Drugs that are preferentially absorbed through the stomach or the small intestine have a narrow time window for absorption since passage through this region of the gastrointestinal tract is rapid. A drug delivery system that can adhere to the gastric epithelium will substantially slow down drug transit and help overcome this problem. To achieve this, this study proposes the novel use of a glycan-binding adhesion protein from Helicobacter pylori, BabA, to create targeted drug delivery vectors that can mimic the attachment of this bacterium to the gastric epithelium. In this work, a recombinant form of BabA was expressed in the periplasmic space of Escherichia coli; it was found that after the incorporation of a C-terminal hexa-lysine tag, the expression and purification of this protein was significantly improved to amounts that enabled its subsequent characterisation and application. Recombinant BabA retained the highly selective glycan-binding properties of H. pylori and next, its crystal structure was solved in the absence and presence of Lewisb – a glycan well studied for its role in serving as a receptor for BabA. The structural models revealed that Lewisb binding occurred through a network of hydrogen bonds within a single, shallow binding pocket at the tip of a β-unit in BabA. Binding studies then confirmed that this site was also responsible for the recognition of other glycan receptors. Using this insight, recombinant BabA was conjugated to model drug delivery vectors via a linkage that favoured exposure of its glycan-binding β-unit; the binding properties of BabA successfully translated to these model BabA-vectors. The research presented in this thesis lays a strong foundation for future work to assess the in vitro and in vivo efficacy of biomimetic BabA drug carriers.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:689784 |
| Date | January 2016 |
| Creators | Hage, N. |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/32134/ |
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