Reviewed by: Todd Smith, PhD
noun, plural: polypeptides
A polymer of amino acids joined together by peptide bonds
A polymer produced by a living organism is called a biopolymer. There are four major classes of biopolymers: (1) polysaccharides, (2) polypeptides, (3) polynucleotides, and (4) fatty acids. A polypeptide is an unbranched chain of amino acids that are linked together by peptide bonds. The peptide bond links the carboxyl group of one amino acid to the amine group of the next amino acid to form an amide. Short polypeptides may be named based on the number of monomeric amino acids that comprise them. For instance, a dipeptide is a peptide comprised of two amino acids sub-units, a tripeptide is a peptide comprised of three amino acid sub-units, and tetrapeptide is a peptide comprised of four amino acid sub-units.
One or more polypeptides that occur together and function in a particular way are referred to as proteins. Proteins often bind to small molecules ( ligands, coenzymes), to other proteins, or to other macromolecules (DNA, RNA, etc.)
Word origin: Greek polýs (many) + peptide