One of the main limitations encountered during the chemical synthesis of
proteins through native chemical ligation (NCL) is the limited
solubility of some of the peptide segments. The most commonly used
solution to overcome this problem is to derivatize the segment with a
temporary solubilizing tag. Conveniently, the tag can be introduced on
the thioester segment in such a way that it is removed concomitantly
with the NCL reaction. We herein describe a generalization of this
approach to N-terminal cysteinyl segment counterparts, using a
straightforward synthetic approach that can be easily automated from
commercially available building blocks, and applied it to a well-known
problematic target, SUMO-2 (93 amino acids).
Total chemical synthesis of human interferon alpha-2b via native chemical ligation