Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes

 

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dc.contributor.advisor Stephen, A M en_ZA
dc.contributor.author Ravenscroft, Neil en_ZA
dc.date.accessioned 2016-02-22T07:20:45Z
dc.date.available 2016-02-22T07:20:45Z
dc.date.issued 1988 en_ZA
dc.identifier.citation Ravenscroft, N. 1988. Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/17186
dc.description Includes bibliographical references. en_ZA
dc.description.abstract As part of an international collaborative programme concerned with the elucidation of the molecular structures of capsular polysaccharides (the K-antigen) produced by strains of the bacterial genus Klebsiella, the capsular material of serotype K71 has been investigated, and that of serotypes K36 and K64 re-examined, by novel enzymic and spectroscopic methods. The cultivation and employment of bacteriophages which are capable of cleaving (by specific glycanase action) the isolated, cognate bacterial polysaccharide in vitro has yielded highly significant oligosaccharides. These may represent the repeating unit in the polysaccharide or be derivatives resulting from conversion of uronic acid to the 4,5-unsaturated analogue where, as found for serotype K64, the mode of cleavage is β-elimination not hydrolysis. The oligosaccharides thus generated have proved to be far more amenable to chemical and spectroscopic studies than their parent polymers, thereby facilitating complete characterisation of the molecular structures of the original polysaccharides. Chemical methods applied to these oligosaccharides included specific degradations by periodate oxidation and acid-, alkali- or enzyme- catalysed hydrolysis, products being identified by methylation analysis (involving the extensive use of gas-liquid chromatography coupled to mass spectrometry) and spectroscopic studies (mass and n.m.r.). During the course of these investigations it became apparent that the structures of the intact oligosaccharides (containing six or seven sugar residues) could be determined almost entirely from spectroscopic analysis, chiefly by detailed two-dimensional n.m.r. studies involving the use of high field spectrometers and the application of homo- and heteronuclear shift correlated spectroscopy, the sequence of sugar units being confirmed by mass spectrometric analysis of the permethylated derivatives. Methylation analysis of the oligosaccharides derived from Klebsiella serotype K36 proved that the glucuronic acid residue is linked through 0-2, and not 0-4 as published by others; this finding was corroborated during characterisation of the monomeric oligosaccharide by mass- and n.m.r. spectroscopy. Bacteriophage φ64 was shown to cleave the cognate K64 exopolysaccharide by a β-elimination process; the resulting hex-4-enuronic acid, present as a terminal group in the derived oligosaccharide was fully characterised by hydrogenation and g.l.c.-m.s. of acetylated products, and by detailed n.m.r. studies including long-range heteronuclear experiments. Finally the structure of the heptasaccharide repeating unit of the Klebsiella K71 capsular polysaccharide was established by spectroscopic analysis of the oligosaccharides derived by bacteriophage φ71 cleavage of the polymer; features of the proposed structure were confirmed by chemical degradation studies performed on the native polysaccharide. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Polysaccharides en_ZA
dc.subject.other Oligosaccharides en_ZA
dc.subject.other Enterobacteriaceae en_ZA
dc.subject.other Organic Chemistry en_ZA
dc.title Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes en_ZA
dc.type Doctoral Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Chemistry en_ZA
dc.type.qualificationlevel Doctoral
dc.type.qualificationname PhD en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Ravenscroft, N. (1988). <i>Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Chemistry. Retrieved from http://hdl.handle.net/11427/17186 en_ZA
dc.identifier.chicagocitation Ravenscroft, Neil. <i>"Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Chemistry, 1988. http://hdl.handle.net/11427/17186 en_ZA
dc.identifier.vancouvercitation Ravenscroft N. Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Chemistry, 1988 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/17186 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Ravenscroft, Neil AB - As part of an international collaborative programme concerned with the elucidation of the molecular structures of capsular polysaccharides (the K-antigen) produced by strains of the bacterial genus Klebsiella, the capsular material of serotype K71 has been investigated, and that of serotypes K36 and K64 re-examined, by novel enzymic and spectroscopic methods. The cultivation and employment of bacteriophages which are capable of cleaving (by specific glycanase action) the isolated, cognate bacterial polysaccharide in vitro has yielded highly significant oligosaccharides. These may represent the repeating unit in the polysaccharide or be derivatives resulting from conversion of uronic acid to the 4,5-unsaturated analogue where, as found for serotype K64, the mode of cleavage is β-elimination not hydrolysis. The oligosaccharides thus generated have proved to be far more amenable to chemical and spectroscopic studies than their parent polymers, thereby facilitating complete characterisation of the molecular structures of the original polysaccharides. Chemical methods applied to these oligosaccharides included specific degradations by periodate oxidation and acid-, alkali- or enzyme- catalysed hydrolysis, products being identified by methylation analysis (involving the extensive use of gas-liquid chromatography coupled to mass spectrometry) and spectroscopic studies (mass and n.m.r.). During the course of these investigations it became apparent that the structures of the intact oligosaccharides (containing six or seven sugar residues) could be determined almost entirely from spectroscopic analysis, chiefly by detailed two-dimensional n.m.r. studies involving the use of high field spectrometers and the application of homo- and heteronuclear shift correlated spectroscopy, the sequence of sugar units being confirmed by mass spectrometric analysis of the permethylated derivatives. Methylation analysis of the oligosaccharides derived from Klebsiella serotype K36 proved that the glucuronic acid residue is linked through 0-2, and not 0-4 as published by others; this finding was corroborated during characterisation of the monomeric oligosaccharide by mass- and n.m.r. spectroscopy. Bacteriophage φ64 was shown to cleave the cognate K64 exopolysaccharide by a β-elimination process; the resulting hex-4-enuronic acid, present as a terminal group in the derived oligosaccharide was fully characterised by hydrogenation and g.l.c.-m.s. of acetylated products, and by detailed n.m.r. studies including long-range heteronuclear experiments. Finally the structure of the heptasaccharide repeating unit of the Klebsiella K71 capsular polysaccharide was established by spectroscopic analysis of the oligosaccharides derived by bacteriophage φ71 cleavage of the polymer; features of the proposed structure were confirmed by chemical degradation studies performed on the native polysaccharide. DA - 1988 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1988 T1 - Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes TI - Chemical and spectroscopic studies of the capsular polysaccharides of some Klebsiella serotypes UR - http://hdl.handle.net/11427/17186 ER - en_ZA


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