Sequential native peptide ligation strategies for total chemical protein synthesis.

Total chemical synthesis of proteins is usually achieved by assembling unprotected peptide segments using site-specific and chemoselective native peptide ligation methods. Access to large proteins often requires the assembly of at least three segments due to the current limits of solid phase synthesis of individual peptide segments. The aim of this tutorial review is to present the basic concepts and challenges underlying the design of sequential peptide ligation strategies using solution or solid phase chemistry. A special emphasis is given to C-to-N and N-to-C three-segment assembly strategies, which potentially give access to proteins composed of up to 150 amino acid residues.