A polypeptide is a chain of amino acid residues linked by peptide bonds. The term describes chain chemistry; calling a chain a polypeptide alone does not establish that it is folded or functional. The gene expression example N–methionine–alanine–C contains two amino acid residues and one peptide bond; the twelve-residue example under protein contains eleven peptide bonds. See IUPAC-IUB: amino-acid symbols and representation of residues in chains.
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