The study of natural and unnatural peptides : changing medicinal & structural properties : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry

Abstract

Nature creates the foundations of life by linking together small, yet versatile, building blocks. Using this principle it can build information storage-molecules like DNA or functional catalyst like peptides and proteins. With the aid of non-covalent interactions these molecules form elegant 3D structures that allow them to have a range of functions and to complete a variety of tasks. However, the natural synthesis of the molecules are often limited by the biological resources available. As chemists, we have limitless choice in building blocks at our disposal, allowing us to make tweaks until we get the most efficient outcome. The purpose of this study is to see how chemists are able to improve on nature through the use of synthetic chemistry. This was attempted through two strands of research. The first strand tried to improve the efficiency of a naturally occurring peptide, opiorphin, by altering the chemical structure without inhibiting its analgesic potency. While the second project investigated a class of synthetic peptide, known as a foldamer, by using a unnatural amino acid building block. A viable design of a prodrug for opiorphin was proposed, which requires further research but has begun to show some promise. While the synthesis of a peptide was not achieved in the second project, issues seen during the synthesis of a dimer have been highlighted and alternative routes have been proposed. In addition, a novel substitution pattern for a cyclophane product has been reported.