Oxytocin Technical Specification Sheet
Molecular Properties
| Parameter |
Value |
| Chemical Name |
Oxytocin / α-Hypophamine |
| Amino Acid Sequence |
Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂ (disulfide bridge: Cys1-Cys6) |
| Molecular Formula |
C₄₃H₆₆N₁₂O₁₂S₂ |
| Molecular Weight |
1007.19 g/mol |
| CAS Number |
50-56-6 |
| Sequence Length |
9 amino acids (cyclic nonapeptide with 6-membered ring) |
| Receptor Targets |
Oxytocin receptor (OXTR); secondary affinity for vasopressin receptors |
Physical Properties
| Property |
Specification |
| Appearance |
White to off-white lyophilized powder |
| Solubility |
Soluble in water, dilute acetic acid (0.1M), or saline at ≥1 mg/mL; pH 3.0-5.0 |
| pH (1% solution) |
3.5 - 5.0 (acidic for stability) |
| Hygroscopicity |
Moderate; desiccated storage required |
| Solution Stability |
Stable at 4°C for 5-7 days at pH 3-5; degrades rapidly at neutral/alkaline pH |
Analytical Specifications
| Test |
Specification |
| HPLC Purity |
≥98.0% |
| Mass Spectrometry |
Confirmed [M+H]⁺ = 1007.19 ± 0.5 Da; disulfide bridge intact |
| Peptide Content |
≥95% (by amino acid analysis) |
| Disulfide Bond Integrity |
≥98% (confirmed by mass spec and biological activity) |
| Endotoxin Level |
<1.0 EU/mg |
| Acetate Content |
≤5% |
| Water Content |
≤5% (Karl Fischer) |
Storage Parameters
| Condition |
Specification |
| Lyophilized Storage |
-20°C to -80°C, desiccated, protected from light |
| Lyophilized Shelf Life |
36 months when stored properly |
| Reconstituted Storage |
2-8°C for up to 7 days at pH 3-5; avoid neutral pH; -20°C for up to 3 months |
| Reconstitution Protocol |
Add 1.0 mL sterile water or 0.1M acetic acid to 1 mg vial; vortex gently for 30 seconds |
| Freeze-Thaw Cycles |
Maximum 3 cycles; single-use aliquots recommended |
| Light Sensitivity |
Moderate; store in amber vials and protect from direct light |
Research Dosing Reference
| Application |
Typical Dose Range |
Frequency |
Route |
| In Vitro Cell Studies |
10-1000 nM |
Single or repeated exposure |
Culture media |
| Small Animal Models (Rodent) |
0.1-10 μg/animal (50-500 μg/kg) |
Acute bolus or continuous infusion |
IV, IP, SC, intranasal |
| Behavioral Studies |
0.5-5 μg/kg (intranasal); 0.1-1 μg/kg (IV) |
Single dose 30-60 min pre-testing |
Intranasal or IV |
| Myometrial Contractility |
1-100 nM (in vitro); 0.5-5 mU/min infusion (in vivo) |
Continuous infusion |
Tissue bath or IV pump |
Note: Dosing information is for research reference only. Oxytocin is intended strictly for laboratory research. USP activity typically expressed as Units (U) or milliUnits (mU); 1 mg ≈ 500-600 IU.
Key Research Studies
| Year |
Study Focus |
Key Findings |
| 1953 |
First peptide hormone synthesis |
Du Vigneaud synthesized oxytocin; first polypeptide hormone chemically synthesized; confirmed sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂ with 1-6 disulfide bridge critical for activity |
| 1992 |
Oxytocin receptor cloning and characterization |
OXTR identified as Gq-coupled GPCR; demonstrated expression in uterus, mammary gland, brain; EC₅₀ for myometrial contraction ~1-5 nM; cross-reactivity with V1a receptor at high concentrations |
| 2005 |
Central nervous system effects on social behavior |
Intranasal oxytocin (24 IU in humans, 0.5-2 μg/kg in rodents) increased trust and social recognition; central OXTR activation modulated amygdala and prefrontal cortex activity in fMRI studies |
| 2013 |
Structure-activity relationship analysis |
Disulfide bridge (Cys1-Cys6) absolutely required; position 2 (Tyr) and 8 (Leu) critical for receptor selectivity; C-terminal Gly-NH₂ essential with removal reducing potency >1000-fold |
Mechanism of Action
| Biological Pathway |
Description |
| Receptor Binding |
Binds oxytocin receptor (OXTR), Gq-coupled GPCR; Kd ~1-5 nM; expressed in uterus, mammary, brain, heart, kidney |
| Signal Transduction |
Gq activation → phospholipase C → IP₃/DAG → Ca²⁺ release from SR/ER → smooth muscle contraction or neurotransmitter release |
| Peripheral Effects |
Myometrial contraction (uterus); milk ejection (mammary gland myoepithelial cells); modulation of cardiac function |
| Central Effects |
Modulates social recognition, trust, bonding, anxiety; acts as neuromodulator in limbic system, hypothalamus, brainstem nuclei |
| Half-Life |
3-5 minutes (IV); rapid enzymatic degradation by oxytocinase (placental leucine aminopeptidase) |
Quality Control Parameters
| Test Method |
Acceptance Criteria |
| Appearance (visual) |
White to off-white powder; no aggregation |
| Disulfide Bridge Confirmation |
ESI-MS shows intact cyclic structure; no reduced form detected |
| RP-HPLC (purity) |
Main peak ≥98.0%; no single impurity >0.5% |
| Biological Activity (USP) |
≥500 IU/mg by rat uterotonic assay |
| Enantiomeric Purity |
All L-amino acids; no D-isomer contamination |
Comparative Neurohypophyseal Peptides
| Peptide |
Sequence Difference from Oxytocin |
Primary Function |
| Oxytocin |
Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂ |
Uterine contraction, milk ejection, social behavior |
| Vasopressin (ADH) |
Position 3: Phe (vs Ile); Position 8: Arg (vs Leu) |
Water retention, vasoconstriction, blood pressure |
| Receptor Selectivity |
Single amino acid changes alter receptor preference |
OXTR vs V1a/V1b/V2 receptors |
Disclaimer: This product is intended for research use only. Not for human or veterinary diagnostic or therapeutic use. Oxytocin is a potent peptide; handle with appropriate laboratory protocols.