trisaccharides with the additivity of the glycosylation shifts of the 1-->2 and 1->3 disaccharide units taken into consideration.
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Bacterial Polysaccharides , Trisaccharides
Adeyeye, A. A. (1988), Structural Studies of Some Bacterial Polysaccharides and Synthesized Model Trisaccharides. University of Lagos School of Postgraduate Studies Phd Thesis and Dissertation Abstracts