The invention mainly relates to a method for manufacturing a polypeptide of formula: X1&mdash；X&Prime；&mdash；X2&emsp；&emsp；(III) X1 and X2 each representing a peptide fragment, and X&Prime； representing an amino acid residue comprising a thiol function, said method comprising at least one step of ligation reaction between a polypeptide of formula: X1&mdash；N(CH2CH2SH)2&emsp；&emsp；(I) and a polypeptide of formula: H&mdash；X&Prime；&mdash；X2.&emsp；&emsp；(II) The invention also relates to the polypeptides of formula (I) themselves and the method for obtaining them, as well as resin supports suitable for obtaining them.
