Are Semax, MT-2 and KPV related?

Yes — all three are fragments or analogues of alpha-MSH, which is itself the first 13 residues of ACTH.

Do any of them overlap?

Semax and MT-2 share His-Phe at positions 6 and 7. KPV, at positions 11 to 13, is adjacent and does not overlap either.

Why do they behave so differently?

Because what each retains determines what it can do — MT-2 keeps the receptor-binding core, KPV keeps the C-terminal tail and discards that core.

Semax (ACTH Fragment Peptide)

Semax, MT-2 and KPV Are Pieces of the Same Sequence

JMWritten & reviewed by Jack Muncaster · Founder, UK PeptidesLast reviewed 2026-08-234 cited sources

Alpha-MSH is thirteen residues. Semax retains positions 4 to 7, MT-2 is built around a core corresponding to positions 6 to 9, and KPV is positions 11 to 13 exactly. Three separate product categories on this site are fragments of one sequence.

Key facts

Parent: alpha-MSH, 13 residues, 1,664.9 Da
Semax retains: Positions 4–7, Met-Glu-His-Phe
Semax replaces: Positions 8–10 with Pro-Gly-Pro
MT-2 core: His-D-Phe-Arg-Trp, positions 6–9
KPV: Lys-Pro-Val, positions 11–13
Overlap: Semax and MT-2 share His-Phe (6–7)
KPV: Adjacent and non-overlapping

The parent sequence

Alpha-MSH runs Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val, acetylated at the front and amidated at the end. Numbering those positions one to thirteen is what makes the fragment literature legible — every compound discussed here is described by which of those positions it keeps.

Where Semax sits

Semax is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues are positions 4 to 7 of the parent. What follows is not the parent's positions 8 to 10 — Arg-Trp-Gly — but Pro-Gly-Pro substituted in their place. So Semax keeps the front of the shared region and discards the part that follows it.

Research material referenced

Semax 10mg — third-party HPLC tested

View — £24.99

Where MT-2 sits

MT-2 is a cyclic heptapeptide whose core reads His-D-Phe-Arg-Trp, corresponding to positions 6 to 9, with norleucine standing in for the methionine position and D-phenylalanine replacing the L form. Those four residues are the recognised melanocortin receptor-binding core, which is why a compound built to engage those receptors is built around them.

Where KPV sits

KPV is Lys-Pro-Val — positions 11, 12 and 13, the C-terminal end of the parent, taken unmodified. It is the only one of the three that is an exact excerpt rather than an analogue.

What the map shows

Semax and MT-2 overlap at His-Phe, positions 6 and 7. KPV lies beyond both, adjacent and non-overlapping. The three compounds together cover most of the parent's second half, carved into pieces by three different research programmes pursuing three different questions — cognition, pigmentation and inflammation.

Why the pieces behave so differently

Because what each retains determines what it can do. MT-2 keeps the receptor-binding core and is built to engage melanocortin receptors. KPV keeps the C-terminal tail associated with anti-inflammatory activity and deliberately discards the receptor core. Semax keeps the front of the region and replaces what follows with a stability motif. Same parent, three different design intentions, three different molecules.

The regulatory position across all three

None of Semax, MT-2 or KPV holds a marketing authorisation from the MHRA, EMA or FDA. All are supplied here for laboratory research only, and no claim is made about any of them in relation to any condition in any person.

Quick reference

Compound	alpha-MSH positions	Relationship
Semax	4–7 retained	Analogue — 8–10 replaced by Pro-Gly-Pro
MT-2	6–9 as core	Analogue — cyclised, D-Phe, Nle
KPV	11–13	Exact excerpt

Extended research context

The Semax (ACTH Fragment Peptide) deep dive

Deep dive: what the Pro-Gly-Pro extension actually accomplishes

Semax is built from a four-residue fragment of ACTH with Pro-Gly-Pro appended, and that appendix does two separate jobs at once. Proline is the only proteinogenic amino acid whose side chain bonds back to its own backbone nitrogen, forming a ring that removes the amide hydrogen and locks rotation. Proteolytic enzymes generally need an extended, rotatable backbone at their active site, so bonds near proline are poor substrates for most of them — which is why proline-rich motifs recur throughout stabilised peptide design. The second job is subtractive: Pro-Gly-Pro occupies the positions where ACTH carries Arg-Trp-Gly, and those are the residues contributing to the parent hormone's adrenal-stimulating activity. One substitution therefore buys protease resistance and removes an unwanted pharmacology, which is unusually economical design.

Deep dive: the naming point worth getting right

Semax is near-universally described as an ACTH(4-10) analogue, and peer-reviewed paper titles use that phrase. Structurally it is not quite that. ACTH residues 4 to 10 are Met-Glu-His-Phe-Arg-Trp-Gly; Semax is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues match and the last three are wholly different — replacement rather than modification. PubChem, indexing by structure rather than design lineage, records it as ACTH(4-7) plus Pro-Gly-Pro. Neither name is wrong, but the loose one obscures the fact that the substituted segment is precisely the functionally consequential part.

Deep dive: reading an unevenly distributed evidence base

Semax's roughly 231 indexed records split along an unusual line. Mechanistic work — BDNF and trkB expression in rat hippocampus, transcriptomics in focal cerebral ischaemia, neurotrophin dynamics across brain regions — appears in international journals in English and can be assessed directly. Clinical work is concentrated in Russian-language publications, principally the Korsakov Journal of Neurology and Psychiatry, indexed by translated title and often without accessible English full text, much of it predating current standards for pre-registration and reporting. The honest position is that this is evidence which is difficult to verify independently, which is a different thing from evidence that is absent, and a different thing again from evidence that is established.

Research applications

▸Neurotrophin expression research (BDNF, NGF, TrkB, TrkA)
▸Neuroprotection and cerebral ischaemia models
▸Study of proline-stabilised peptide design
▸Comparative work on ACTH fragments without steroidogenic activity
▸Transcriptomic profiling in rodent brain models

Handling checklist

✓Store lyophilised material cold, dry and protected from light
✓Expect methionine oxidation as the degradation route (+16 Da; only one Met, so not +32)
✓No reducing agent needed — the sequence contains no cysteine
✓Introduce diluent gently against the vial wall; swirl rather than shake
✓Aliquot to avoid repeated freeze-thaw cycles
✓Check whether a certificate reports net peptide content or gross salt weight

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Describing Semax as ACTH(4-10) without qualification

Fix: It shares only residues 4-7; Pro-Gly-Pro replaces Arg-Trp-Gly, and that replacement is the design's whole point.

✗ Treating Russian registration as equivalent to MHRA approval

Fix: Authorisations are jurisdictional and do not transfer. Semax has never been assessed by the MHRA, EMA or FDA.

✗ Reading a BDNF expression change as a demonstrated outcome

Fix: The studies measured gene and protein expression in rats. Expression is upstream of function and upstream again of any clinical claim.

✗ Assuming a named receptor exists

Fix: No primary receptor has been definitively established; the literature characterises downstream effects more confidently than the initiating event.

✗ Expecting ACTH-like adrenal effects

Fix: Semax does not stimulate adrenal steroidogenesis — the responsible residues were substituted out.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Frequently asked questions

Are Semax, MT-2 and KPV related?: Yes — all three are fragments or analogues of alpha-MSH, which is itself the first 13 residues of ACTH.
Do any of them overlap?: Semax and MT-2 share His-Phe at positions 6 and 7. KPV, at positions 11 to 13, is adjacent and does not overlap either.
Why do they behave so differently?: Because what each retains determines what it can do — MT-2 keeps the receptor-binding core, KPV keeps the C-terminal tail and discards that core.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

Written and reviewed by

Jack Muncaster · Founder, UK Peptides

Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate.

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