peptide bond

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A simplified diagram of the lysozyme protein from hen's egg white, showing a single blue peptide chain with numbered red dots marking amino acid residues from the N-terminal (1) to the C-terminal (129).

Diagram showing two peptide links, each with atoms labeled for oxygen, carbon, nitrogen, and hydrogen. A dotted line represents a hydrogen bond connecting the two peptide links, illustrating chemical bonding between them.

peptide bond

chemistry

Also known as: peptide link

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July 1, 2026

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A simplified diagram of the lysozyme protein from hen's egg white, showing a single blue peptide chain with numbered red dots marking amino acid residues from the N-terminal (1) to the C-terminal (129). — Lysozyme and protein conformation The simplified structure of lysozyme from hen's egg white has a single peptide chain of 129 amino acids. The amino acid residues are numbered from the terminal α group (N) to the terminal carboxyl group (C). Circles indicate every fifth residue, and every tenth residue is numbered. Broken lines indicate the four disulfide bridges. Alpha-helices are visible in the ranges 25 to 35, 90 to 100, and 120 to 125.

A peptide bond is the chemical bond that links amino acids together to form peptides and proteins. This bond is formed through a condensation reaction where a water molecule is released, connecting the carboxyl group of one amino acid to the amino group of another. Specifically, it's the bond between carbon and nitrogen atoms within the amide linkage. Peptides are organic molecules structurally similar to proteins but smaller, and they play vital roles in biological functions, including hormones and antibiotics. The number of amino acids determines the type of peptide: dipeptides have two, oligopeptides have a few, and polypeptides have many. Proteins are essentially large polypeptides composed of numerous amino acid residues linked by peptide bonds.123456

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amino acid
Peptide bond
Amino acids can be linked by a condensation reaction in which an ―OH is lost from the carboxyl group of one amino acid along with a hydrogen from the amino group of a second, forming a molecule of water and leaving the two…
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Amino acids can be linked by a condensation reaction in which an ―OH is lost from the carboxyl group of one amino acid along with a hydrogen from the amino group of a second, forming a molecule of water and leaving the two…
Read More

chemical bonding
The hydrogen bond
…is the existence of the peptide link, the group ―CO―NH―, which appears between each pair of adjacent amino acids. This link provides an NH group that can form a hydrogen bond to a suitable acceptor atom and an oxygen atom, which can act as a suitable receptor. Therefore, a peptide…
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…is the existence of the peptide link, the group ―CO―NH―, which appears between each pair of adjacent amino acids. This link provides an NH group that can form a hydrogen bond to a suitable acceptor atom and an oxygen atom, which can act as a suitable receptor. Therefore, a peptide…
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metabolism
The catabolism of proteins
…linking adjacent amino acids (peptide bonds) must be hydrolyzed; this process releases the amino acids constituting the protein. The utilization of dietary proteins thus requires the operation of extracellular digestive enzymes; i.e., enzymes outside the cell. Many microorganisms secrete such enzymes into the nutrient media in which they are…
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…linking adjacent amino acids (peptide bonds) must be hydrolyzed; this process releases the amino acids constituting the protein. The utilization of dietary proteins thus requires the operation of extracellular digestive enzymes; i.e., enzymes outside the cell. Many microorganisms secrete such enzymes into the nutrient media in which they are…
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peptide
…amide group is called a peptide bond. Some or all of the peptide bonds, which connect the consecutive triplets of atoms in the chain regarded as the backbone of the molecule, can be broken by partial or complete hydrolysis of the compound. This reaction, producing smaller peptides and finally the…
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…amide group is called a peptide bond. Some or all of the peptide bonds, which connect the consecutive triplets of atoms in the chain regarded as the backbone of the molecule, can be broken by partial or complete hydrolysis of the compound. This reaction, producing smaller peptides and finally the…
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polyamide
…usually referred to as the peptide bond.) More narrowly defined, the polyamides are an important group of industrially produced synthetic polymers. The most important is nylon, actually an extremely versatile class of polymers that are made into indispensable fibres and plastics. Another class of polyamides made into fibres is the…
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…usually referred to as the peptide bond.) More narrowly defined, the polyamides are an important group of industrially produced synthetic polymers. The most important is nylon, actually an extremely versatile class of polymers that are made into indispensable fibres and plastics. Another class of polyamides made into fibres is the…
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protein
The amino acid composition of proteins
…is customary to write the structure of peptides in such a way that the free α-amino group (also called the N terminus of the peptide) is at the left side and the free carboxyl group (the C terminus) at the right side. Proteins are macromolecular polypeptides—i.e., very large molecules (macromolecules)…
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…is customary to write the structure of peptides in such a way that the free α-amino group (also called the N terminus of the peptide) is at the left side and the free carboxyl group (the C terminus) at the right side. Proteins are macromolecular polypeptides—i.e., very large molecules (macromolecules)…
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Emil Fischer
Enzyme and protein research
…together by amide bonds, called peptide bonds by Fischer, who established the presence of this class of molecules in proteins by developing synthetic methods for creating long chains of amino acids held together by peptide bonds to make proteinlike substances. In 1907 he created a polypeptide with 18 amino acids…
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…together by amide bonds, called peptide bonds by Fischer, who established the presence of this class of molecules in proteins by developing synthetic methods for creating long chains of amino acids held together by peptide bonds to make proteinlike substances. In 1907 he created a polypeptide with 18 amino acids…
Read More