Synthesis of chemokines by native chemical ligation

Abstract

Publisher Summary This chapter describes the native chemical ligation technique focusing on its application to the synthesis of chemokines. Native chemical ligation allows two completely unprotected peptides to be joined through formation of a native peptide bond at the ligation site. The ligation is initiated by a chemoselective reaction between the N-terminal cysteine thiol of one peptide and a thioester functionality at the C-terminal residue of a second peptide. Exchange of the peptide thioester with the thiol side chain gives a thioester-linked intermediate as the initial covalent product. Chemokines are especially well suited for synthesis by native chemical ligation. Chemokines are 70- to 80-amino acid proteins with two disulfide bonds that are separated into two families based on the relative positions of the first two cysteine residues. These cysteines are either separated by one amino acid (α family) or are adjacent (β family). The third cysteine in both families is located roughly in the middle of the sequence; in interleukin-8, for example, it is located at residue 34 out of a total of 72 amino acids. Because of its central location, this cysteine can be utilized in native chemical ligation.