Optimizing the removal of an STmp protecting group

Disulfide rich peptides are unique in both their incredibly high cysteine content, but also in the stability imbued by the multiple disulfide bonds.  These peptides, stable under extreme conditions that would either denature or degrade a similar linear peptide, make disulfide rich peptides attractive as both therapeutics or as scaffolds upon which to construct non-native functionality.  Synthesizing these compounds, however, still remains a challenge.

I have discussed previously strategies that enable on-resin chemistry via orthogonal protecting groups.  These groups can be removed under mildly acidic, metal catalyzed, or even oxidizing conditions.  In today’s post, I’ll demonstrate the utility of using disulfide shuffling as a cysteine protection strategy. Continue reading Optimizing the removal of an STmp protecting group

Peptides containing cysteine: the role of scavengers in cleavage cocktail

Since the development of Fmoc-based solid phase peptide synthesis, a wide variety of cleavage cocktails have emerged.  Each cleavage cocktail contains a unique combination of scavengers designed to prevent either side reactions mediated by the released protecting groups or the side chains themselves, or both during the peptide cleavage reaction.  As the number of scientists performing peptide synthesis grows, the question “which cleavage cocktail should I use?” comes up more often than not.

In today’s post, I’ll highlight the role of of scavengers for peptides containing cysteine residues.

Continue reading Peptides containing cysteine: the role of scavengers in cleavage cocktail