The oxytocin amino acid sequence is a highly conserved mammalian nonapeptide structure defined as Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 (CYIQNCPLG-NH2), characterized by an intramolecular disulfide bridge between Cys1 and Cys6. Possessing a monoisotopic molecular weight of 1007.19 g/mol, oxytocin serves as a primary reference standard in preclinical studies examining neurohypophyseal peptide receptors, G protein-coupled receptor (GPCR) signaling cascades, and targeted ligand-receptor binding kinetics.
The oxytocin amino acid sequence is a highly conserved mammalian nonapeptide structure defined as Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 (CYIQNCPLG-NH2), characterized by an intramolecular disulfide bridge between Cys1 and Cys6. Possessing a monoisotopic molecular weight of 1007.19 g/mol, oxytocin serves as a primary reference standard in preclinical studies examining neurohypophyseal peptide receptors, G protein-coupled receptor (GPCR) signaling cascades, and targeted ligand-receptor binding kinetics.
The canonical oxytocin amino acid sequence consists of nine amino acid residues arranged in the primary sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 (CYIQNCPLG-NH2). In its natural state, the peptide features a C-terminal glycinamide residue and an essential intramolecular disulfide linkage joining the sulfur atoms of the cysteine residues at positions 1 and 6. This covalent bridge forms a rigid hexapeptide ring structure coupled to a flexible tripeptide tail (Pro-Leu-Gly-NH2), a conformational layout required for selective interaction with the oxytocin receptor (OXTR).
Investigating the structural integrity of this sequence is vital for laboratory evaluation. Disruption of the intramolecular disulfide bond—whether via reducing agents like dithiothreitol (DTT) or enzymatic cleavage—leads to complete inactivation of biological signaling in cell culture and tissue assay models. Researchers seeking reference standards for structural characterization can explore high-purity variants via the oxytocin 10mg product page for detailed analytical profiles.
The theoretical oxytocin molecular weight is calculated at 1007.19 g/mol (average atomic mass) with a exact monoisotopic mass of 1006.44 Da (C43H66N12O12S2). High-resolution electrospray ionization mass spectrometry (ESI-MS) or matrix-assisted laser desorption/ionization (MALDI-TOF) is routinely employed to verify this exact molecular mass, displaying a predominant protonated molecular ion peak [M+H]+ at m/z 1007.45.
Accurate determination of the oxytocin molecular weight relies upon accurate mass resolution to distinguish intact nonapeptide sequences from oxidative byproducts or truncated synthesis sequences. Minor structural deviations, such as methionine oxidation or deamidation of the glutamine/asparagine residues, shift the observed mass spectrum by predictable dalton increments. Detailed spectra and methodology are maintained in the PX1 mass spectrometry reference library.
Oxytocin shares substantial structural homology with arginine vasopressin (AVP), another neurohypophyseal peptide. Both molecules feature a cyclic nonapeptide architecture stabilized by a Cys1-Cys6 disulfide bridge. However, the oxytocin amino acid sequence differs from vasopressin at positions 3 and 8: oxytocin contains isoleucine at position 3 and leucine at position 8, whereas vasopressin features phenylalanine at position 3 and arginine at position 8 (Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly-NH2).
These subtle amino acid substitutions alter both spatial conformation and receptor selectivity profiles. Comparative assays evaluating vasopressin 10mg alongside oxytocin demonstrate how electrostatic charge variations at position 8 dictate binding preference between V1a/V2 receptors and OXTR. Furthermore, synthetic modifications such as N-terminus deamination yield analogues like carbetocin, which possess modified metabolic stabilities during enzymatic degradation studies. Laboratories conducting comparative GPCR assays can review related target profiles across the neurohypophyseal research hub.
Solid-phase peptide synthesis (SPPS) using standard Fmoc/tBu chemistry represents the primary manufacturing pathway for laboratory-grade oxytocin. The assembly proceeds from the C-terminal amidated glycine linked to a resin support, extending sequentially toward the N-terminal cysteine. Following full-chain elongation, the linear peptide undergoes selective oxidative cyclization under dilute conditions to favor intramolecular disulfide bond formation over intermolecular dimer production.
Improper folding or premature oxidation can generate misfolded dimers or linear oligomers, which compromise assay reproducibility. Automated microwave-assisted SPPS enables high crude purity, but rigorous post-synthesis purification via preparative reverse-phase high-performance liquid chromatography (RP-HPLC) remains mandatory to isolate the correctly folded monoisotopic peptide.
To satisfy international laboratory standards, research-grade oxytocin must undergo rigorous multi-point analytical verification. At PX1 Research, every production lot is subjected to dual-tier testing comprising RP-HPLC to establish chemical purity (>98.0%) and high-resolution ESI-MS to confirm the exact oxytocin molecular weight and sequence identity.
Furthermore, laboratory compounds manufactured in US-based GMP-compliant facilities undergo routine bacterial endotoxin testing (LAL assay) to guarantee endotoxin levels remain strictly below <0.01 EU/mg. ISO 17025 accredited laboratory certificates of analysis (COA) detailing lot-specific HPLC chromatograms, mass spectra, and water content (Karl Fischer titration) are provided transparently for every batch. Researchers can review full analytical documentation via the PX1 research database.
In preclinical model systems, oxytocin is utilized extensively to elucidate GPCR signal transduction pathways. Binding of oxytocin to the Gq/11-coupled oxytocin receptor activates phospholipase C (PLC), initiating intracellular inositol trisphosphate (IP3) production and subsequent calcium mobilization from the endoplasmic reticulum. In vitro cell cultures utilizing fluorescent calcium indicators frequently employ oxytocin to calibrate receptor responsiveness.
Additional laboratory models investigate oxytocin's role in modulating synaptic plasticity, neuroendocrine feedback loops, and downstream MAPK/ERK phosphorylation cascades. Animal studies involving central or peripheral tissue preparations frequently assess receptor density variations and cross-reactivity with vasopressinergic pathways under controlled experimental conditions.
Oxytocin is supplied as a lyophilized white powder to maximize long-term chemical stability. Upon receipt, lyophilized vials should be stored at -20°C or -80°C in a desiccated environment protected from light exposure. Under these conditions, the unconstituted nonapeptide maintains chemical stability for extended research timelines.
For laboratory reconstitution, researchers should utilize sterile bacteriostatic water or sterile phosphate-buffered saline (PBS, pH 7.4). Gentle rotation of the vial is recommended; aggressive vortexing should be avoided as mechanical shear forces can induce peptide aggregation or disulfide bond scrambling. Reconstituted stock solutions should be aliquoted into single-use polypropylene microtubes to avoid repeated freeze-thaw cycles and stored at -80°C. Complete handling protocols are outlined in the peptide solubility and reconstitution guide.
Acquiring consistent, highly pure peptides is essential for maintaining experimental reproducibility across multi-phase preclinical trials. Variations in salt content, residual organic solvents (such as trifluoroacetic acid), or trace endotoxins can introduce uncontrolled variables into sensitive cell culture and biochemical assays.
PX1 Research provides USA-manufactured research peptides supported by lot-specific analytical documentation and rapid distribution from fulfillment centers in California and Arizona. Institutional facilities requiring custom synthesis, specialized packaging formats, or volume scale-up can access dedicated support through the PX1 wholesale lab accounts portal.
What is the oxytocin amino acid sequence?
The oxytocin amino acid sequence is Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 (CYIQNCPLG-NH2). It contains a cyclic ring formed by an intramolecular disulfide bond between Cys1 and Cys6, attached to a C-terminal tripeptide tail.
What is the oxytocin molecular weight?
The exact monoisotopic oxytocin molecular weight is 1006.44 Da, with an average chemical molecular weight of approximately 1007.19 g/mol (chemical formula: C43H66N12O12S2).
How does the oxytocin amino acid sequence differ from vasopressin?
Oxytocin differs from arginine vasopressin at positions 3 and 8. Oxytocin contains isoleucine at position 3 and leucine at position 8, whereas vasopressin contains phenylalanine at position 3 and arginine at position 8.
What is the chemical formula of oxytocin?
The chemical formula of laboratory-grade oxytocin nonapeptide is C43H66N12O12S2.
Why is the disulfide bond between Cys1 and Cys6 critical for oxytocin function?
The Cys1-Cys6 disulfide bond stabilizes the cyclic hexapeptide ring structure. In vitro studies confirm that reduction of this bond destroys the peptide's spatial conformation, preventing binding to the oxytocin receptor.
How is oxytocin purity verified by PX1 Research?
PX1 Research verifies oxytocin purity using high-performance liquid chromatography (RP-HPLC) to confirm >98% purity and electrospray ionization mass spectrometry (ESI-MS) to verify molecular weight and sequence integrity, documented on lot-specific COAs.
What is the recommended reconstitution solvent for laboratory oxytocin?
Oxytocin is readily soluble in sterile bacteriostatic water or phosphate-buffered saline (PBS, pH 7.4). Once dissolved, solutions should be aliquoted and frozen to prevent degradation.
What are the endotoxin limits for PX1 research peptides?
PX1 Research peptides undergo LAL endotoxin testing to ensure levels remain below <0.01 EU/mg, preventing endotoxin interference in cell culture and preclinical assays.
How should lyophilized oxytocin be stored in the lab?
Lyophilized oxytocin should be stored desiccated at -20°C or -80°C away from direct light. Avoid repeated exposure to ambient humidity prior to reconstitution.
Does PX1 Research ship oxytocin peptides directly within the USA?
Yes, PX1 Research dispatches research-grade peptides with same-day shipping (Monday through Friday) from state-of-the-art dispatch facilities in California and Arizona.
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