Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Mary J. Wirth, Dept. of Chemistry and Biochemistry. Includes bibliographical references.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 4 uppsatser.

Thèse de doctorat--Sciences naturelles--Faculté des sciences de Paris, 1900. N°: 1030.

The partially acetylated acidic mucilage isolated from the cactus Opuntia ficus-indica consists of a highly branched molecule containing D-galactose, L-arabinose, D-xylose, D-galacturonic acid and L-rhamnose in the ratio 2.9:6.6:3.8:1.3 : 1.0. A partial hydrolysis study led to the isolation of fourteen oligosaccharides and a degraded polysaccharide. Periodate oxidation of the degraded polysaccharide and methylation analysis of the degraded and reduced degraded polysaccharides led to the proposal of a structure for the degraded polysaccharide consisting of a chain of alternating α-l,4-D-galactopyranosyluronic acid and β-1,2-Lrhamnopyranosyl units with branches consisting of short chains of β-1,6-D-galactopyranosyl units Iinked to C-3 of the rhamnose residues. An insight into the nature of the peripheral side-chains was obtained by methylation studies of the oligosaccharides and the native polysaccharide. The majority of the side-chains are terminated by D-xylopyranosyl and L-arabinofuranosyl units while there is a small proportion of D-galactopyranosyl end-groups. The remaining units of the peripheral chains consists of mainly 1,3- and 1,5-1 inked L-arabinofuranosyl units. The acidic polysaccharide isolated from the jointed cactus Opuntia aurantiaca contains D-galactose, L-arabinose, D-xylose, D-galacturonic acid and L-rhamnose in the ratio 5.9:5 .5:3.4: 1. 2:1.0 . A partial hydrolysis study revealed a similar series of galactose containing oligosaccharides as was identified from the mucilage of Opuntia ficus-indica. The degraded polysaccharide isolated from the partial hydrolysate was methylated and a possible structure proposed for the repeating unit. Methylation studies of the native polysaccharide indicated a polysaccharide with a more complex structure than that for the mucilage of Opuntia ficus-indica.

Mesquite gum, sapote gum A and sapote gum B have been subjected to purification and hydrolysis. Chromatographic examination of each hydrolysate has revealed the constituent sugars. The three gums have been methylated and chromatographic examination of hydrolysates from these methylated derivatives has indicated the methylated sugars present. Methylated mesquite gum yielded 2,3,5-trimethyl-L-arabinose, 3,5-dimethyl-L-arabinose, 2,4-dimethyl-D-galactose and 2,3,4-trimethyl-D glucuronic acid. Sapote gum A gave 2,3,4-trimethyl-D-xylose, 2,3,4-trimethyl-L-arabinose, 3-monomethyl-D-xylose and some 2,3,4-trimethyl-D-glucuronic acid. These results are in agreement with published data. A second sample of sapote gum, designated as sapote gum B, has been shown to contain different methylated sugars. Both gums were obtained from the same source. Among the components of sapote gum B 2,3,4-trimethyl rhamnose, 2, 3,5-trimethyl arabinose and 2,3,4-trimethyl xylose have been detected. The presence of 2,4-dimethyl-D-galactose, 2,3,4-trimethyl-D-galactose and 2,3,4-trimethyl-D-glucuronic acid has also been shown. The difference in the methylated products obtained from the two samples of sapote gum indicates a dissimilarity of structure. Both gums were thought to be produced by the same species, but in view of the above results this does not appear likely. / Science, Faculty of / Chemistry, Department of / Graduate

A gas chromatographic method has been developed whereby the following compounds may be determined quantitatively and simultaneously: ethylene glycol, glycerol, erythritol, threitol, arabinose, xylose, mannose, galactose and glucose. These products correspond to the constituent parts of periodate oxidized, borohydride reduced polysaccharides. Quantitative analysis of the fractions obtained on total and partial hydrolysis of such polyalcohols provides a new and powerful analytical tool in polysaccharide chemistry. Optimum conditions for the Smith degradation of a polysaccharide have been illustrated by a detailed analysis of lemon gum. A new method for the reduction of uronic acids in poly- and oligosaccharides has been developed. Reduction can be carried out after only esterification of the uronic acids. Reaction at this stage avoids possible degradation or fractionation during esterification and subsequent saponification of polysaccharide hydroxyl groups. Good levels of reduction [75%] have been achieved with reduction of highly branched lemon gum. Silylated polyhydroxy compounds and galacturonic acid were examined by proton magnetic resonance spectroscopy. The trimethylsilyl [TMS] protons of such ethers and esters show good separation from one another. Analysis of the trimethylsilyl proton peaks provides information concerning the number and degree of subsitution of hydroxyl and acid functions present in the parent molecule. Signal strength due to the nine protons on each trimethylsilyl group provides a chemical means of signal enhancement. Analysis was carried out on 2 mg. of a minor TMS glucofuranose derivative. Lemon gum has been analysed by the method of Lindberg et al [8l]. Analysis of lemon gum is the first example of the application of partially methylated alditol acetate mass spectroscopy to a plant gum. The results of this analysis are in good agreement with previous analysis of this gum. / Science, Faculty of / Chemistry, Department of / Graduate

The genus KIebsiella is divisible into approximately eighty different strains characterized on the basis of immunochemical tests. These Gram-negative bacteria produce large capsular polysaccharides which are their antigenic determinants. In order to understand the chemical basis of serological differentiation, the structural investigation of all 80 strains is taking place. Until now about fifty structures have been elucidated. The capsular antigens isolated from Klebsiella serotypes K53 and K74 are presented here and were determined using many different techniques. Methylation analysis, partial hydrolysis, and uronic acid degradation were used to study the sequential arrangement of the sugar constituents in the polysaccharide. Extensive use was made of ¹H-and ¹³C-nuclear magnetic resonance spectroscopy to determine anomeric linkages within isolated oligosaccharides and the native polysaccharide. Methods such as gas liquid chromatography, gas liquid chromatography - mass spectrometry, paper chromatography, and polarimetry have been used to isolate and characterize products obtained from different degradative techniques. The capsular polysaccharides from Klebsiella serotypes K53 and K74 are found to consist of repeating units of the following structures: [diagram omitted]. / Science, Faculty of / Chemistry, Department of / Graduate

To date, studies have revealed that seventy-eight serologically distinct strains of Klebsiella bacteria exist. The antigenic character of each strain in an immunological reaction is considered to be determined by the capsular polysaccharide which surrounds the bacterial cell. Structures of the capsular polysaccharides from well over half the known Klebsiella strains have been established; all of them unique. In a continuing program to elucidate the chemical structures of these polysaccharides in order to explain immunological responses, evidence for the structure of the antigens from Klebsiella serotypes K17 and K44 is presented. Methylation analysis was used to establish linkage positions of the monosaccharide units. Uronic acid degradation, periodate oxidation-Smith degradation, and partial hydrolysis were the techniques employed to generate and study oligosaccharides from the more complex polymer. Extensive use was made of ¹H and ¹³C nuclear magnetic resonance spectroscopy to indicate anomeric configurations of the oligo- and polysaccharides alike. Methods such as gas liquid chromatography, gas liquid chromatography-mass spectrometry, gel filtration chromatography, paper chromatography, and polarimetry have been used to isolate and identify the products obtained from the various degradative techniques. Although the polysaccharides of K-types 17 and 44 are part of a small group with the same qualitative composition, their structures are found to consist of the following dissimilar repeating units: [2 diagrams of chemical structures] The latter represents pentasaccharide repeating saccharide. the first unit in a example of Klebsiella a linear capsular poly-saccharide. / Science, Faculty of / Chemistry, Department of / Graduate

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thèse de doctorat : Géosciences : INPL : 2008. / Titre provenant de l'écran-titre.