Octreotide acetate is a cyclic octapeptide somatostatin analog designed around the receptor-active region of native somatostatin. Its compact structure contains two D-amino acids, an intramolecular disulfide bond, and a C-terminal threoninol residue that distinguish it from native somatostatin-14.
Octreotide preferentially activates somatostatin receptor subtype 2 (SSTR2) and is widely used as a reference ligand in somatostatin receptor pharmacology, GPCR signaling, receptor internalization and peptide structure–activity studies.
Product Information
| Property | Specification |
|---|---|
| Product Name | Octreotide Acetate |
| CAS No. | 79517-01-4 |
| Sequence | D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-ol |
| Peptide Length | 8 amino-acid residues |
| Molecular Weight | Approximately 1019.3 Da for the octreotide free peptide |
| Salt Form | Acetate |
| Disulfide Bond | Cys2–Cys7 |
| C-Terminus | Threoninol (Thr-ol) |
| Primary Target | SSTR2 |
| Research Areas | Somatostatin receptor pharmacology, GPCR signaling, peptide SAR, receptor internalization |
Octreotide Sequence and Cyclic Structure
The peptide sequence is:
D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-ol
An intramolecular disulfide bond between Cys2 and Cys7 constrains the peptide into the cyclic conformation associated with somatostatin receptor recognition.
Octreotide also contains D-Phe1 and D-Trp4 together with a reduced C-terminal threoninol residue. These structural features contribute to the distinct conformational and stability properties of the molecule compared with native somatostatin peptides.
We consider the disulfide state, D-amino-acid configuration and C-terminal Thr-ol to be part of the intended molecular identity. HPLC purity alone does not establish that all three structural features are correct.
Somatostatin Receptor Pharmacology
Octreotide shows its strongest pharmacological activity at SSTR2, with additional activity at SSTR5 and lower activity at SSTR3 in commonly used human receptor systems. Activity at SSTR1 and SSTR4 is substantially weaker.
| Receptor | Octreotide Research Profile |
|---|---|
| SSTR2 | Primary high-affinity receptor |
| SSTR5 | Secondary receptor activity |
| SSTR3 | Lower activity |
| SSTR1 / SSTR4 | Weak activity in commonly used receptor assays |
Cryo-EM studies have directly resolved octreotide bound to human SSTR2 and, more recently, SSTR5. These structures provide a molecular framework for studying receptor subtype selectivity, ligand recognition and analog design.
Researchers working with related receptor ligands can explore our Somatostatin Analogs collection.
Acetate Salt and Molecular Weight
Octreotide acetate should be distinguished from the octreotide peptide backbone when molecular weight and composition are reported.
The octreotide free peptide has a molecular weight of approximately 1019.3 Da. In the acetate form, acetate is present as a counterion and the total mass depends on acetate stoichiometry and the way the material is specified.
We recommend checking whether a reported molecular weight refers to octreotide itself or the complete acetate-containing material when comparing specifications between suppliers or preparing quantitative experiments.
Synthetic and Quality Control Considerations
Octreotide requires controlled assembly of D- and L-amino acids, correct Cys2–Cys7 oxidation and preservation of the C-terminal threoninol structure. Incorrect oxidation or stereochemistry can produce material with the expected nominal sequence but different biological behavior.
For receptor-binding and cell-based studies, we recommend confirming molecular identity together with chromatographic purity. Our Peptide Quality Control capabilities include analytical HPLC and mass spectrometry with batch-specific documentation according to the selected specification.
Octreotide analogs, sequence variants and cyclic peptide projects can also be evaluated through our Chemical Peptide Synthesis capabilities.
Frequently Asked Questions
How many amino acids are in Octreotide?
Octreotide contains eight amino-acid residues and is therefore classified as a cyclic octapeptide.
What is the disulfide bond in Octreotide?
The peptide contains one intramolecular disulfide bond between Cys2 and Cys7.
Which somatostatin receptor does Octreotide preferentially target?
Octreotide preferentially activates SSTR2. It also has activity at SSTR5 and SSTR3, with receptor potency depending on the assay system and experimental conditions.
Why can different molecular weights be reported for Octreotide Acetate?
The octreotide peptide itself has a molecular weight of approximately 1019.3 Da. Acetate is a counterion, so reported values can differ depending on whether the specification refers to the free peptide or an acetate-containing molecular composition.