New Synthetic Technologies for Accessing Modified Peptides and Proteins

Abstract

Synthetic technologies developed to date have provided practitioners with the tools to assemble and study a structurally and functionally diverse selection of proteinaceous structures, including those that have come to prominence as game-changing therapeutics. Yet, the staggering array of native posttranslational modifications (PTMs), the complexity of their downstream functional impacts, and ongoing interest in new-to-nature modifications mean that many questions remain unanswered. Innovative strategies for accessing modified peptides and proteins and studying the relationship between their structure and function therefore remain in high demand and are needed to help unlock the secrets of the PTM-code and realise the full potential of the modified proteome. This thesis describes the development of new synthetic platforms for accessing modified peptides and proteins and interrogating the relationship between their structure and function. Chapter 2 describes an electrochemical platform for the site selective functionalisation of polypeptides that utilises the unique reactivity of selenocysteine to effect formation of valuable bioconjugates through stable selenoether linkages. Chapter 3 outlines the development and optimisation of a reaction manifold that leverages highly efficient reactivity between diselenides and H-phosphonates to install valuable near native mimics of phosphodiester-linked PTMs on peptides and proteins. Chapter 4 details the design of a high-throughput engineering workflow that enabled the rapid assembly of large analogue libraries based on the XC43 scaffold found in the saliva of the rat flea Xenopsylla cheopis, providing valuable insight into the relationship between the structure and activity of these modified anticoagulants.