Glossary term
Peptide
A short chain of amino acids, the same building blocks that make up proteins.
Why it matters
Peptides are smaller than proteins and can act as signals in the body. That signaling role is why they are studied for so many different goals.
A peptide is a chain of amino acids joined together, typically shorter than a full protein. Some peptides occur naturally in the body and act as messengers; others are made in a lab to study or copy those messages.