What a peptide is
You'll see the word "peptide" on every page of this site. Here's what it actually means, in about three minutes.
A short chain of building blocks
Your body builds things out of amino acids. There are 20 common ones, and they snap together end to end like beads on a string. A long string, often hundreds of beads that fold into a 3-D shape, is a protein. A short string is a peptide.
Where "short" ends is a convention, not a law. Chains up to about 50 amino acids are usually called peptides. Insulin, at 51, gets called both.
- GHK
- 3 amino acids (GHK-Cu is GHK holding a copper ion)
- BPC-157
- 15 amino acids
- Semaglutide
- 31 amino acids, plus a fatty side chain
- A typical protein
- Hundreds of amino acids
Why researchers care about them
Many of the body's own messengers are peptides. They're signals: one cell releases a peptide, another cell has a receptor that recognizes it, and something changes. Insulin and the gut hormone GLP-1 are famous examples.
Because the body already uses peptides as signals, scientists make lab versions, sometimes copies and sometimes tweaked ones, to study how those signals work. A few have become approved medicines after years of trials. Most have not, and are studied only in the lab.
How research peptides are made
Research peptides aren't extracted from animals. They're built in a lab one amino acid at a time on tiny resin beads, then cut loose, purified and freeze-dried into the powder you see in a vial. That process is why purity testing and COAs matter: a small mistake in the build gives you a slightly different molecule.
Next
A peptide sold for research and a peptide medicine your doctor prescribes can share a name and still be very different things. That's the next read: Research peptide vs. approved drug.
Want the full chemistry? What are peptides? A beginner's guide →