KPV

1 Identity

Synthetic tripeptide corresponding to residues 11-13 of alpha-melanocyte-stimulating hormone. Free acid specified. Not a melanocortin receptor ligand by structure: it lacks the His-Phe-Arg-Trp core that melanocortin receptor binding requires, so it is not filed with the melanocortin ligands in this catalog. No CAS number is asserted for this article. Not synonyms, and each a separate article with a separate mass: the C-terminal amide H-Lys-Pro-Val-NH2 (C16H31N5O3, 341.46 average).

Sequence

H-Lys-Pro-Val-OH; one-letter KPV, the free acid, three residues. All-L, entirely proteinogenic. Free N-terminal alpha-amine, free lysine epsilon-amine, free C-terminal carboxylic acid. No amidation, no acetylation, no acylation, no lipidation, no PEGylation, no disulfide (there is no cysteine), no non-proteinogenic residue and no D-residue. Two protonatable sites, the N-terminal alpha-amine and the Lys side-chain amine, so mono- and bis-salts both occur and the stoichiometry is a stated attribute rather than an assumption. The company specification is the free acid, named by residue and C-terminus on the purchase order and confirmed at release; the C-terminal amide is a different article and is carried here as a named, limited impurity.

Molecular formula

C16H30N4O4 (free acid). C-terminal amide C16H31N5O3. Mono-acetate C18H34N4O6; bis-acetate C20H38N4O8; mono-trifluoroacetate C18H31F3N4O6; bis-trifluoroacetate C20H32F6N4O8. Governing degradant cyclo(Lys-Pro) C11H19N3O2 with co-released free valine C5H11NO2.

Average mass

342.440 Da (C16H30N4O4), on IUPAC 2021 abridged conventional atomic weights. Listings commonly print 342.43; the formula gives 342.440, and the spread is an atomic-weight revision rather than a discrepancy. Salt forms: mono-acetate 402.49; bis-acetate 462.54; mono-trifluoroacetate 456.46; bis-trifluoroacetate 570.49, of which 40.0 percent of the gross weight is counterion. On a 342 Da peptide the counterion is not a rounding error: a 10 mg gross fill of the bis-trifluoroacetate contains about 6.0 mg of peptide. Degradants: cyclo(Lys-Pro) 225.29; free valine 117.15. C-terminal amide 341.46.

Monoisotopic mass

342.22671 Da neutral (C16H30N4O4). [M+H]+ 343.23399; [M+2H]2+ 172.12063; [M-H]- 341.21943. C-terminal amide 341.24269 neutral, [M+H]+ 342.24997, which is 0.98 Da lighter than the free acid. Cyclo(Lys-Pro) 225.14773. The monoisotopic value is stated to five decimal places because the amide sits 0.98 Da away and three decimal places is not enough resolution to argue about.

Salt / variant note

This is the worked example for name collision in this catalog: one alias, alpha-MSH(11-13), resolves to two chemically different molecules at two different institutional suppliers. (1) free acid H-Lys-Pro-Val-OH, C16H30N4O4, 342.44 average / 342.22671 monoisotopic, the article one institutional supplier ships. (2) C-terminal amide H-Lys-Pro-Val-NH2, C16H31N5O3, 341.46 / 341.24269, the article a second institutional supplier ships under the title "alpha-Melanocyte Stimulating Hormone (11-13)", with no "amide" in the product name. The two differ by 0.98 Da, are not resolved by ordinary reversed-phase retention, and a purchase order reading "alpha-MSH(11-13)" and nothing more is a coin flip between them. (3) KdPT, Lys-D-Pro-Thr, C15H28N4O5, 344.41 / 344.20597, a different sequence carrying a D-proline, 1.97 Da heavier than the free acid, and the molecule to which the human ulcerative-colitis literature that circulates under the KPV name actually belongs; its formula and both its masses are stated so the mix-up can be caught on a certificate rather than only in marketing copy. (4) Salt forms, which move gross fill weight by up to 40 percent: mono-acetate 402.49, bis-acetate 462.54, mono-TFA 456.46, bis-TFA 570.49. (5) The governing degradant cyclo(Lys-Pro), C11H19N3O2, 225.29 / 225.14773, formed with loss of free valine (117.15), moisture- and temperature-accelerated. (6) Sequence permutations of Lys, Pro and Val, namely PKV, VKP, KVP, PVK and VPK, all have formula C16H30N4O4 and are isobaric with the target to every decimal place; only MS/MS sequencing separates them, so the certificate for this article requires MS/MS b/y sequencing and accurate mass alone does not discharge identity here. (7) A separate consumer-format article sharing only the name: the same three letters are sold as oral capsules at microgram strengths, which is not a research article in any sense.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists and is entirely preclinical and analytical; the evidence grade is D. What exists, by study type and identifier. Rabbit study of alpha-MSH(11-13) (Richards 1984). Animal-model studies of alpha-MSH-family peptides (Hiltz 1990). Preclinical work on PepT1 (SLC15A1) transport of the tripeptide, published in Gastroenterology and independently highlighted in post-publication review (Dalmasso 2008). Preclinical rodent colitis-model work with hyaluronic-acid-functionalized nanoparticle delivery (Xiao 2017). Pharmaceutical-sciences delivery and analytical literature: transdermal iontophoretic delivery across microporated human skin ex vivo (Pawar 2017) and a stability-indicating HPLC assay in aqueous solution and skin homogenates (Pawar 2014). In-vitro keratinocyte work (Sung 2025). Structural and conformational characterization of Ac-Lys-Pro-Val-NH2 (Chavatte 2001). Melanocortin-system structure-activity and selectivity work involving the KPV motif (Nyberg 2025). Human interventional literature: none identified for this article. No registered controlled human trial of the tripeptide was identified on ClinicalTrials.gov, and FDA's published statement, content current 22 April 2026, is that it has not identified any human exposure data on drug products containing KPV administered via any route. The human ulcerative-colitis material that circulates under this name reports KdPT, Lys-D-Pro-Thr, a different peptide, in a conference abstract (Kucharzik 2014).

4 Storage & specification

Storage

White lyophilized or crystalline powder, acetate salt, in a screw-cap amber borosilicate vial with a PTFE-lined closure. This is a laboratory-chemical presentation, non-sterile, with no sterility claim and no stoppered-and-crimped injection format. Store at -20 degrees C plus or minus 5 degrees C, tightly closed and desiccated, protected from light. Moisture control is the operative requirement rather than a general precaution: water accelerates N-terminal diketopiperazine formation, which is this molecule's governing degradation route, so a desiccant sachet travels in the secondary pack, the label carries a close-immediately-after-weighing instruction, and the sealed vial is equilibrated to ambient temperature before opening so that atmospheric moisture does not condense onto the cake. Two basic sites make the salt hygroscopic. Reconstituted solution is aliquoted single-use and held at -80 degrees C; repeated freeze-thaw is not permitted on a peptide whose principal degradant forms in water.

Shelf life

Provisional retest interval 24 months from QA release at -20 degrees C plus or minus 5 degrees C, desiccated, stated as provisional pending the company's own stability data. A mandatory 6-month interim stability pull runs on each of the first three commercial lots, assaying specifically for cyclo(Lys-Pro) and free valine rather than for total related substances, because a slow diketopiperazine drift is invisible inside an unspecified-impurity bucket. Full protocol ICH Q1A(R2)-style: 12 months real time with pulls at 0, 3, 6, 9 and 12 months at the labeled condition, plus 6 months accelerated at 40 degrees C / 75 percent relative humidity. If the accelerated arm shows diketopiperazine growth above 0.5 percentage points absolute, the routine interval is cut to 12 months and the labeled condition moves to -80 degrees C before any extension is considered. A retest date is printed on every vial, first-expiry-first-out is enforced against that date and not against receipt date, material passing retest is re-dated for a further 12 months and material failing is destroyed with the destruction recorded.