Understanding Peptide Names, Sequences and Nomenclature

Peptide names can look like an impenetrable mix of letters, numbers, and hyphens. But there's a logic behind them, and once it clicks, a lot of names become self-explanatory — some literally spell out the molecule's structure.

Amino Acids Are the Building Blocks

Peptides are chains of amino acids, and there are 20 standard ones, each with a one-letter and a three-letter code. Lysine is K (or Lys), Proline is P (Pro), Valine is V (Val), Glycine is G (Gly), Histidine is H (His), and so on. These codes are the alphabet that peptide names and sequences are written in.

When the Name Is the Sequence

Some peptides are named directly after their amino acid sequence. KPV is simply Lysine-Proline-Valine — three amino acids, spelled out in their one-letter codes. GHK is Glycine-Histidine-Lysine. Once you know the codes, these names tell you exactly what the molecule is made of, in order.

Other Naming Conventions

Not every peptide is named after its sequence. Some carry laboratory or development codes, some are named after the hormone they mimic or the receptor they target, and some — like GHK-Cu — append a component, in this case the copper (Cu) ion the peptide binds. Longer peptides are impractical to spell out letter by letter, so they take shorter names instead, with the full sequence recorded separately.

Why Sequence Matters

The exact sequence determines a peptide's molecular weight, its behaviour, and how it's verified — mass spectrometry confirms identity precisely because each sequence has a known, calculable mass. For how that verification works, see our guide on HPLC and mass spec testing, and for a specific example, our overview of the KPV tripeptide.