12.8.5 Synthesis of Peptides

In peptide synthesis, one amino acid is protected at its amino end with group Y and the second is protected at its carboxyl end with a group Z. The condensation of these two protected amino acids using DCC generates a peptide bond. As per the requirement, one of the protecting groups can then be removed and a third protected amino acid can be introduced to the second peptide bond. Repetition of the procedure leads to the desired polypeptide. For example:

Protection and Deprotection of Carboxyl Group     

• The carboxyl group can be protected by converting it into its t-butyl ester using isobutylene in the presence of sulfuric acid.

• The protecting group can also be easily removed using mild acid hydrolysis.

 

Protection and Deprotection of Amino Group

 (9-Fluorenyl)methyoxycarbonyl group (Fmoc) is commonly used for the protection of the amino group of amino acid.

• The protecting group can also be easily removed by treatment with amine base, such as piperidine.