What is Peptide? (Peptide Glossary)

Peptides are short chains of amino acids, the same building blocks that make up proteins. The distinction is size: chains up to roughly 50 amino acids are called peptides, while longer chains are polypeptides and proteins. Despite their small size, peptides can be extraordinarily specific signaling molecules - insulin, oxytocin, and GLP-1 are all peptides or peptide-class hormones.

The research peptide market exists because peptides sit in a unique position: they are complex enough to have highly specific biological activity, yet small enough to be synthesized chemically at reasonable cost. Solid-phase peptide synthesis allows any sequence to be manufactured to order, which is why hundreds of research compounds - from BPC-157 to retatrutide - are available from specialist suppliers.

For buyers, the peptide structure explains the quality challenges. Each amino acid coupling in synthesis can fail, creating deletion sequences. Peptides degrade with heat, light, moisture, and rough handling. And because they are white powders that look identical, the entire market runs on laboratory verification - a peptide's appearance tells you nothing, which is why COAs are the foundation of vendor trust.