What is Semax?
Our records list Semax under CAS 80714-61-0, formula C37H51N9O10S, average molecular weight 813.92 and the seven-residue sequence H-Met-Glu-His-Phe-Pro-Gly-Pro-OH, filed as an ACTH(4-7) analogue. The first four residues, Met-Glu-His-Phe, are that adrenocorticotropic hormone fragment, and the C-terminal Pro-Gly-Pro is the synthetic addition.
The sequence dictates the handling. The single methionine accounts for the one sulfur atom in the formula and makes the sulfoxide the first degradation product to expect, while the histidine adds pH sensitivity and a route for metal-catalysed oxidation. The phenylalanine gives weak absorbance near 257 nm but no useful 280 nm signal. As with the tuftsin analogue elsewhere in this catalog, the proline-rich tail blunts carboxypeptidase attack.
The literature uses Semax as a tool in neuropharmacology. Rodent studies have examined expression of brain-derived neurotrophic factor and nerve growth factor in models of cerebral ischaemia, and cell work has looked at transcriptional responses in neural and immune lineages. Because the parent fragment lies outside the steroidogenic region of the hormone, the analogue is described as lacking corticotropic activity. The receptor mediating the neurotrophic readouts has not been identified, which is the central open question.
Reconstitution & handling
Sterile or bacteriostatic water clears the cake with gentle swirling. Prepare with freshly drawn water and keep contact with headspace air short, because the methionine oxidises readily. Keep trace metal contamination low, since copper and iron catalyse methionine and histidine oxidation. Concentration is labelled mass divided by diluent volume, corrected by net peptide content.
Storage & stability
Store the sealed dry vial at -20 °C with desiccant and protected from light. Reconstituted material belongs at 2 to 8 °C in single-use aliquots and should not be frozen and thawed repeatedly. Oxidation is the specific risk here: a stock that has stood warm or aerated can show a sulfoxide shoulder on re-analysis even when it still looks clear. Amber glass and filled, low-headspace aliquots both help.
How it's tested
Purity is determined by reversed-phase HPLC at 214 and 220 nm, where methionine sulfoxide elutes just ahead of the parent peak and is reported when present. Identity is confirmed by mass spectrometry against the theoretical average mass of 813.92, a sixteen unit increase indicating oxidation. Net peptide content, water and residual counterion are reported, and a lot-matched certificate of analysis is available on request.