What is gonadorelin?

Gonadorelin in one table.

Two groups, one Nobel.

The sequence of GnRH was worked out in 1971 by the groups of Andrew Schally and Roger Guillemin, who isolated it from the hypothalami of hundreds of thousands of pigs and sheep, an effort that shared the 1977 Nobel Prize in Physiology or Medicine. The porcine and ovine sequences turned out to be identical to the human one, and the synthetic decapeptide, named gonadorelin, was being made within months of the structure being published.

A ring-free decapeptide with two caps.

Gonadorelin is a linear chain of ten residues. Its first residue is pyroglutamate, a glutamic acid whose side chain has cyclized onto its own amino group, which removes the free N-terminus and the water that the calculator would otherwise count: C₅₅H₇₇N₁₇O₁₄ for the open chain becomes C₅₅H₇₅N₁₇O₁₃, 1182.3 g/mol, for the hormone. The C-terminus is an amide. Glycine at position 6 and the Pro-Gly-NH₂ ending are the two places the analogues change. How to read a peptide sequence explains the pGlu and -NH₂ notation.

Position 6 and position 10.

Nearly every GnRH analogue swaps the glycine at position 6 for a D-amino acid, which protects the chain from cleavage, and many replace the final glycinamide with an ethylamide. Leuprolide uses D-leucine at 6 and the ethylamide; triptorelin uses D-tryptophan at 6 and keeps the glycinamide; buserelin uses D-serine with a tert-butyl group at 6 and the ethylamide. Each is a different molecule with its own mass, so a catalog entry has to say which one it is. Gonadorelin itself is the unchanged hormone.

A drug and a research compound.

Gonadorelin has been approved as a prescription drug in several formulations, including a human diagnostic product and veterinary products that remain on the US market, and its analogues are widely used medicines. The research compound is the same decapeptide supplied lyophilized as a laboratory reference material, labeled research use only; it is not a drug product. What research use only means covers the distinction.

The mass to expect.

Identity by mass spectrometry should find the neutral mass 1182.3, or a charge-state peak such as [M+2H]²⁺ near 592.2. The pyroglutamate is easy to miss on a label: a supplier who lists glutamic acid at position 1, or a mass near 1200, is describing a different molecule. Mass spectrometry for peptide identity explains the charge states and how to read a peptide COA the rest of the report.

Not currently supplied.

Helion does not currently supply gonadorelin. The research library covers it as a reference page alongside kisspeptin-10, the peptide upstream of it in the same hormonal axis, and peptide hormones explained places it among the other hypothalamic peptides.

Specs and storage by compound.