KPV: Three Residues of α-MSH, With or Without the Amide

KPV is Lys-Pro-Val, the last three residues of α-MSH. Free acid or amide, how KdPT differs, and what its small preclinical literature consists of.

Published 29 October 2026

KPV is three amino acids long: lysine, proline, valine. It is short enough that it seems there could be nothing to get wrong. In fact the name covers at least two molecules, and there is a third, closely related tripeptide that turns up beside it in the same papers. This page sets out which molecule "KPV" refers to, how it relates to the hormone it was cut from, and what its research literature consists of.

The molecule#

All three residues are the ordinary L-forms. The free-acid formula, weight and CAS number match the reference records at ChemicalBook, which lists it as "α-MSH (11-13) (free acid)", and Wikipedia's chemical data box, which gives PubChem CID 125672. We worked out the amide's figures from the sequence ourselves. We could not find a registry entry for it that we trust, so no CAS number is given for it.

When people say "KPV" without qualification, they usually mean the free acid, and that is the form most chemical catalogues list under the name.

Where it comes from#

KPV is the last three residues of α-melanocyte-stimulating hormone (α-MSH). α-MSH is a 13-residue peptide cut from a larger precursor, pro-opiomelanocortin (POMC), the same precursor that gives rise to ACTH. According to UniProt entry P01189, the human α-MSH sequence is:

Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2

So Lys-Pro-Val sit at positions 11, 12 and 13, which is where the label "α-MSH (11–13)" comes from. UniProt records two modifications at the ends of α-MSH: an acetyl group on the first serine and an amide on the final valine.

That second detail is the main point of this page. In the parent hormone, the valine at the end of KPV is amidated. The KPV most often sold and catalogued is the free acid. The two differ by about one dalton (342.4 against 341.5). A mass spectrum can tell them apart, but a quick glance at one may not. Neither form is more "correct". They are different compounds, and a certificate should say which one it describes.

Some early papers say they used "α-MSH (11–13)" without stating the C-terminus. If the form matters to a piece of work, the methods section or the supplier's specification has to settle it.

Names that get used loosely#

• "KPV" and "α-MSH (11–13)". These are often treated as identical. Strictly, the natural fragment is the amide and the catalogue compound is usually the acid.
• "The active part of α-MSH." You will often see this phrase. It summarises a hypothesis from the early literature, not a structural fact, and α-MSH research involves other regions of the hormone too.
• KdPT. This is a different tripeptide: Lys-D-Pro-Thr, also written [D-Pro194]-IL-1β (193–195), with registry number 117027-34-6 (NLM MeSH). It is based on a sequence from interleukin-1β, not from α-MSH. Its proline is the D-form and its last residue is threonine, not valine. It turns up in the same papers as KPV because the same groups studied both (Brzoska et al., 2008). Lys-Pro-Thr weighs about 344.4, two daltons more than KPV, and mass spectrometry cannot tell D-proline from L-proline.
• D-amino-acid variants. A Lys-Pro-Val made with any D-residue is a separate compound too, with exactly the same mass. Unless a source says otherwise, "KPV" means all three residues in the L-form, and confirming that needs a chiral method or the manufacturer's synthesis records.

How the literature began#

The research history starts with α-MSH itself. By the late 1980s, James Lipton's group in Dallas had been studying α-MSH's effects on fever and on the permeability of small blood vessels. In 1989 Hiltz and Lipton asked whether the C-terminal tripeptide alone had comparable activity. They tested α-MSH (11–13) in a mouse model of chemically induced ear swelling and measured the swelling (Hiltz & Lipton, 1989, FASEB J). That paper is the usual starting point for KPV as a research compound in its own right.

The second centre of work was Münster, in Germany. Thomas Luger, Markus Böhm, Tomasz Brzoska and colleagues studied α-MSH and its fragments in skin and immune-cell biology. Their 2008 review in Endocrine Reviews surveys α-MSH, KPV and KdPT together. It notes that the tripeptides do not share α-MSH's pigmentary activity, which was one reason for interest in them (Brzoska et al., 2008). A Münster gastroenterology group, working with the same authors, tested KPV in two mouse colitis models: one induced chemically with dextran sodium sulphate (DSS), and one in which colitis develops after a T-cell transfer. They measured body weight, tissue histology and myeloperoxidase activity, an enzyme marker of neutrophil infiltration. They also used mice lacking a functional melanocortin-1 receptor, to ask whether that receptor was required (Kannengiesser et al., 2008, Inflamm Bowel Dis).

The third and most-cited strand comes from Didier Merlin's laboratory at Emory University in Atlanta. It approached KPV through transport biology. The group's 2008 Gastroenterology paper studied whether KPV enters intestinal epithelial cells through PepT1, a transporter for di- and tripeptides. They worked in human intestinal epithelial cell lines (Caco2-BBE and HT29-Cl.19A) and a T-cell line, measured NF-κB reporter activity and related signalling, and ran two mouse colitis models (Dalmasso et al., 2008).

The nanoparticle papers#

Much of what followed from the Merlin group is about delivery, not the peptide itself. The question was how to get a small, water-soluble tripeptide to a particular region of the mouse intestine.

• In 2010 the group loaded KPV into polymer nanoparticles held in an alginate–chitosan hydrogel designed to break down in the colon. They tested the particles in colon cell cultures and in the DSS mouse model (Laroui et al., 2010, Gastroenterology). The authors reported comparable effects at a concentration 12,000-fold lower than with unformulated KPV. That is a statement about the delivery system as much as about the peptide.
• In 2017 the group coated KPV-loaded nanoparticles with hyaluronic acid, about 272 nm across, embedded in a hydrogel. They tested uptake in colonic epithelial cells and macrophages, then measured tissue damage and TNF-α levels in a mouse colitis model (Xiao et al., 2017, Mol Ther).

The point for a newcomer is the one our earlier post on gut peptide research makes. These are studies of engineered formulations, and what they measured describes the formulation in a mouse. They are not evidence about a vial of unformulated powder.

What kinds of studies exist, and how many#

Put together, the KPV literature has four parts:

• cell-culture work on intestinal epithelial cells, immune cells and skin cells, measuring signalling pathways and cytokine release;
• rodent studies, mostly mouse colitis models, plus some skin and other models from the α-MSH tradition;
• delivery-system studies that use KPV as the cargo in nanoparticle and hydrogel designs;
• reviews, which are numerous for a literature this size.

It is a small body of work. The papers that study KPV itself number in the dozens, not the hundreds, and the parent hormone's literature is far larger. A handful of groups produced most of it: Lipton's in Dallas, Luger and Böhm's in Münster, and Merlin's in Atlanta.

We have found no published human clinical trial of KPV. It is not a licensed medicine in the United Kingdom or, as far as we can establish, anywhere else. The record is preclinical from start to finish.

What to check on a certificate#

For a three-residue peptide, identity comes down to a small number of masses:

• Near 342.4: KPV free acid.
• Near 341.5: KPV amide, the form found at the end of α-MSH.
• Near 344.4: Lys-Pro-Thr, which includes KdPT and is a different peptide.
• No mass reported: a purity figure alone cannot tell you which of these is in the vial.

Salt form adds a further layer. KPV has two free amino groups, one on the lysine side chain and one at the N-terminus, so it is commonly made as an acetate or trifluoroacetate salt. The counter-ion adds weight that is not peptide. Our guides on what an HPLC purity figure means and how to verify a certificate cover how to read these documents. Our post on Kisspeptin-10 describes the same amide-or-acid question for a longer peptide. Ask about batch documentation before ordering.

Handling#

KPV is supplied as a lyophilised powder. As a very small, water-soluble peptide it needs nothing beyond the general approach. See how to reconstitute research peptides and how to store research peptides.

What this page does not claim#

Nothing here concerns what KPV does in a person or an animal outside the studies cited. Those studies are described as history: who did the work, in which models, and what they measured. The question this page answers is which molecule the name refers to, and it has a definite answer.

In our catalogue#

• KPV: tripeptide Lys-Pro-Val

Supplied for laboratory research use only. Not for human or veterinary use.

Pioneer Research Peptides — UK supplier of research peptides for laboratory use. Ask about batch documentation before you order.

For laboratory research use only — not for human consumption. 18+.