Chemical ligation is a set of techniques used for creating long
peptide or
protein chains. It is the second step of a
convergent approach. First, smaller peptides containing 30-50
amino acids are prepared by conventional chemical
peptide synthesis. Then, they are completely deprotected. Chemical ligation is the technique of coupling these peptides by chemoselective reaction to give a unique reaction product, usually in aqueous solution. With several coupling steps, proteins of up to 200-300
amino acids can be produced.