Semax 10 mg

What is Semax?

Semax is a synthetic, linear heptapeptide from the sequence family of adrenocorticotropic hormone (ACTH) and thus belongs to the neuropeptide analogues of the melanocortin family. In databases and the scientific literature it also appears as ACTH(4-7)-Pro-Gly-Pro, ACTH(4-7)PGP or, in one-letter notation, MEHFPGP. No single receptor has so far been described in the literature as an established target.

Origin of the sequence

ACTH is a chain of 39 amino acids derived from the precursor protein pro-opiomelanocortin (POMC). Semax takes residues 4 to 7 from it, that is methionine, glutamic acid, histidine and phenylalanine, and extends them at the C-terminus with the tripeptide proline-glycine-proline (PGP). In the catalogue and in many publications Semax is listed as an “ACTH(4-10) analogue”. What is meant is a modified fragment: the ACTH section 4-10 reads Met-Glu-His-Phe-Arg-Trp-Gly, whereas after the phenylalanine Semax continues not with arginine, tryptophan and glycine but with PGP. The structurally exact notation is therefore ACTH(4-7)-Pro-Gly-Pro.

Structure and key data

• Sequence: Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP), free N-terminal amine and free C-terminal carboxylic acid
• Molecular formula: C37H51N9O10S
• Molar mass: 813.9 g/mol (calculated)
• CAS number: 80714-61-0
• PubChem CID: 9811102

Formula and mass apply to the free peptide. Counter-ions from synthesis and purification are not included.

Classification: Semax and Selank

Semax is often mentioned in the same breath as Selank, because both heptapeptides were designed on the same principle: a short natural fragment carries the ending Pro-Gly-Pro at its C-terminus. The starting sequences, however, have nothing to do with each other. Semax comes from a section of ACTH whose sequence is also contained in α-MSH; Selank goes back to the tetrapeptide tuftsin. Chemically, this shows for instance in the sulfur atom of methionine, which only Semax has, and in a mass difference of around 62 g/mol. Both peptides are also available together in the Semax + Selank set; the other sequences in this group are listed in the Neuropeptides category.

Research context

The published preclinical work on Semax is based predominantly on rodent and cell culture models. The focus is on gene expression in the neurotrophin system: studies look at the expression of the genes for BDNF (brain-derived neurotrophic factor), its receptor TrkB and NGF in the rat hippocampus and cortex. Further studies evaluate transcriptome and proteome data from brain tissue of experimental animal models. The findings describe these model systems only.

Analytics at GPeptides

Semax is regularly tested by an independent external laboratory. HPLC separates the heptapeptide from synthesis-related by-products such as truncated sequences; the purity value corresponds to the area share of the main peak in the chromatogram. Mass spectrometry confirms identity by comparing the measured mass with the value calculated from C37H51N9O10S. Because Semax contains methionine, a signal 16 Da heavier is informative here: it points to oxidised methionine (methionine sulfoxide). Published certificates of analysis are in the lab area, where products without an available document carry the note “pending”. How separation and mass determination work together is explained in the guide HPLC and mass spectrometry.