A UCL Some Studies of Artificial Enzyme Systems

This thesis describes a novel approach to the rational design o f artificial esterases and aldolases. The Introduction provides a literature summary of the previous approaches that have been employed towards the design and synthesis of artificial enzyme systems. Chapter 2 describes the preparation and reactivity of a number of polymer based artificial enzymes, which are capable of catalysing ester hydrolysis. The study has involved the incorporation of a histidine catalytic group together with specifically designed peptide binding groups within a polymeric backbone. The binding groups were specifically selected according to their binding affinity towards an appropriate transition state analogue. The synthesis of peptide binding sites and thus incorporation of these, together with the histidine catalytic group into a polymer backbone, using standard peptide chemistry has been outlined. The results to an investigation of the influence of different pH, solvent and substrate concentration on the activity of artificial esterases are presented. Chapter 3 describes preliminary work undertaken towards the design and synthesis of artificial aldol catalysts. The aldolases, which feature a proline residue attached to a polymer backbone are shown to selectively catalyse aldol reactions using aromatic aldehydes as electrophilic partner. Chapter 4 describes the detailed experimental procedures used.