Oxytocin
Also known as OXT, oxytocin nonapeptide
Oxytocin is a well-characterized endogenous nonapeptide neurohormone, a long-studied reference molecule in social-neuroscience and receptor research. A research-use profile: structure and research context.
Oxytocin is unusual among the compounds in a peptide catalog because it is not novel, engineered, or speculative — it is one of the most thoroughly characterized peptides in all of biology. It was among the first peptide hormones to have its structure fully determined and chemically synthesized, work that is now foundational to peptide chemistry itself.
For that reason this page reads a little differently. Oxytocin is an established endogenous neurohormone with a settled structure, so the emphasis here is on what is genuinely well documented — its composition and the research fields that use it as a standard tool — rather than anything speculative. As with every compound listed, no physiological, behavioral, or use claims are made.
A nine-residue cyclic peptide with a disulfide bridge between the two cysteine residues (positions 1 and 6) forming a six-residue ring, and a C-terminal glycinamide. It differs from the closely related peptide vasopressin at only two positions.
A textbook nonapeptide
Oxytocin is a chain of nine amino acids with a distinctive architecture: two cysteine residues, at positions 1 and 6, are joined by a disulfide bridge that closes a six-membered ring, leaving a short three-residue tail that ends in a glycinamide. This ring-plus-tail structure is a classic teaching example of a cyclic peptide.
It is nearly identical to vasopressin, differing at only two of the nine positions. That close relationship between two neurohormones with distinct signaling roles is itself a long-standing subject of structure–function research.
The social-neuroscience research context
Oxytocin's endogenous role is as a neurohormone — a peptide released within the nervous system that acts on its own G-protein-coupled receptor. In the research world it has become a standard probe in social and behavioral neuroscience, where the oxytocin receptor system is one of the most-studied peptide-signaling pathways. Describing it as a research tool in that field is a statement about where scientists study it, not a claim about effects.
Because it is endogenous and well defined, oxytocin also serves as a reference and comparison molecule in broader peptide-receptor and peptide-synthesis research.
Handling notes for a disulfide peptide
The defining handling consideration for oxytocin is its disulfide bridge. Cyclic disulfide peptides are sensitive to conditions that can reduce or scramble that bond, so laboratory handling emphasizes keeping the compound sealed, cold, and dry until a protocol calls for it. A certificate of analysis should show a mass consistent with the intact disulfide-bridged nonapeptide.
These are research areas the compound is associated with in the literature — not medical claims or intended uses.
Handling & storage
Supplied lyophilized. Because it contains a disulfide bridge, it is kept sealed, cold, and dry, and in research settings reconstituted with bacteriostatic water only when a protocol requires it, then refrigerated. Handle per accepted laboratory practice.
Verify a certificate by lot →Common questions
Yes. It is an endogenous nonapeptide neurohormone and one of the earliest peptide hormones to have its structure determined and be chemically synthesized.
It is a nine-residue peptide closed into a ring by a disulfide bridge between its two cysteines, with a short amidated tail — and it differs from vasopressin at only two positions.
Cyclic disulfide peptides can be reduced or scrambled under the wrong conditions, so keeping the compound sealed, cold, and dry preserves the intact bridged structure.
This monograph is a research-use reference. It describes composition and the contexts in which the compound has been studied — it is not medical advice, a description of effects, or a recommendation for use. Sold strictly for laboratory and research use; not for human or animal consumption.