This is a short chain of amino acids — the simple molecules that make up proteins. Amino acids link together in strings. A short string from two to about 100 amino acids earns the name “peptide.”
Peptides can hold many roles in a cell. They can join forces to make up a larger protein. When those proteins are broken down, the trash products are peptides. Peptides can also do work alone. Some small peptides serve as messengers between cells in the brain and body. Those messengers might kill pain, trigger a cell to grow or turn on the immune system to repel an invader.
In a sentence
Scientists are studying peptides from frogs to see if they can be used to help people fight infections.