Oxytocin
Oxytocin is a nine-residue peptide hormone, Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2, with a disulfide bridge between the two cysteine residues.
- TypePeptide
- FormulaC43H66N12O12S2
- Average mass1007.19 g/mol
- CAS50-56-6
- Vesta listings2
Reference page for laboratory use · updated 2026-10-30
Overview
Oxytocin at a glance
Oxytocin is made in the hypothalamus and has an extensive literature, including detailed reviews of the oxytocin receptor and its signalling pathways.
In the laboratory it is a standard reference peptide for receptor pharmacology, and it is widely used as an analytical test compound because its mass and disulfide are well defined.
Structure
The ring formed by the Cys1-Cys6 disulfide gives the molecule its characteristic shape. The C-terminus is an amide.
Identity
Identity data
| Name | Oxytocin |
|---|---|
| Type | Peptide |
| Research area | Neuropeptide-derived peptides |
| Molecular formula | C43H66N12O12S2 |
| Monoisotopic mass | 1006.4365 Da |
| Average molecular weight | 1007.19 g/mol |
| CAS number | 50-56-6 |
| Sequence | Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 |
| Ring structure | Cyclic: disulfide bond between two cysteines |
| PubChem record | CID 439302 |
The formula was calculated independently from the written sequence and matches the PubChem record exactly. Reference data retrieved on 2026-10-30. Compare these values with the batch certificate of analysis, using the compound identity file template.
Expected values
Mass spectrometry reference
Ions calculated from the monoisotopic mass 1006.4365 Da. Use them to check an LC-MS result; for larger peptides the instrument usually reports a deconvoluted mass close to 1007.2 Da instead.
| Ion | m/z |
|---|---|
| [M+H]+ | 1007.4438 |
| [M+2H]2+ | 504.2255 |
| [M+Na]+ | 1029.4257 |
| [M+K]+ | 1045.3997 |
Read the guide to average and monoisotopic mass for how these values are calculated.
Quality
Analytical notes for batch documents
- The reduced form (open ring) is 2.016 Da heavier. A COA should show that the disulfide form is the main species.
- Oxytocin is also sensitive to deamidation of the glutamine and asparagine residues (+0.984 Da).
- Mass shifts to look for in this sequence: deamidation of Asn or Gln (+0.984 Da); a reduced disulfide (+2.016 Da).
- The molecular weight of a vial of powder includes counter-ions and water; the share of the powder that is peptide is the net peptide content.
Terms used on this page: Peptide, Disulfide bond, C-terminus, Deamidation.
Vesta listings
Oxytocin formats and prices
| Product | Per vial | SKU | Price per kit | Price per vial |
|---|---|---|---|---|
| Oxytocin | 5 mg | OT/OXY | $44.78 | $4.48 |
| Oxytocin | 10 mg | OT/OXY-10MG | $57.84 | $5.78 |
Prices are per kit of 10 vials in US dollars. Shipping is paid by the customer and is shown in the cart. Volume savings of 5 %, 8 % and 10 % apply from $350.00, $600.00 and $1,000.00. See the full price list.
Published literature
Selected scientific literature
Bibliographic details were read from PubMed on 2026-10-30. The papers are listed for scientific reference; Vesta makes no claim about the use of its research materials in people or animals.
- The Oxytocin Receptor: From Intracellular Signaling to BehaviorJurek B, Neumann ID · Physiol Rev · 2018 · PMID 29897293
- Is Oxytocin "Nature's Medicine"?Carter CS, Kenkel WM, MacLean EL et al. · Pharmacol Rev · 2020 · PMID 32912963
Questions
Frequently asked questions
What is Oxytocin?
Oxytocin is a nine-residue peptide hormone, Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2, with a disulfide bridge between the two cysteine residues.
What is the molecular weight of Oxytocin?
Oxytocin has the formula C43H66N12O12S2, an average molecular weight of 1007.19 g/mol and a monoisotopic mass of 1006.4365 Da. A salt form, a different counter-ion or a metal complex changes the molecular weight printed on a certificate of analysis, so compare like with like.
How can I check the identity of a batch of Oxytocin?
Compare the intact mass measured by LC-MS with the expected values on this page, for example [M+2H]2+ at m/z 504.2255. Confirm that one main HPLC peak carries that mass and that the batch code on the report matches the vial. The guides on mass spectrometry and on certificates of analysis explain each step.
Which Oxytocin products does Vesta list?
Vesta lists 2 products for Oxytocin: 5 mg, 10 mg per vial in kits of 10 vials. Prices are shown per kit in US dollars, and shipping is paid by the customer.