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Development and Characterization of Branching Enzymes for Improving Industrial Starches

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dc.contributor.advisor Tetlow, Ian J.
dc.contributor.author White, Jessica Kristyn Victoria
dc.date.accessioned 2018-05-15T17:32:31Z
dc.date.available 2019-05-11T05:00:14Z
dc.date.copyright 2018-04
dc.date.created 2018-05-11
dc.date.issued 2018-05-15
dc.identifier.uri http://hdl.handle.net/10214/13052
dc.description.abstract Starch is a plant-based polyglucan made of branched amylopectin and linear amylose, and is used in many food and non-food applications. The linear component forms undesirable gels during industrial processing at temperatures below 100 degree Celsius. This thesis describes the development and characterization of branching enzymes with potential to minimize gelling by branching starch. Site-directed mutants of Deinococcus radiodurans glycogen branching enzyme (DrGBE) were made (Gln205His, Ala310Gln, Ala310Gly, Ala312Thr). Relative to wild-type, Ala312Thr exhibited increased activity with amylopectin and increased substrate-affinity for amylose and amylopectin, whereas the other mutants exhibited decreased activity with amylose and amylopectin, and Gln205His and Ala310Gln exhibited increased substrate-affinity for amylopectin. An attempt to study DrGBE activity with amylose and amylopectin within starch was unsuccessful, because changes in amylopectin masked changes in amylose. Unsuccessful attempts were made to improve activities of chimeric enzymes previously made with Zea mays and Thermus thermophilus branching enzyme domains by modifying protein expression/purification/refolding. en_US
dc.description.sponsorship This research was funded by the Ontario Ministry of Agriculture, Food and Rural Affairs. en_US
dc.language.iso en en_US
dc.rights Attribution-NonCommercial-NoDerivs 2.5 Canada *
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/2.5/ca/ *
dc.subject starch en_US
dc.subject branching enzyme en_US
dc.subject Deinococcus radiodurans en_US
dc.title Development and Characterization of Branching Enzymes for Improving Industrial Starches en_US
dc.type Thesis en_US
dc.degree.programme Molecular and Cellular Biology en_US
dc.degree.name Master of Science en_US
dc.degree.department Department of Molecular and Cellular Biology en_US
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Attribution-NonCommercial-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 2.5 Canada