Semax: A Research Primer

Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro, seven amino acids assembled by chemical synthesis rather than drawn from any tissue. Its first four residues copy a short stretch of adrenocorticotropic hormone, the ACTH(4-10) fragment, capped with a proline-glycine-proline tail.

What Semax is

Semax is a fully synthetic peptide, and the accurate way to describe it is as an ACTH(4-10) analogue. The natural ACTH(4-10) fragment runs Met-Glu-His-Phe-Arg-Trp-Gly. Semax keeps the first four of those residues, Met-Glu-His-Phe, then swaps the rest for Pro-Gly-Pro. That Pro-Gly-Pro tail is the reason chemists reach for this design: a terminal proline pair slows the enzymatic clipping that short peptides are otherwise prone to, which makes the molecule more stable than the raw fragment it descends from.

The heptapeptide is usually abbreviated to its single-letter code, MEHFPGP. It carries a Russian research pedigree, having been developed at institutes there, which is why a fair amount of the older literature on it reads as translated rather than originally English. None of that changes what ships. A vial of Semax is the isolated, manufactured peptide at reagent grade, not an extract of anything.

The chemistry

The identity numbers are what stay fixed no matter whose label you are reading, so they are the first thing to check against a certificate.

• CAS number: 80714-61-0
• Molecular formula: C37H51N9O10S
• Sequence: Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP)
• Class: synthetic heptapeptide, ACTH(4-10) analogue
• Length: 7 residues

The single sulfur atom in that formula comes from the methionine residue at the N-terminus, the only sulfur-bearing amino acid in the chain. If a mass figure on a certificate looks off by a small amount, methionine is worth a glance, since it is the residue most likely to pick up an extra oxygen during handling. Match the CAS number first and the sequence second when you are confirming that two sources describe the same molecule, because a name can be spelled a dozen ways and a formula can be mistyped, while a registry number cannot.

Where it appears in the research literature

Semax turns up mainly in neuroscience and cognitive research. Those are subject areas, named here as topics and nothing else.

I am not going to paraphrase what any of that work reported. A supplier summarizing study conclusions would be putting words in the literature's mouth, and the honest version of this section is the pointer, not the summary. If you want the primary sources, search on "Semax", the MEHFPGP code, or the CAS number and read them directly. That route tells you what the papers actually say better than any secondhand gloss on a product page.

How it is supplied and handled

Semax is supplied as a lyophilized solid, which is to say freeze-dried to a dry powder, and it stores cold.

Peptides travel as a dry cake because a solid survives shipping far better than a solution does. Keep the vial at -20C, sealed until you are working with it, and away from moisture and repeated temperature swings. With methionine in the sequence, limiting air and light exposure is the sensible default, since that residue is the one most sensitive to oxidation over long storage. There is usually a small amount of bulking agent in the vial so there is something visible to work with, and a proper certificate accounts for that filler when it reports the mass. This is storage and handling for a laboratory material, not preparation guidance.

How the lots are tested

Identity and purity are the two questions a certificate of analysis answers. Mass spectrometry confirms the molecule matches the label, and HPLC measures how much of the sample is the target peptide against related impurities, read at 220 nm, the wavelength peptide bonds absorb at.

Kits Peptides has each lot it stocks third-party tested by an independent laboratory, so verification comes from outside the supplier rather than off its own bench. If you have not worked through one of these documents before, there is a walkthrough on [how to read a peptide COA](/research/how-to-read-a-peptide-coa) using real reports, plus a broader [checklist for sourcing research peptides in Canada](/research/buying-research-peptides-canada). The [Semax product page](/products/semax) shows the current batch and whether it is in stock. Kits Peptides ships tracked from Vancouver, BC across Canada.

*All products are supplied as laboratory reagents for research use only. Not for human or veterinary use.*