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Body and drug basics

Amino acid

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Amino acids are the small molecules that link together to make peptides and proteins. There are about twenty common ones in the human body, each with slightly different chemical properties, and the order they are joined in is what makes one chain different from another. Think of them as letters in an alphabet: the same letters spell very different words depending on their order.

Why it matters here

When a record lists a sequence, it is listing amino acids in order. Two compounds can share almost every amino acid and still behave differently, which is why the full sequence is recorded rather than just the length.

What it is not

Not the same as the amino acid supplements sold for exercise, such as branched-chain amino acids. Those are free single amino acids taken as nutrients; the amino acids in a peptide are chemically joined into a chain and are not floating loose.

Also called

Once an amino acid is joined into a chain it is usually called a residue, so a chain of thirty amino acids is described as thirty residues long.

Compounds carrying this term

None on file yet. This term is in the controlled vocabulary but no compound record currently uses it — which is a statement about our coverage, not about the term.

See also