Amino Acid
Also known as: amino acids · residue · residues
The building-block molecules of peptides and proteins; each contributes one residue to the chain.
Amino acids are the monomer building blocks of peptides and proteins. Each has a central carbon bearing an amino group, a carboxyl group, a hydrogen and a distinctive side chain (the "R group") that gives it its character. Twenty standard amino acids make up most biological peptides.
When amino acids link via peptide bonds, each one within the resulting chain is called a residue. The specific order of residues is the peptide’s sequence, which determines its shape and function.
A peptide’s name often encodes its residues — for example the tripeptide GHK-Cu is glycine-histidine-lysine plus copper.
RELATED TERMS
Peptide Bond
The covalent amide bond linking amino acids into a peptide chain — the defining structural feature of every peptide.
Amino-Acid Sequence
The specific order of amino-acid residues in a peptide — its "primary structure" — which dictates shape and activity.
Tripeptide / Tetrapeptide
Short peptides named for their residue count — three (tri), four (tetra), five (penta) amino acids.
N-terminus & C-terminus
The two ends of a peptide chain: the N-terminus has a free amino group, the C-terminus a free carboxyl group.
Educational content, not medical advice. All products supplied for research purposes only — not for human consumption.