AOD-9604 is a development code, not a chemical name. Here we document AOD-9604 as an identity reference: what the sequence is, which part of which protein it is taken from, what mass to expect, how it behaves under reverse-phase HPLC, and how a buyer can confirm that the material in a vial is what the label says. What AOD-9604 does is outside its scope, and it offers no preparation, handling or dosing guidance.
The sequence behind AOD-9604
AOD-9604 is a 16-residue peptide:
Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (one-letter code YLRIVQCRSVEGSCGF)
The two cysteines, at positions 7 and 14 of the peptide, are joined by a disulfide bond, which closes the middle of the chain into a ring. All residues are standard L-amino acids, and the C-terminus is a free acid rather than an amide. The molecular formula of the disulfide-bonded peptide is C78H123N23O23S2 and its average molecular mass is approximately 1815.1 g/mol.
What the name refers to: residue numbering
AOD-9604 is derived from the C-terminal end of human growth hormone (hGH), a 191-residue protein. The residue numbering of that tail region is where most naming confusion begins, so it is worth setting out precisely.
The last sixteen residues of hGH, positions 176–191, read Phe-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe. AOD-9604 is residues 177–191 of hGH with an added N-terminal tyrosine. Because hGH has a phenylalanine at position 176, the result can be described in two equivalent ways:
- hGH(177–191) with an extra tyrosine at the N-terminus; or
- hGH(176–191) with the phenylalanine at position 176 replaced by tyrosine.
Both describe the same 16-residue molecule. What neither describes is the unmodified hGH(176–191) fragment, which starts with phenylalanine instead of tyrosine and is a different compound. The two differ by a single hydroxyl group — about 16 daltons — so a label or listing that says only “hGH fragment 176–191” is not by itself enough to tell which one is meant. The first residue of the stated sequence, and the observed mass, are what settle it.
How AOD-9604 behaves on reverse-phase HPLC
AOD-9604 is a mid-sized peptide with a mix of character: two arginines and a glutamate give it charge, while leucine, isoleucine, two valines and the aromatic tyrosine and phenylalanine give it hydrophobic surface. On a C18 column with a water/acetonitrile gradient and trifluoroacetic acid it retains well and elutes in the middle of a typical peptide gradient.
With one tyrosine, one phenylalanine and no tryptophan, its absorbance at 280 nm is weak. Purity is read at around 214 nm on the peptide bond, which is where all peptide-related impurities are visible.
The disulfide adds impurity classes that a linear peptide does not have. The reduced form, with two free thiols instead of the bridge, is 2 daltons heavier and usually elutes at a slightly different time from the cyclised peptide. Intermolecular pairing can give disulfide-linked dimers at roughly twice the mass. Standard synthesis impurities — deletion sequences and incompletely deprotected species — also apply. Our guide to peptide synthesis impurities covers what each of these looks like.
What an analysis for AOD-9604 should show
A useful certificate reports the column chemistry and dimensions, the mobile phase and gradient, the detection wavelength, the retention time, the integrated peak area with the integration window visible, and a mass confirmation. The mass confirmation should land at approximately 1815 for the disulfide-bonded peptide. A figure about 2 daltons higher indicates the reduced form; a figure about 16 daltons lower points to the phenylalanine-starting hGH(176–191) fragment rather than AOD-9604. Electrospray spectra of a peptide this size typically show doubly and triply charged ions, which our article on mass spectrometry and peptide identity explains how to read.
The certificate should also state net peptide content separately from chromatographic purity and name the counter-ion. With two arginines and a free N-terminal amine, AOD-9604 is normally isolated as a trifluoroacetate or acetate salt, and the counter-ion contributes weight to every milligram of powder without contributing peptide. Our explainer on TFA vs acetate counter-ions covers why the salt form matters.
Confirming identity independently
Search on the sequence, not the designation. Public chemical databases index AOD-9604 by its sequence, its formula C78H123N23O23S2 and its synonyms, and public protein databases carry the full hGH sequence, so the C-terminal tail can be checked residue by residue. Confirm three things on the published analysis: that the sequence starts with tyrosine, that the observed mass sits near 1815, and that the disulfide-bonded form is the one reported.
How AOD-9604 is supplied here
AOD-9604 5mg is supplied as a lyophilised powder in a sealed vial. It is analysed by independent reverse-phase HPLC, with the result published for that product. The product listing for AOD-9604 gives the vial size together with the published HPLC purity. No batch or lot code appears on a AOD-9604 vial, so the crimp and cap color are what tie it to the published result.
Frequently asked questions
What is the amino acid sequence of AOD-9604?
Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (YLRIVQCRSVEGSCGF), with a disulfide bond between the two cysteines.
Is AOD-9604 the same as hGH fragment 176-191?
Not exactly. AOD-9604 is hGH(177–191) with an added N-terminal tyrosine, equivalent to hGH(176–191) with phenylalanine 176 replaced by tyrosine. The unmodified 176–191 fragment starts with phenylalanine and is about 16 daltons lighter.
What molecular weight should I expect for AOD-9604?
Approximately 1815.1 g/mol for the disulfide-bonded free base, formula C78H123N23O23S2. A salt form weighs more per milligram, which is why the counter-ion has to be declared alongside the mass.
Why does the disulfide matter analytically?
Because the cyclised and reduced forms differ by 2 daltons and usually by retention time. A certificate should make clear which form was measured.
Research use only. All products supplied by Battle Born Peptides are laboratory reference materials for in-vitro research and analytical use by qualified professionals. They are not drugs, foods, dietary supplements, cosmetics or medical devices; they are not approved by the FDA or any other regulator for use in humans or animals; and they are not intended to diagnose, treat, cure, mitigate or prevent any disease, or to affect the structure or any function of the body of humans or animals. Nothing in this article is preparation, handling or dosing guidance. See our full research-use terms.