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Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta
The structures of the polysaccharide gum exudates from Brabeium stellatifolium and Grevillea robusta, both belonging to the family Proteaceae, have been investigated and compared. A general similarity between these two polysaccharide gums, both of high molecular weight, was apparent, although techni...
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| Format: | Thesis |
| Language: | English |
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Department of Chemistry
2023
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| _version_ | 1867613286023823360 |
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| access_status_str | Open Access |
| author | Van der Bijl, Pieter |
| author2 | Stephen, A M |
| author_browse | Stephen, A M Van der Bijl, Pieter |
| author_facet | Stephen, A M Van der Bijl, Pieter |
| author_sort | Van der Bijl, Pieter |
| collection | Thesis |
| description | The structures of the polysaccharide gum exudates from Brabeium stellatifolium and Grevillea robusta, both belonging to the family Proteaceae, have been investigated and compared. A general similarity between these two polysaccharide gums, both of high molecular weight, was apparent, although techniques such as methylation analysis, Smith-degradation and partial acid hydrolysis revealed small differences in fine structure. Brabeium stellatifolium gum was examined in somewhat more detail. In a study of hydrolysis of the gum by acid the degradation process was followed by gel chromatography. The elution curves obtained at different stages of hydrolysis demonstrated the production of fragments of preferred molecular size, and permitted analysis of the degradation pattern in terms of the fission of peripheral and of internal linkages. Hydrolysis of methylated Brabeium stellatifolium g·um, followed by separation of the resulting methyl ethers on a cellulose column, gave results in good agreement with those obtained on semi-quantitative GLC analysis of the methanolysate of the methylated gum. In Smith-degradation studies of both Brabeium stellatifolium and Grevillea robusta gums the conditions generally used for mild acid hydrolysis of the reduced, oxidised polysaccharides were modified to ensure complete cleavage of acetal linkages. Both gums yielded Smithdegradation products exhibiting a high degree of polyrnolecularity. The relative decreases in weight - average molecular weight M w, accompanying successive Smith-¬ degradations were similar for the two gums, A further point of resemblance was the unusual resistance to periodate oxidation of D-mannose and uronic acid residues in both gums. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/38917 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:43.673Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Department of Chemistry |
| publisherStr | Department of Chemistry |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/38917 Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta Van der Bijl, Pieter Stephen, A M Chemistry The structures of the polysaccharide gum exudates from Brabeium stellatifolium and Grevillea robusta, both belonging to the family Proteaceae, have been investigated and compared. A general similarity between these two polysaccharide gums, both of high molecular weight, was apparent, although techniques such as methylation analysis, Smith-degradation and partial acid hydrolysis revealed small differences in fine structure. Brabeium stellatifolium gum was examined in somewhat more detail. In a study of hydrolysis of the gum by acid the degradation process was followed by gel chromatography. The elution curves obtained at different stages of hydrolysis demonstrated the production of fragments of preferred molecular size, and permitted analysis of the degradation pattern in terms of the fission of peripheral and of internal linkages. Hydrolysis of methylated Brabeium stellatifolium g·um, followed by separation of the resulting methyl ethers on a cellulose column, gave results in good agreement with those obtained on semi-quantitative GLC analysis of the methanolysate of the methylated gum. In Smith-degradation studies of both Brabeium stellatifolium and Grevillea robusta gums the conditions generally used for mild acid hydrolysis of the reduced, oxidised polysaccharides were modified to ensure complete cleavage of acetal linkages. Both gums yielded Smithdegradation products exhibiting a high degree of polyrnolecularity. The relative decreases in weight - average molecular weight M w, accompanying successive Smith-¬ degradations were similar for the two gums, A further point of resemblance was the unusual resistance to periodate oxidation of D-mannose and uronic acid residues in both gums. 2023-09-27T16:46:00Z 2023-09-27T16:46:00Z 1971 2023-09-27T16:45:43Z Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/38917 eng application/pdf Department of Chemistry Faculty of Science |
| spellingShingle | Chemistry Van der Bijl, Pieter Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta |
| thesis_degree_str | Doctoral |
| title | Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta |
| title_full | Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta |
| title_fullStr | Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta |
| title_full_unstemmed | Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta |
| title_short | Structural investigations of the polysaccharide gum exudates from Brabeiurn Stellatifoliurn and Grevillea Robusta |
| title_sort | structural investigations of the polysaccharide gum exudates from brabeiurn stellatifoliurn and grevillea robusta |
| topic | Chemistry |
| url | http://hdl.handle.net/11427/38917 |
| work_keys_str_mv | AT vanderbijlpieter structuralinvestigationsofthepolysaccharidegumexudatesfrombrabeiurnstellatifoliurnandgrevillearobusta |