C-Terminus
The end of a peptide or protein chain that has a free carboxyl group (-COOH). The C-terminus is the last amino acid added during peptide synthesis. Modifications at the C-terminus, such as amidation, are common in both natural and therapeutic peptides and can enhance biological activity and stability.
Technical Context
The C-terminus (carboxyl terminus) is the last amino acid added during protein synthesis. The free carboxyl group is susceptible to carboxypeptidase degradation. C-terminal amidation — converting -COOH to -CONH2 — is one of the most common modifications in natural peptide hormones (found in approximately half of all bioactive peptides) and often increases receptor binding affinity and biological potency. Many therapeutic peptides (including octreotide and several GnRH compounds) feature C-terminal amidation. This modification also provides resistance to carboxypeptidase degradation.