Chemical Modification of Proteins

Abstract

The invention relates to methods for selectively converting a cysteine residue in a peptide or protein to the dehydroalanine (Dha) residue. The method also works on selenocysteine and substituted cysteine and selenocysteine residues, resulting in the Dha residue which may be converted to any natural or unnatural amino acid residue desired without the alteration of the remainder of the peptide or protein. The invention also allows ligation of a desired peptide at any point rather than at a point where there should be a naturally occurring cysteine, thereby allowing native chemical ligation to be used in the synthesis of peptides that do not contain cysteine. The methodology allows for the synthesis of very large peptides.