C-Terminus

As the C- terminus or carboxy - terminus of that end of a protein or polypeptide refers to an amino acid which has a free carboxy group (COOH).

At the C -terminus of the protein ends on the ribosome, with the last amino acid is determined by the last amino acid coding triplet to the mRNA before the stop codon. Thus the protein is having a distinct beginning and an end. Through the peptide bond, in which a carboxy group is always associated with an α -position amino group of the next amino acid is at the beginning of a protein amino group and a free carboxy group at the end.

Consequently, it is called the C-terminus end of the molecule opposite a peptide N-terminus or amino -terminus.