Oxidative folding of conotoxins: chemical and biological developments to efficiency of production of short, cysteine-rich peptides

Oxidative folding is one of the key challenges hampering the development of peptidebased compounds as therapeutics. While disulde-rich peptides are often thought to be more appealing drug lead compounds because of their stable, highly-crosslinked structure, their oxidative folding to the correct disulde connectivity is often dicult, and is optimized in a peptide-specic way. This work advanced knowledge of chemical and biological means to improve oxidative folding of conotoxins. Herein I present a generalized folding protocol suitable for folding diverse disulde-rich peptides. I also show that the incorporation of selenocysteines to replace a disulde bridge with a diselenide eectively adds an intramolecular oxidative folding catalyst, where this bridge had previously been assumed to be static, with any folding improvements being a consequence of conformational eects. These are followed by a discussion of oxidative folding mechanisms in vivo, relating energy expenditure to directing disulde isomerization to the desired connectivity, as well as a novel analysis tool to consider the codon conservation of the cysteine residues that comprise the disulde scaold. This work represents signicant improvements to chemical strategies to eciently produce disulde-rich peptides and genetic analyses towards a better understanding of the role oxidative folding plays in the evolution of disulde scaolds of cysteine-rich peptides.