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Why is peptide-bond formation called a condensation reaction?
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Amino acid
The structure and function of amino acids.
Peptide-bond formation is classified as a condensation reaction because it involves the combination of two molecules with the elimination of a smaller molecule—in this case, water.12
During this process, the carboxyl group of one amino acid loses an –OH group, while the amino group of a second amino acid loses a hydrogen atom. These components combine to form a water molecule, leaving the two amino acids linked by an amide bond, which is specifically referred to as a peptide bond. This reaction is fundamental to the formation of polymers such as proteins, which are composed of long chains of amino acid residues joined by these bonds.1