Scientists Say: Peptide

These tiny chemical chains are the building blocks of proteins and more

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This is the chemical structure of pepsin, a large molecule that breaks down proteins into smaller peptides. The pepsin molecule is itself made of peptides, here shown in different colors.

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Peptide (noun, “PEP-tie-d”)

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.

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Bethany is the staff writer at Science News for Students. She has a Ph.D. in physiology and pharmacology from Wake Forest University School of Medicine.

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