Peptide ligation and semisynthesis.

Semisynthesis is used to create defined analogues of proteins by the chemical manipulation of peptide fragments largely derived from the natural protein and the subsequent reassembly of those fragments into a near-native conformation. In common with the total synthesis of proteins, it requires efficient and non-destructive methods for peptide religation. Recently, a wide range of chemoselective ligation schemes have been elaborated that now permit the assembly of minimally protected peptides from either synthetic or natural sources.