Peptides in the human body

Your body makes thousands of peptides. Many work as messengers, carrying signals from one place to another.

Peptide	Size	Made in	Its job
Insulin	51 (two chains)	Pancreas	Helps cells take up glucose from the blood
Glucagon	29	Pancreas	Raises blood glucose; works opposite insulin
Oxytocin	9	Hypothalamus	Involved in childbirth, breastfeeding and social bonding
Vasopressin	9	Hypothalamus	Helps the kidneys hold on to water
Glutathione	3	Most cells	Protects cells from damage by reactive molecules
Endorphins	About 30 (β-endorphin: 31)	Pituitary and brain	Natural signals involved in pain and reward

What a peptide hormone is

A peptide hormone is a hormone made of a chain of amino acids. It's usually released into the blood, travels to another part of the body, and binds to receptors on target cells to deliver its message.

Two famous firsts

• Oxytocin was the first peptide hormone ever made in a lab, by Vincent du Vigneaud in 1953. It won him the 1955 Nobel Prize in Chemistry.
• Insulin was the first protein ever sequenced, by Frederick Sanger. It won him the 1958 Nobel Prize.

See them all on the peptide history timeline.