By BioLabs Research · Last reviewed: October 10, 2026
Catalog names in this class get reused until they stop meaning anything. "AOD-9604", "hGH 177–191", "hGH 176–191" and "fragment 176–191" are not automatically the same reagent. If the vial, the certificate of analysis (COA) and the purchase order disagree on the first residue or on the disulfide, the material is not the listing you ordered. This page is an identity note for the AOD-9604 catalog listing: what the sequence is, how it relates to the growth hormone numbering, and which fields settle identity.
The published identity
PubChem lists AOD-9604 as a 16-residue peptide with an intramolecular disulfide bond.
| Field | Public record |
|---|---|
| Name | AOD-9604 |
| Sequence (one-letter) | YLRIVQCRSVEGSCGF |
| Residues | 16 |
| Disulfide | Cys7–Cys14 (intramolecular) |
| Molecular formula | C78H123N23O23S2 |
| Molecular weight | 1815.1 g/mol |
| CAS | 221231-10-3 |
Source: PubChem CID 71300630. These values describe which molecule is being sold. They are not a purity figure and not a lot result. Salt form and net peptide content still have to come from the lot certificate.
How the numbering works
The "177–191" label refers to positions in mature human growth hormone (UniProt P01241). The precursor is 217 residues long and includes a 26-residue signal peptide; the mature chain is 191 residues. In mature numbering:
- Residues 177–191 read LRIVQCRSVEGSCGF, 15 residues starting with leucine.
- Residues 176–191 read FLRIVQCRSVEGSCGF, 16 residues starting with phenylalanine.
- AOD-9604 reads YLRIVQCRSVEGSCGF: tyrosine followed by residues 177–191. In other words, it matches 176–191 with tyrosine in place of phenylalanine at the first position.
The two cysteines correspond to a disulfide bond in the parent protein, which UniProt places between positions 182 and 189 of the mature chain. In the 16-residue peptide those are positions 7 and 14.
Where catalogs mix names
A vial labeled AOD-9604 with paperwork that says "176–191" has not told you which first residue you have. A label that says "177–191" may describe a 15-residue peptide with no tyrosine at all. Two practical checks resolve it:
- Sequence line on the COA. It should print YLRIVQCRSVEGSCGF, or the full three-letter form starting Tyr-Leu-Arg, if the order said AOD-9604. A phenylalanine start, or a sequence starting with leucine, is a different material.
- Intact mass against a stated theoretical mass. An observed mass with no theoretical value next to it does not establish identity.
Mass differences worth knowing
These offsets are our own calculations from standard average residue masses, starting from the PubChem value of 1815.1 for the disulfide form:
| Variant | Approximate mass | Difference |
|---|---|---|
| AOD-9604, disulfide formed | 1815.1 Da | reference |
| Same sequence, disulfide not formed | 1817.1 Da | +2 Da |
| Phe instead of Tyr at position 1 (176–191) | 1799.1 Da | −16 Da |
| No first residue (177–191, 15 residues) | 1651.9 Da | −163 Da |
The 2 Da disulfide difference is small, so the certificate should state whether the reported mass is for the oxidized (disulfide) form. The 16 Da tyrosine–phenylalanine difference is easy to resolve by mass spectrometry, provided the lab reports the expected value it compared against.
What the name is not
AOD-9604 is not intact growth hormone, which is a 191-residue protein. It is not interchangeable with a "176–191" vial from another source, because the first residue differs. A catalog line with this name is a laboratory reagent identified by sequence and mass, nothing more.
Quality markers on the lot certificate
Beyond identity, look for the markers that apply to any synthetic peptide. Reviews of peptide impurities list deletion sequences, truncations and oxidation products among the common by-products of synthesis (D'Hondt et al., 2014). A useful AOD-9604 certificate includes the lot number, the HPLC method with column and wavelength, the observed mass with its expected value and disulfide state, and a counter-ion and water statement. See HPLC area percent vs net peptide content.
Receiving checklist for an AOD-9604 lot
Before the vial goes into stock, confirm:
- The carton, the order and the invoice name the same catalog listing.
- The lot number on the vial appears on the certificate.
- The certificate prints the full 16-residue sequence, starting with tyrosine.
- The observed mass is reported next to the expected value, with the disulfide state stated.
- The HPLC method is identified by column and wavelength.
- The vial is sealed, dry and intact.
If the sequence line starts with phenylalanine or leucine, or the mass does not match the stated form, record the lot as "identity unresolved" and ask for a revised certificate.
Questions to send before ordering
When a listing elsewhere uses one of the overlapping names, ask three things: the full sequence with its first residue, the expected mass and whether it refers to the disulfide form, and the registry number printed on the certificate with the public record it belongs to. Those answers separate AOD-9604 from the 176–191 and 177–191 peptides without any guesswork.
Reading the certificate
Read identity before purity. Confirm the sequence line, then the mass and disulfide state, and only then the HPLC figure, because a high area percent means nothing if the main peak is a different sequence. Our guide on how to read lot documents walks through each field, and the COA library shows complete certificates for catalog listings.
Next step: Request the lot certificate for the AOD-9604 listing before you order.
Related reading
References
- PubChem Compound Summary, CID 71300630 (AOD-9604): YLRIVQCRSVEGSCGF, C78H123N23O23S2, MW 1815.1, CAS 221231-10-3. https://pubchem.ncbi.nlm.nih.gov/compound/71300630
- UniProtKB P01241 (SOMA_HUMAN), Somatotropin: signal peptide 1–26, chain 27–217, disulfide 208–215 (precursor numbering). https://www.uniprot.org/uniprotkb/P01241/entry
- D'Hondt M, Bracke N, Taevernier L, et al. Related impurities in peptide medicines. J Pharm Biomed Anal. 2014;101:2–30. https://pubmed.ncbi.nlm.nih.gov/25044089/
For research use only. Not for human or veterinary use.