Polypeptide Group

Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. Amino acids comprise peptides as residues. Peptides are usually "linear" with an N-terminal (amine group) and C-terminal (carboxyl group) residue at the ends. Cyclic peptides are a distinct class.