Catalogue / KPV
KPV
Also written as Lys-Pro-Val, alpha-MSH 11-13.
The C-terminal tripeptide of alpha-melanocyte stimulating hormone, at 342 daltons one of the smallest peptides routinely submitted for analysis.
| Molecular formula | C16H30N4O4 |
| Average mass | 342.43 Da |
| Monoisotopic mass | 342.2267 Da |
| Residues | 3 |
| Termini | C-terminal free acid |
| Class | Repair and regenerative peptides |
| Determination | Peptide analysis, catalogue compound |
| Price | 341 USD |
Computed at build time from the composition shown on this page, not transcribed from a supplier datasheet.
KPV has an average molecular weight of 342.43 daltons and a monoisotopic mass of 342.2267 daltons. Identity is confirmed by matching the measured deconvoluted mass to that figure, and purity is reported separately by reversed-phase chromatography at 214 nm. The two numbers answer different questions and neither substitutes for the other.
| One letter | KPV |
| Three letter | Lys-Pro-Val |
| Modifications | C-terminal free acid |
The formula and both masses in the table above are derived from this sequence and these terminal modifications. A reader who believes a figure is wrong can check the composition rather than take the number on trust, which is the point of publishing it this way.
A sequence is not an identity result. It is the expected composition against which a measured mass is compared, and the comparison is what appears on the certificate.
| Charge | m/z |
|---|---|
| [M+1H]+ | 343.234 |
| [M+2H]2+ | 172.121 |
These are the ions an electrospray source is expected to produce for a neutral mass of 342.2267 daltons, computed from the monoisotopic mass and the proton mass. They are what a raw spectrum should show before deconvolution.
A report that gives only a deconvoluted mass without the charge states it was derived from cannot be checked. Deconvolution is a calculation, and a calculation whose inputs are not shown is an assertion.
| At this molecular weight the trifluoroacetate counter-ion can account for a quarter of the delivered mass. A purity percentage without a counter-ion determination overstates the delivered peptide substantially. |
| The peptide is barely retained on a standard C18 column and can elute in the void, where nothing is separated from anything. Polar-retentive stationary phase or ion-pairing is required. |
| Low mass places it near the low-mass cutoff of some ion traps, where transmission is poor and the base peak is not the molecular ion. |
Every compound fails in its own way. A generic peptide method applied without regard to these specifics produces a number that looks like a result and is not one.
Fragment peptides derived from larger endogenous proteins. Because they are fragments, a supplier can ship a shorter truncation that still looks correct on a chromatogram.
LC-MS identity with deconvolution, purity by RP-HPLC at 214 nm, and net peptide content where the delivered milligram figure matters.
Where the delivered milligram figure matters rather than the percentage, net peptide content by combustion analysis and water by Karl Fischer are added, and the certificate carries a closed mass balance instead of a single purity number.
| LC-MS identity | Measured mass |
| RP-HPLC purity | Area at 214 nm |
| Net peptide content | Milligrams |
| Water content | Karl Fischer |
| Counter-ion | Ion chromatography |
| Bacterial endotoxins | USP <85> |
What is the molecular weight of KPV?
The average molecular weight is 342.43 daltons and the monoisotopic mass is 342.2267 daltons, computed from the sequence KPV shown on this page. Both figures are calculated rather than transcribed, so they can be checked against the stated composition.
How is KPV tested for purity and identity?
LC-MS identity with deconvolution, purity by RP-HPLC at 214 nm, and net peptide content where the delivered milligram figure matters. Purity describes the chromatographable fraction only and is not the same quantity as the peptide mass delivered per vial.
What goes wrong when KPV is analysed?
At this molecular weight the trifluoroacetate counter-ion can account for a quarter of the delivered mass. A purity percentage without a counter-ion determination overstates the delivered peptide substantially.
What does KPV analysis cost at ANALYTON?
Peptide analysis, catalogue compound is priced at 341 US dollars, covering the determinations described on this page. Content, safety and elemental determinations are ordered alongside and are priced separately on the price list.
Other compounds in this class
Updated 2026-09-01. Masses computed at build, not transcribed.