Peptide Synthesis - Protecting Groups

Protecting Groups

Amino acids have reactive moieties at the N- and C-termini, which facilitates amino acid coupling during synthesis. Many amino acids also have reactive side chain functional groups, which can interact with free termini or other side chain groups during synthesis and peptide elongation and negatively influence yield and purity. To facilitate proper amino acid synthesis with minimal side chain reactivity, chemical groups have been developed to bind to specific amino acid functional groups and block, or protect, the functional group from nonspecific reactions. These protecting groups, while vast in nature, can be separated into three groups, as follows:

• N-terminal protecting groups
• C-terminal protecting groups (mostly used in liquid-phase synthesis)
• Side chain protecting groups

Purified, individual amino acids are reacted with these protecting groups prior to synthesis and then selectively removed during specific steps of peptide synthesis.