DOCUMENTED BY BATCHSelank at a glance
Selank is a synthetic heptapeptide catalogued as a research reference compound. It is structurally related to the endogenous peptide tuftsin and carries a defined seven-residue sequence, a single molecular formula, and a molecular weight near 752 g/mol. The identity data below are drawn from the public PubChem record (CID 11765600) and are intended as a laboratory reference, not as any statement of use.
| Property | Value |
|---|---|
| Compound name | Selank |
| CAS number | 129954-34-3 |
| PubChem CID | 11765600 |
| Molecular formula | C33H57N11O9 |
| Average molecular weight | ~751.9 g/mol |
| Amino-acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Residue count | 7 (heptapeptide) |
| Physical form | White lyophilised powder |
Molecular identity and sequence
Selank is a linear peptide built from seven amino-acid residues in the order Thr-Lys-Pro-Arg-Pro-Gly-Pro, that is threonine, lysine, proline, arginine, proline, Gly, and a terminal proline. The corresponding molecular formula is C33H57N11O9, giving an average molecular weight of approximately 751.9 g/mol. Because three of the seven residues are proline, the backbone contains several imide bonds, a structural feature that is often reflected in the peptide’s chromatographic behaviour and in the fragment pattern observed by mass spectrometry.
Structural context
In the published chemical literature Selank is described as a synthetic analog of tuftsin, a short endogenous peptide with the core sequence Thr-Lys-Pro-Arg. Selank extends that tuftsin core with a C-terminal Pro-Gly-Pro segment. Cataloguing it against the tuftsin parent is useful for a research setting only as background on how the sequence was derived; it is not a description of any activity. For entity confirmation, the CAS registry number 129954-34-3 and PubChem CID 11765600 are the canonical identifiers.
Analytical identity and purity testing
Every batch offered here is identity-confirmed and purity-checked at the USC Alfred E. Mann Multi-Omics Mass Spectrometry Core, a university analytical laboratory, before it is listed. Two orthogonal techniques anchor the result. Liquid chromatography coupled to mass spectrometry (LC-MS), including high-resolution mass spectrometry (HRMS), measures the intact mass of the peptide and compares it against the theoretical value calculated from C33H57N11O9. A match within a few parts per million confirms that the material is the intended heptapeptide rather than a truncated or deletion sequence. Reversed-phase high-performance liquid chromatography (HPLC) then resolves the main peak from process-related impurities; the separation performance of the column determines how cleanly minor species are distinguished, and the area-percent of the main peak is reported as estimated purity.
For Selank specifically, an HRMS reading close to the calculated monoisotopic mass, together with a dominant single HPLC peak, is the signature of a correctly assembled sequence. The full data set is published as a Certificate of Analysis rather than summarised as a single claim.
How to read a Certificate of Analysis
A Certificate of Analysis (COA) for a research peptide typically lists the compound name, the batch or lot code, the analytical date, and the laboratory that performed the work. The identity section shows the observed mass against the expected mass from the molecular formula. The purity section shows the HPLC chromatogram and the calculated area-percent of the main peak. When reviewing a Selank COA, confirm that the stated formula reads C33H57N11O9, that the reported mass is consistent with roughly 751.9 g/mol, and that the batch code on the document matches the label on the vial. Archived certificates for listed batches are kept in the COA library.
Appearance and handling
As supplied, Selank is a white to off-white lyophilised powder. For solution preparation in a laboratory setting, peptides of this class are commonly dissolved in sterile water; the peptide’s high proportion of polar residues, including lysine and arginine, generally supports aqueous handling. Repeated freezing and thawing of a prepared solution is usually minimised to preserve sequence integrity, and a cryoprotectant is sometimes included when longer storage of a solution is required. These are general handling notes for reference material and are not instructions for any application.
Why batch-level testing matters
Short peptides are assembled residue by residue, and the most common quality issues are deletion sequences, incomplete coupling, and residual synthesis reagents. None of these are visible to the eye in a white powder. Independent LC-MS and HPLC data are the only reliable way to distinguish a correct Thr-Lys-Pro-Arg-Pro-Gly-Pro heptapeptide from a near-identical impurity. Publishing the university-lab COA per batch is the mechanism that makes that distinction transparent for a research audience. Other short peptides catalogued as research references, such as Semax, are documented with the same batch-level identity and purity testing.
For laboratory research use only. Not for human or veterinary use.
Frequently asked questions
What is the CAS number and molecular formula of Selank?
Selank is registered under CAS number 129954-34-3, with PubChem CID 11765600. Its molecular formula is C33H57N11O9, corresponding to an average molecular weight of approximately 751.9 g/mol.
What is the amino-acid sequence of Selank?
Selank is a heptapeptide with the seven-residue sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro (threonine, lysine, proline, arginine, proline, Gly, proline). It is described in the chemical literature as a synthetic analog of the endogenous peptide tuftsin, extending the tuftsin core Thr-Lys-Pro-Arg with a C-terminal Pro-Gly-Pro segment.
How is the identity of a Selank batch confirmed?
Identity is confirmed by liquid chromatography coupled to mass spectrometry, including high-resolution mass spectrometry (LC-MS and HRMS). The intact measured mass is compared against the theoretical mass calculated from C33H57N11O9. Reversed-phase HPLC then resolves the main peak from impurities to establish estimated purity. Both results are recorded on the Certificate of Analysis.
Where is Selank tested?
Each listed batch is identity-confirmed and purity-checked at the USC Alfred E. Mann Multi-Omics Mass Spectrometry Core, a university analytical laboratory, using LC-MS and HRMS. The resulting Certificate of Analysis is published rather than summarised as a single claim.
What physical form does Selank take?
Selank is supplied as a white to off-white lyophilised powder. Its molecular identity is defined by the formula C33H57N11O9 and the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro; the batch code on the vial should match the code on its Certificate of Analysis.