Total chemical synthesis of homogeneous N-glycoprotein
The total chemical synthesis of glycoprotein is greatly facilitated by the development of native chemical ligation (NCL) and obtaining methods for homogeneous complex type N-glycan from egg yolk. Based on these methods, in 2008, The Kajihara and Dawson group achieved the chemical synthesis of glycoprotein monocyte chemotactic protein-3 (MCP-3), a CC-chemokine that consists of 76-amino acid and a complex type N-glycan (Fig4: Total synthesis of MCP-3 having biantennary sialyloligosaccharides).[23] The two steps of sequential NCL using three unprotected peptide segments 38, 39 and 40 afforded native glycoprotein MCP-3 43. The challenging synthesis of glycopeptide thioester 38 was achieved by using either Fmoc SPPS protocols or Boc SPPS protocols.
