Peptides share the same raw material as proteins, the 20 proteinogenic amino acids, but they are much smaller. That difference in size changes how they behave: a peptide usually has a single, very specific function, such as activating one particular receptor, and it rarely adopts the complex fold of a protein.
The body produces thousands of signalling peptides: hormones (insulin, GLP-1, oxytocin), neurotransmitters and local modulators. Many research peptides are exact copies of those natural molecules, fragments of them or analogues designed to last longer or act more selectively.
By length they are classed as dipeptides (2 amino acids), tripeptides (3, such as GHK-Cu or glutathione), oligopeptides (up to about 20) and polypeptides. The sequence, meaning which amino acid sits in each position, fully defines the identity of the molecule.
Everything else (purity, stability, half-life, how it is reconstituted) depends on the peptide being exactly the declared sequence. That is why identity is confirmed by mass spectrometry and purity by HPLC in every batch.
Related terms
Learn it in depth at the Peptide University
- Lyophilization and excipients · Module 11
- Amylin, the oral route and the next generation · Module 3
- Physical degradation: aggregation and adsorption · Module 11
- Related impurities and counterions · Module 7
- Routes of administration and bioavailability · Module 8
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Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).