What should a KPV supplier Australia list on a Lys-Pro-Val identity CoA?
Identity documentation should open with the chemical name H-Lys-Pro-Val-OH, the single-letter sequence KPV, and an explicit statement that the intended analyte is the free tripeptide rather than a longer melanocortin fragment. Literature naming is consistent with that three-residue string: Elliott and co-workers refer to MSH 11–13 KPV (PMID:15102092); Bonfiglio and co-workers refer to the COOH-terminal tripeptide α-MSH(11–13) (PMID:16965771); Kannengiesser and co-workers describe KPV as a melanocortin-derived tripeptide (PMID:18092346). Those citations support nomenclature only. They do not replace a batch-specific spectrum. Catalogue synonyms never override the lot-specific formula, mass and retention time.
The CoA should report molecular formula C16H30N4O4 for the neutral free base, the calculated monoisotopic mass, and the observed m/z for [M+H]+ under named electrospray conditions. Lysine can carry a second charge, so [M+2H]2+ may appear; both ions should be assigned with a stated mass-error window. A sentence such as MS consistent with structure without theoretical mass, observed mass and analyser type is not an identity test. Where tandem MS is supplied, fragment ions should distinguish Lys-Pro-Val from composition-matched sequence isomers (for example Lys-Val-Pro), which a parent mass alone cannot separate.
Chromatographic identity requires a retained principal peak, not an absorbance envelope at the void. The method print-out should list column chemistry, particle size, mobile-phase composition, ion-pair reagent if used, gradient, flow, temperature, detection wavelength and retention time. KPV has no aromatic side chain, so detection is at peptide-bond wavelengths (typically 210–220 nm); a 280 nm chromatogram is not informative for this sequence. Vial label, CoA lot number and dispatch note must agree on sequence, salt form and lot before Australian tracked dispatch from local stock.
How can HPLC-MS distinguish authentic KPV from melanocortin-related analogues?
Catalogue proximity is not chemical identity. Gatti and co-workers examined (CKPV)2, a cysteine-containing dimeric analogue whose elemental composition, thiol chemistry and molecular mass are incompatible with unmodified H-Lys-Pro-Val-OH (PMID:16413580). A CoA that lists a KPV-related peptide without sequence, formula and observed m/z cannot exclude that analogue class. Brzoska and co-workers discuss α-MSH-related peptides with emphasis on C-terminal message residues and structure beyond a classical pharmacophore (PMID:21222263). That structural context is a caution: a supplier may ship a longer fragment, an N-acetylated peptide or a C-terminal amide while still using melanocortin language on a storefront.
Termini must be written on the CoA. Many melanocortin research sequences are N-acetylated and C-amidated; research KPV is commonly the free N-terminus and free carboxylic acid. Those mass shifts are easy to miss on a low-resolution scan if theoretical mass is not calculated for the claimed termini.
Reversed-phase retention is an orthogonal filter. Unmodified KPV is small and polar; a cysteine-containing dimer, a lysine-alkylated analogue or a longer melanocortin fragment will not share both retention time and extracted-ion chromatogram. Laboratories should require an extracted-ion chromatogram at theoretical [M+H]+ of KPV, a full-scan spectrum of the principal peak, and a note that major ions are inconsistent with (CKPV)2. Sequence isomers (Lys-Val-Pro, Pro-Lys-Val) are isobaric with KPV and may co-elute on a generic C18 gradient; tandem MS ions that locate proline, or another orthogonal method, are the appropriate request when the purchase specifies Lys-Pro-Val.
Which related-substance peaks belong on a KPV related-substances chromatogram?
For a three-residue peptide the impurity map is short but not trivial. Process-related species include deletion peptides (Lys-Pro, Pro-Val, Lys-Val), residual protected intermediates such as N-Fmoc species from Fmoc solid-phase synthesis, incompletely cleaved lysine protecting groups, and residual coupling additives. Proline-containing sequences can generate diketopiperazine by-products from dipeptide esters; those cyclic species have distinct masses and usually different retention. None of these is identified by a lone 99% purity figure.
A usable related-substances section states detection wavelength, integration threshold, whether peaks below a reporting limit are omitted, and whether purity is area percent at 214 nm or a weight-percent value after response-factor correction. For KPV, low-wavelength area percent is typical because there is no aromatic reporter. Diode-array peak-purity indices are weak when the analyte and many peptide impurities share the peptide-bond chromophore; a ratiogram that looks pure can still hide a co-eluting deletion peptide. Mass-selective inspection of the principal peak is the more honest orthogonal check: extract the KPV [M+H]+, look for unresolved ions at deletion-peptide masses, and record unidentified m/z values. Keep unidentified ions on the report.
Acceptance language is method-specific. An unidentified-peak reporting threshold (for example 0.10 area percent) only means something when the gradient resolves polar impurities from the void and when the on-column sample amount places that impurity above the limit of quantification. A CoA that shows a cropped single peak with no expanded baseline, no blank overlay and no secondary m/z list is not a related-substances test.
Why do counter-ion and net peptide content dominate a tripeptide certificate?
Mass-fraction arithmetic is unforgiving at three residues. Trifluoroacetate or acetate counter-ions, residual water and residual process solvents can constitute a substantial percentage of the lyophilised solid. A vial labelled with a nominal milligram quantity without net peptide content (NPC), a counter-ion assay and a water value does not tell the laboratory how much Lys-Pro-Val is present.
The CoA should name the salt form (free base, acetate, trifluoroacetate) and report measured counter-ion content, typically by ion chromatography, 19F nuclear magnetic resonance for TFA, or a validated equivalent. Amino-acid analysis or another peptide-specific assay should support NPC, stating whether the result is as-is solid or anhydrous, counter-ion-free peptide. Karl Fischer titration belongs in the same packet because water dilutes NPC and varies between lyophilisation lots. Residual-solvent results by headspace gas chromatography complete the mass balance when synthesis used DMF, dichloromethane, acetonitrile or ether washes.
Without that mass balance, HPLC purity can mislead. A chromatogram may show 99 area percent at 214 nm while a large fraction of the solid mass is TFA and water, which are invisible in that chromatogram. Two Australian suppliers quoting the same purity and the same nominal fill are not equivalent if one reports high TFA and the other reports acetate with NPC by amino-acid analysis. Ask for the calculation: vial mass × NPC × chromatographic purity, with each term defined. Salt form should appear on the vial label, CoA and invoice so chromatographic method development uses the correct counter-ion.
What lot-traceability documents should Australian laboratories require before ordering?
Traceability links a physical vial to a set of analytical files. The lot number on the label must match the CoA, the chromatogram header, the mass-spectrum header and the packing list. If a supplier cannot produce that four-way match before purchase, the laboratory is buying an untraceable solid. For Australian research purchasing, the lot on the CoA should be the lot in local stock, with tracked dispatch referencing that lot rather than a warehouse alias.
The batch report should identify HPLC method code and version, column identity, mobile-phase recipes, system-suitability results (retention window, tailing factor, blank cleanliness), analysis date, instrument identifier and the data-processing method. The MS section should identify the instrument, calibration approach, acquisition range and theoretical versus observed mass. Attachments matter: a percentage typed into a table without a chromatogram is not reviewable. Request a file that shows the full time axis, including the void, and the spectrum of the principal peak.
A retain from the same lot allows a later HPLC-MS re-run if identity is questioned; a supplier who cannot identify the synthesis batch cannot support that query. Retest dates on research CoAs are analytical control dates for the documented solid. Invoices and packing lists should carry H-Lys-Pro-Val-OH, salt form, lot number and a research-use statement. Multi-vial orders should share one lot with a single CoA or itemise lots per vial. Mixed lots under one product name without split CoAs defeat trend analysis.
How do lysine modifications, hydrogels and nanoparticle constructs change the KPV specification?
Not every published KPV material is the free tripeptide. Songok and co-workers described reductive glycoalkylation of the lysine residue, a covalent modification that changes mass and chromatographic behaviour relative to unmodified Lys-Pro-Val (PMID:29953505). A CoA for free KPV should show the unmodified [M+H]+ and should not be silent on lysine derivatisation. If a catalogue item is a glycoalkylated analogue, the identity table must use the modified formula, and residual unmodified KPV becomes a related substance.
Matrix constructs are a second specification fork. Xiao and co-workers reported hyaluronic acid-functionalised nanoparticle constructs carrying the tripeptide (PMID:28143741). Sun and co-workers described a self-cross-linked hydrogel of cysteamine-grafted γ-polyglutamic acid incorporating KPV (PMID:34547895). Those papers are formulation-chemistry references showing KPV as a guest in a polymer system. They are not CoAs and they do not make a lyophilised free-peptide lot equivalent to a nanoparticle or hydrogel lot. Construct testing includes polymer identity, particle or gel characterisation, peptide loading and residual free peptide.
Australian buyers should require the catalogue to declare which item is sold: H-Lys-Pro-Val-OH as a lyophilised solid; a defined lysine-modified analogue; or a formulated construct. HPLC area percent of a tripeptide peak does not measure polymer mass. Request the structural drawing, termini and theoretical mass of the claimed analyte before comparing suppliers. Unexplained hexose-type mass shifts, thiol-containing masses consistent with CKPV motifs, or undefined complexed material should be reclassified.
Order Kpv with documentation
If this guide helped you evaluate Kpv for laboratory work, the next step is documented supply: research-grade stock from Australian warehouses, Express tracked shipping, and batch documentation with every order.
Open the Kpv card on the ClaraScience shop for current stock and add-to-cart, or request wholesale access when you need bulk restocks and tier pricing.
Frequently asked questions
Is HPLC purity alone enough to qualify a KPV supplier in Australia?
No. Purity is an area-percent result at a stated wavelength and does not prove the Lys-Pro-Val sequence, termini, salt form or net peptide content. Ask for theoretical and observed mass, sequence, counter-ion, water and a lot-matched chromatogram before comparing suppliers. The CoA is a chemistry document for research material only.
What mass-spectrometry result should appear for unmodified KPV?
The CoA should list formula C16H30N4O4 for the neutral free tripeptide, the calculated monoisotopic mass, and the observed [M+H]+ (and [M+2H]2+ if present) with analyser type and mass error. Tandem fragments that locate proline distinguish Lys-Pro-Val from isobaric sequence isomers. A qualitative MS-consistent line without numbers is insufficient.
How does (CKPV)2 differ from KPV on a certificate of analysis?
(CKPV)2 is a cysteine-containing dimeric analogue, not H-Lys-Pro-Val-OH. It has a different formula, mass and thiol-related chemistry. A KPV CoA should state the Lys-Pro-Val sequence and show an extracted-ion result at the KPV mass, not a generic melanocortin label. If the intended analyte is the dimer, the CoA must use the dimer structure instead.
Why must TFA or acetate be quantified on research KPV lots?
Short peptides can carry a large mass fraction of counter-ion. HPLC area percent does not detect TFA or acetate. Ion chromatography or an equivalent assay, plus net peptide content and water, allows conversion from vial mass to peptide mass. Salt form should match the vial label and invoice for method development.
What should match before tracked dispatch from Australian local stock?
Sequence name, salt form and lot number should be identical on the vial, CoA, chromatogram header and packing list. The dispatch record should cite that lot. Multi-vial orders should share one lot or itemise lots. Missing attachments (full chromatogram, mass spectrum) mean the lot is not reviewable.
Do nanoparticle or hydrogel KPV materials use the same CoA as the free tripeptide?
No. Polymer constructs require polymer identity, loading and residual free-peptide tests. A free-peptide HPLC purity value does not measure polymer mass. Confirm whether the catalogue item is H-Lys-Pro-Val-OH, a lysine-modified analogue, or a formulated construct before comparing documentation.
References
- PMID:15102092 — alpha-Melanocyte-stimulating hormone, MSH 11-13 KPV and adrenocorticotropic hormone signalling in human keratinocyte cells — J Invest Dermatol — 2004
- PMID:16965771 — Effects of the COOH-terminal tripeptide alpha-MSH(11-13) on corneal epithelial wound healing: role of nitric oxide — Exp Eye Res — 2006
- PMID:18092346 — Melanocortin-derived tripeptide KPV has anti-inflammatory potential in murine models of inflammatory bowel disease — Inflamm Bowel Dis — 2008
- PMID:21222263 — Terminal signal: anti-inflammatory effects of α-melanocyte-stimulating hormone related peptides beyond the pharmacophore — Adv Exp Med Biol — 2010
- PMID:16413580 — Inhibitory effects of the peptide (CKPV)2 on endotoxin-induced host reactions — J Surg Res — 2006
- PMID:29953505 — Structural modification of the tripeptide KPV by reductive "glycoalkylation" of the lysine residue — PLoS One — 2018
- PMID:28143741 — Orally Targeted Delivery of Tripeptide KPV via Hyaluronic Acid-Functionalized Nanoparticles Efficiently Alleviates Ulcerative Colitis — Mol Ther — 2017
- PMID:34547895 — Self-Cross-Linked Hydrogel of Cysteamine-Grafted γ-Polyglutamic Acid Stabilized Tripeptide KPV for Alleviating TNBS-Induced Ulcerative Colitis in Rats — ACS Biomater Sci Eng — 2021
Research use only
This article is provided for laboratory research and educational purposes only. Products referenced are not for human or veterinary use. ClaraScience makes no therapeutic, medical, or efficacy claims, and nothing here constitutes medical advice.
