AOD-9604 is a sixteen-residue synthetic peptide: residues 177 to 191 of human growth hormone, the C-terminal end of the 191-residue hormone, with a tyrosine added at the N-terminus and a disulfide bond between cysteines 182 and 189. It is usually named "fragment 176-191" for that reason, the added tyrosine standing in for position 176. Its mass is 1815.1 and its CAS number 221231-10-3. It was designed to keep the region of the hormone associated with lipid metabolism and discard the part that binds the growth hormone receptor, and its literature consists of rodent studies from the group that designed it. This post explains where the fragment sits in the hormone, what the disulfide loop means for handling, what Heffernan and colleagues measured in 2001, and what the current certificate reports for the AOD-9604 in the catalogue, supplied as a 5 mg lyophilized powder for laboratory research use only.
Where does the fragment sit in the hormone?
Human growth hormone is a 191-residue protein with four helices and two disulfide bonds. One of those bonds, between cysteines 182 and 189, closes a small loop near the C-terminus. AOD-9604 is that loop and the residues around it, cut free of the rest.
| Human growth hormone | AOD-9604 | |
|---|---|---|
| Residues | 191 | 16 (Tyr + 177 to 191) |
| Mass | About 22,000 | 1815.1 |
| Disulfides | Two (53-165, 182-189) | One (182-189, retained) |
| Growth hormone receptor binding | Yes, through helices the fragment lacks | No |
| Origin | Recombinant protein | Solid-phase synthesis, then oxidative folding of the loop |
The design logic is the same fragment logic behind KPV and PE-22-28: isolate the part of a larger molecule thought to carry one activity, and lose the rest. Here the rest includes the receptor-binding surface, so the fragment cannot act as growth hormone does. Whatever it does, it does through some other route, and the literature has not settled which.
What does the disulfide mean for handling?
The disulfide post and the oxytocin post cover the general problem: a peptide with a disulfide loop is only the intended molecule while the loop is intact and correctly paired.
For AOD-9604 there is one loop and one way to pair it, so scrambling is not the risk it is for multi-disulfide peptides. Reduction is: a reducing environment, dithiothreitol in a buffer or a strongly reducing cell medium, opens the loop and leaves a linear peptide two mass units heavier. Conversely, an incompletely folded synthesis leaves free thiols that oxidise unpredictably in solution. The practical rules are the oxytocin post's rules: no reducing agents in the stock, cold and dark storage, and an awareness that a reconstituted vial left at room temperature for days is a vial whose loop has been given time to react. The glutathione post explains the thiol chemistry.
What did the rodent studies measure?
Two papers from Heffernan and colleagues in 2001, both in mice.
International Journal of Obesity. Obese mice treated chronically with either full-length human growth hormone or the fragment were compared with untreated obese mice. The fragment-treated animals showed increased fat oxidation and lower body weight than controls, in the same direction as the hormone-treated animals.
Endocrinology. The same comparison extended to mice lacking the beta-3 adrenergic receptor, to test whether the fragment's effect on lipid metabolism ran through that receptor. The paper reported that the fragment's effect persisted in the knock-out animals, which argued against that particular mechanism, and that the fragment did not share the hormone's effect on glucose handling.
Those are the findings: chronic treatment, obese mice, lipid metabolism readouts, one mechanism excluded. They are not findings about any other species, and the trial-data post explains why an in-vitro design should take from them a question rather than a result. Later human work by the developing company was not published in a form that changes that picture, and the product page's description, "studied in lipid metabolism work", is the honest summary.
What does the certificate report?
Lot AOD5-0803, certificate COA7615, issued by Bioviridian Inc. on 17 August 2026 against a 5 mg sample of white lyophilized powder, published unaltered on the certificate page.
| Certificate line | Result | What it tells you |
|---|---|---|
| Identity, LC-MS/MS | AOD-9604, observed mass 1815.1 | The oxidised, loop-closed peptide; the reduced form would read 1817.1 |
| Content, HPLC quantitation | 5.16 mg | Overage against the 5 mg label |
| Purity, RP-HPLC at 214 nm | 99.78% | One main peak; a reduced or scrambled fraction would show as a separate peak |
| Endotoxin | < 0.05 EU/mL | Suitable for cell work |
| Heavy metals | Conforms | August 2026 layout |
The two-unit difference between the folded and reduced forms is within what LC-MS/MS resolves, and the purity chromatogram is the second check: an open loop changes retention. The LC-MS post covers what the method can settle.
How many molecules are in 5 mg?
| Vial | Moles | In 1 mL | In 2 mL |
|---|---|---|---|
| 5 mg | 5 mg ÷ 1815.1 g/mol = 2.75 µmol | 2.75 mM | 1.38 mM |
The molarity post covers the arithmetic. AOD-9604 sits in the catalogue's metabolic section with 5-Amino-1MQ, which the 5-Amino-1MQ post explains is not a peptide at all, and apart from the growth hormone axis compounds, tesamorelin and ipamorelin, which act upstream at pituitary receptors the fragment does not touch. TB-500 is the other fragment-of-a-larger-protein in the catalogue, from an unrelated protein.
Frequently asked questions
Is AOD-9604 the same as growth hormone?
No. It is sixteen residues from the hormone's C-terminus, lacking the receptor-binding surface. It does not act at the growth hormone receptor.
Why is it called 176-191 when it starts at 177?
Because the added N-terminal tyrosine is counted as position 176 by convention. The residues from the hormone itself are 177 to 191.
Does it have a disulfide bond?
Yes, one, between cysteines 182 and 189, retained from the hormone. The certificate mass, 1815.1, is the loop-closed form.
What did the studies show?
Increased fat oxidation and lower body weight in obese mice treated chronically, without the hormone's effect on glucose, and persistence of the effect in beta-3 adrenergic receptor knock-out mice. Rodent findings, 2001.
What should the methods section record?
"AOD-9604 (Tyr-hGH 177-191, CAS 221231-10-3)", the supplier, lot AOD5-0803, certificate COA7615, the observed mass, the stock concentration, and confirmation that no reducing agent was present in the stock. The methods-section post has the template.
References
- Heffernan MA, Thorburn AW, Fam B, et al. Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment. International Journal of Obesity 2001;25(10):1442-1449. doi.org/10.1038/sj.ijo.0801740
- Heffernan M, Summers RJ, Thorburn A, et al. The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta3-AR knock-out mice. Endocrinology 2001;142(12):5182-5189. doi.org/10.1210/endo.142.12.8522
- PubChem, National Library of Medicine. AOD-9604, CID 71300630, C78H123N23O23S2, 1815.1 g/mol, CAS 221231-10-3. Read 28 September 2026. pubchem.ncbi.nlm.nih.gov/compound/71300630
Every product mentioned is sold for laboratory research use only and is not for human or animal use. Nothing on this page describes or recommends use of the material sold here in humans or animals.
