Ligation method and reagents to form an amide bond

The method and reagent for forming an amide linkage between a useful activated-carboxylic-acid derivative and アジド in composition of peptide, protein, and derivative-ized amino acid or sign amino acid, derivative-ized peptide, sign peptide, derivative-ized protein, or sign protein. Formation of ホスフィノチオエステル which reacts to アジド and brings about amide formation as a method is mentioned. The present invention offers the ホスフィノ thiol reagent converted into ホスフィノチオエステル which subsequently reacts an activated-carboxylic-acid derivative to アジド, and forms an amide linkage. The method and reagent of the present invention may be used for the ligation to two or more amino acid for gradual composition of peptide on a solid support medium, two peptide or more, or two protein fragmentation or more.