Semax is a short peptide with a structure derived directly from a natural hormone fragment. The brevity of the sequence makes the analysis comparatively simple, but places its own demands on the separation.
What is Semax?
Semax is a heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. The first four amino acids correspond to fragment 4 to 7 of adrenocorticotropic hormone, supplemented by the C-terminal tripeptide Pro-Gly-Pro, which increases stability against peptidases. The molecular mass is approximately 814 Da.
In addition to the basic form, an N-acetylated variant is described in the literature. Acetylation increases the mass by approximately 42 Da and is unambiguously recognisable by mass spectrometry. A product designation without an addition leaves the variant open.
Research context
Semax is described in the neuroscience research literature, predominantly in publications from the Russian-speaking world. In the European Union there is no marketing authorisation as a medicinal product. For laboratory contexts it is relevant that the available literature concerns different preparations and variants and that assignments are not possible without analytical characterisation.
Analytical identification
- RP-HPLC on C18 phases with a water/acetonitrile gradient. Semax is a comparatively polar peptide and elutes early; with too weak a starting gradient there is a risk that the substance appears in or near the dead volume and is poorly separated from polar impurities. Detection takes place at 214 to 220 nm; the phenylalanine it contains additionally permits detection at approximately 257 nm.
- LC-MS confirms the mass of around 814 Da as a singly charged ion and at the same time separates the acetylated from the non-acetylated form.
The terminal methionine residue is sensitive to oxidation. Methionine sulfoxide increases the mass by 16 Da and typically appears in RP-HPLC as a slightly earlier eluting secondary peak. This pair of mass difference and retention shift is a readily interpretable marker for sample quality.
Purity and analytical interpretation
With heptapeptides, deletion sequences are usually well separated from the main peak, which makes evaluation easier. Practically relevant are above all oxidation products of the methionine as well as, with polar peptides, the question of whether the gradient permits sufficient separation in the early range at all. An area-percent value without a chromatogram and without a gradient specification therefore cannot be assessed.
Documentation and batch traceability
Traceable documentation names the batch, method, conditions and measured mass and, for Semax, additionally states whether the acetylated or the non-acetylated form is present.
Storage and Stability
Because of the oxidation sensitivity of the methionine, contact with air, heat and light are the principal influencing factors. Common laboratory practice is to store the lyophilised material dry, protected from light and refrigerated, for longer stocks at minus 20 degrees Celsius. These details concern exclusively the handling of laboratory substances.
Further research resources
- HPLC in peptide analysis
- LC-MS in peptide analysis
- Understanding peptide purity
- Analysis and certificates
Associated catalogue products
This page serves exclusively as scientific and analytical information. It contains no dosage, application or treatment instructions. Products are not intended for use in humans or animals.