What are peptides?
Peptides are short chains of amino acids. That is the whole definition, yet it explains their versatility: with 20 building blocks in any order, they serve as hormones, messengers, defence molecules and research tools.
In one sentence
A peptide forms when two or more amino acids join through peptide bonds; from about 50 amino acids and a stable fold onwards, one speaks of a protein.
The building blocks
Every amino acid shares the same backbone (amino group, acid group, central carbon) and has its own side chain, which makes it water-loving, fat-loving, charged or neutral. Sequences are written in three-letter code (Gly-His-Lys) or one-letter code (GHK).
The peptide bond
Two amino acids join when the acid group of one reacts with the amino group of the other, releasing water. The resulting bond is rigid and planar, which limits the shapes a chain can take. Water splits it again, slowly in solution and quickly with enzymes, which is why peptides are far more stable dry than dissolved.
Peptide, oligopeptide, protein
| Term | Length | Example |
|---|---|---|
| Dipeptide | 2 amino acids | Thymogen (Glu-Trp) |
| Oligopeptide | up to about 20 | Epitalon (4), BPC-157 (15) |
| Polypeptide | about 20 to 50 | Thymosin beta-4 (43), tesamorelin (44) |
| Protein | about 50 and more, folded | Growth hormone (191) |
Synthetic peptides in research
Research peptides are made chemically, one building block at a time on a solid support. This allows targeted changes: swapping amino acids, using mirror-image forms or attaching fatty acids to extend stability. Many products in our range are such variants, for example tesamorelin as a stabilised GHRH or retatrutide as an agonist at three hormone receptors.
Frequently asked questions
Are peptides and proteins the same?
No. Both are made of amino acids, but peptides are shorter and usually unfolded, proteins longer and folded into a fixed shape.
Are peptides natural substances?
Many occur in the body. Research peptides are synthesised, often as modified variants of natural templates.
Why do peptides keep better as a powder?
Because water attacks the peptide bond and other sensitive sites. Freeze-dried, these reactions barely take place.