New to research peptides? The terminology can be dense. This glossary defines the words you’ll see most often on product pages, Certificates of Analysis, and research literature — in plain language. Bookmark it as a quick reference.
Core terms
| Amino acid | The building block of peptides and proteins. |
| Peptide bond | The chemical link joining one amino acid to the next. |
| Residue | A single amino acid unit within a chain. |
| Sequence | The specific order of amino acids that defines a peptide. |
| Analogue | A modified version of a natural molecule designed for stability or selectivity. |
Handling & form
| Lyophilized | Freeze-dried into a stable powder for storage. |
| Reconstitution | Dissolving the powder into a liquid for research use. |
| Diluent | The liquid used to reconstitute (e.g. bacteriostatic water). |
| Freeze–thaw cycle | Repeated freezing and thawing, which can degrade a peptide. |
Quality & testing
| Purity | The percentage of the sample that is the intended peptide. |
| HPLC | High-performance liquid chromatography — the standard purity test. |
| Mass spectrometry | Confirms a peptide’s identity by measuring its mass. |
| COA | Certificate of Analysis — the document reporting identity and purity. |
Mechanism terms
| Agonist | A molecule that activates a receptor. |
| Receptor | A cell protein that a molecule binds to produce an effect. |
| Half-life | The time for half of a compound to break down or clear. |
| Research use only (RUO) | Intended for laboratory study, not for human or animal use. |
Want the bigger picture? See What Are Research Peptides? and Peptides vs Proteins.
Research use only. For educational purposes. Compounds referenced are not approved for human or veterinary use, and nothing here is medical advice. Sold strictly for in vitro laboratory research by qualified professionals.
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