Carbohydrate-based interactions at the molecular and the cellular level

• Main Author: Hudson, Kieran L.
• Published: University of Bristol 2016
• Subjects: 547
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.691245

Many of the roles of carbohydrates in biology derive from their interaction with proteins, through which they effect intra- and intercellular signalling and the modulation of the structure and activity of proteins. Understanding proteincarbohydrate interactions in atomistic detail is essential to allow the manipulation and exploitation of these processes. The first part of this thesis utilises the many published protein X-ray crystal structures that contain carbohydrates. A database of protein- carbohydrate interactions was generated to elucidate the nature of carbohydrate-based interactions at the atomistic and molecular levels. The particular focus is on the carbohydrate-aromatic interaction, involving the positioning of aromatic aminoacid side chains over carbohydrate C-H bonds. This reveals an important role for electrostatics in carbohydrate-aromatic interactions, and in CH-1[ interactions in general, which is distinct from the hydrophobic effect. These findings are supported by solution-phase studies of carbohydrate-aromatic interactions by NMR spectroscopy. The second part describes the development of carbohydrates as tools for tissue engineering, given the recognised importance of carbohydrates in both signalling and structural roles in biology. The nature of the scaffold upon which artificial tissues are grown is of great importance, as the cellular environment influences development through its physical properties and the presence of biological cues. Carbohydrates are a promising and largely under-exploited class of biomolecules with the potential to modulate material properties and stimulate biological responses. A modifiable derivative of a system based upon complementary synthetic peptides that self-assemble into hydrogels was used as the core scaffold. This was functionalisable with biological cues via copper I click' chemistry. Alkynyl monosaccharides were synthesised and used to verify the applicability of carbohydrates as modifiers, both in terms of maintaining the key properties of the hydrogel and providing an appropriate support for cell culture. Enzymatic techniques enabled synthesis of complex alkyne-functionalised oligosaccharides chosen to be applicable to neural tissue engineering.