What is KPV?
At 342.44 this is among the smallest molecules in the catalog, and the molecular reference records all three residues explicitly: lysine, proline, and valine. The central proline forces a turn that makes the chain more conformationally defined than its length suggests, and the lysine side chain gives a positive charge at neutral pH. The molecule is unusually robust, with no oxidation prone residue and no disulfide.
The sequence is the carboxy terminal tripeptide of alpha melanocyte stimulating hormone. That parent hormone signals through melanocortin receptors, but the published literature on the fragment describes activity in cell models that does not appear to require them. Reported observations include reduced nuclear factor kappa B pathway signalling and lowered inflammatory cytokine expression in epithelial and immune cell cultures, and rodent colitis models have been used to examine mucosal inflammation markers in the animals studied (Dalmasso, 2008).
What is not settled is the entry route and target. Transport by the peptide transporter PepT1 has been proposed in intestinal epithelium, but the intracellular target remains unidentified.
Reconstitution & handling
The tripeptide dissolves rapidly and completely in sterile or bacteriostatic water, added slowly down the vial wall with a gentle swirl. The basic lysine side chain gives good aqueous solubility across the useful pH range and no co-solvent is required. Concentration is a plain division, so 2 mL added to a 10 mg vial gives 5 mg per millilitre.
Storage & stability
Sealed lyophilized vials are kept at -20 °C, protected from light and moisture, and equilibrated to room temperature before the stopper is pierced. Reconstituted solution is refrigerated at 2 to 8 °C, aliquoted into single use volumes, and protected from repeated freezing and thawing. This sequence is chemically among the more stable in the catalog, with no methionine, cysteine, or tryptophan to oxidise, so the practical limits in solution are microbial growth in unpreserved water and slow aminopeptidase activity.
How it's tested
Each lot is analysed by reversed phase HPLC at 214 and 220 nm, which is essential here because the sequence contains no aromatic residue and gives no usable signal at 280 nm. Retention is short for such a small polar peptide, so a shallow gradient resolves it from the solvent front. Mass spectrometry confirms identity against the theoretical mass of 342.44 from C16H30N4O4.