KPV vs GHK-Cu: Sequence, Mass and Structure Compared

KPV vs GHK-Cu compares two different tripeptides. KPV is Lys-Pro-Val, C16H30N4O4, 342.43 g/mol, CAS 67727-97-3, with no metal in its formula. GHK-Cu is Gly-His-Lys bound to copper(II), C14H23CuN6O4⁺, 402.9 g/mol as the complex cation, CAS 89030-95-5. They share one residue, lysine, at opposite ends of the chain. This page compares composition and identity, and data for one compound do not transfer to the other.

KPV vs GHK-Cu at a glance

Source: PubChem CIDs 125672, 71587328 and 73587; references as numbered; charge counted from the ionisable groups; m/z values calculated from the formulas; search terms under “How large each literature is”.

Research materials: Vortex supplies both as lyophilised research reagents: KPV peptide 10mg and GHK-Cu 50mg. Lab reports: /coa/.

KPV vs GHK-Cu sequence: one shared residue

Both molecules are tripeptides, three residues joined by two peptide bonds. The tripeptide explainer sets out how that class is defined and written. Side by side, the two sequences have little in common:

Source: standard amino-acid structures.

Lysine is the only residue in both, in position 1 of KPV and position 3 of GHK. Neither is a variant of the other. A closer relative of GHK-Cu is the alanine analogue in AHK-Cu vs GHK-Cu, and the KPV peptide reference covers the capped and D-amino-acid forms of KPV.

Composition: a metal-free peptide vs a copper complex

This is the largest compositional difference. KPV’s formula holds carbon, hydrogen, nitrogen and oxygen only. GHK-Cu adds a copper(II) ion, which makes up about 15.8% of the complex cation by mass.

That copper is bound, not covalently built into the chain, and the bonding has been measured. At neutral pH, GHK forms a mononuclear 1:1 complex with copper(II), and its optical spectrum shifts at apparent pK values of 3.6, 9.2 and 11.4 [3]. In solution the complex is monomeric, and three nitrogen atoms hold the copper: the terminal amine, a deprotonated amide nitrogen and the histidine imidazole. In the solid state the complex is a dimer, and a labile carboxylate oxygen fills the fourth equatorial position [2]. Copper exchange between GHK molecules is fast [2]. The lysine side-chain amine joins the copper site only at alkaline pH and stays protonated near neutral pH [4].

The same material can therefore be described in more than one way, while KPV has one peptide formula. The GHK-Cu peptide reference covers the coordination work in full.

Mass and CAS: which number belongs to which form

Two mix-ups recur when these compounds are looked up.

• GHK-Cu has several formulas in circulation. C14H23CuN6O4⁺ is the complex cation, the record that CAS 89030-95-5 resolves to in PubChem. C14H22CuN6O4 is the neutral form, one proton fewer, and belongs to a different record. C14H24N6O4, CAS 49557-75-7, is the peptide without copper. Using 340.38 where 402.9 is meant changes a mass figure by about 18%.
• “KPV” alone is ambiguous. A PubChem name lookup for “KPV” resolved to an unrelated small molecule, CID 13294447, on 3 November 2026. CAS 67727-97-3 or CID 125672 reaches the tripeptide. The capped form Ac-KPV-NH2, CID 9209049, is 383.5 g/mol and is a different molecule.

Charge and chromatography of KPV and GHK-Cu

Near pH 7, KPV carries two protonated amines and one carboxylate, for a net charge of about +1. Free GHK reaches the same net charge from the same groups, with its histidine mostly uncharged. The copper complex is written as a +1 cation.

Both are small and polar, so both elute early on reversed-phase HPLC under acidic conditions. Selectivity for peptides depends on the column chemistry and the mobile phase [8], so retention figures do not carry between methods. Neither contains tryptophan or tyrosine, so UV detection reads mainly the peptide bonds at low wavelength. Copper(II) gives GHK-Cu its blue colour. KPV has no equivalent visible chromophore.

Stability chemistry: different weak points

Solid-state peptide reactions include deamidation, peptide-bond cleavage, oxidation and aggregation, with temperature, moisture and physical state among the factors involved [5]. The two sequences expose different reactions.

Source: references as numbered; ring-closure chemistry from reference 6, measured on a Phe-Pro model peptide, not on KPV.

In that model study, the rate of ring closure depended on pH, the unprotonated N-terminal amine was the more reactive form, and the residue before proline changed the rate [6]. Sealed-solid conditions are covered in the explainer on storing lyophilised peptides.

Telling KPV and GHK-Cu apart by LC-MS

The free peptides differ by only 2.04 Da, so a low-resolution reading deserves a second look. The formulas differ a great deal, though, and the fragment ions listed below do not overlap. Electrospray ionisation produces intact, often multiply charged ions [7], and acidic mobile phases can strip copper from the complex, so a GHK-Cu spectrum can show the free-peptide ion, a copper-containing ion or both.

Source: our calculation from monoisotopic masses. Fragment naming follows reference 9. These are expected values, not results from a report.

The copper pair comes from the natural ⁶³Cu and ⁶⁵Cu isotopes, and it marks an ion as copper-containing. The LC-MS peptide analysis explainer covers how these ions are read. Salt form is a separate question: most synthetic peptides leave purification in the presence of trifluoroacetic acid, and cationic peptides are obtained as trifluoroacetate salts unless the counter-ion is exchanged [10]. Neither intact mass nor a purity figure states the counter-ion.

KPV vs GHK-Cu lot reports

Vortex publishes lab reports at /coa/. A report describes the lot named on it and no other. On 3 November 2026 the page showed:

Source: the lot cards on /coa/ and the product pages, read 3 November 2026.

These are two lots, from two labs, by different methods, so the figures describe those lots and not the compounds. Net content is the mg figure the lab reports for the vial. The published KPV report page describes its analysis as RP-HPLC with UV detection, the GHK-Cu report gives one method line, HPLC with UV detection coupled with mass spectrometry, and neither the Freedom report nor page 1 of the ILS report names a counter-ion form. Neither report lists a separate copper-to-peptide assay, so this article draws no conclusion about copper content. The /coa/ page also shows a partner-facility report for GHK-Cu 100 mg, lot PS07-GHK100.

The identity methods also differ. An LC-MS result measures mass. An HPLC identity result compares retention, not mass, so the m/z values above are what an MS test would be expected to show for KPV rather than results from its report. The explainer on reading a peptide COA covers each field.

How large each literature is

A PubMed title-and-abstract search on 3 November 2026 returned 46 records for KPV with “peptide”, “tripeptide” or “MSH”, and 315 for GHK, glycyl-histidyl-lysine or glycyl-L-histidyl-L-lysine. The GHK figure includes some unrelated uses of the abbreviation. A record count measures how much has been published, and nothing further. The wider class is covered in the research peptides explainer.

Frequently asked questions

What is the difference between KPV and GHK-Cu?

KPV is the tripeptide Lys-Pro-Val with no metal in its formula, 342.43 g/mol. GHK-Cu is the tripeptide Gly-His-Lys bound to copper(II), 402.9 g/mol as the complex cation. The two share only lysine, in different positions.

Is KPV a copper peptide?

No. KPV’s formula, C16H30N4O4, contains no metal, and it has no histidine. GHK-Cu is the copper complex, with copper making up about 15.8% of the complex cation by mass.

Which CAS number belongs to GHK-Cu?

CAS 89030-95-5 is the copper complex cation, C14H23CuN6O4+, PubChem CID 71587328. The free GHK peptide without copper is CAS 49557-75-7, C14H24N6O4, 340.38 g/mol. KPV is CAS 67727-97-3.

How can a lab tell KPV from GHK by LC-MS?

The free peptides give [M+H]+ ions at m/z 343.23 for KPV and 341.19 for GHK, 2.04 Da apart. The b2 ion is m/z 226.16 for KPV and 195.09 for GHK. A copper-containing ion appears as a pair at m/z 402.11 and 404.11, expected for GHK-Cu only.

Research materials: KPV peptide 10mg and GHK-Cu 50mg are supplied as lyophilised research reagents. Published lab reports are at /coa/.

About this article: Written by the Vortex Research Editorial Team. Sources are peer-reviewed papers indexed in PubMed, each checked for title, journal and year and matched to its abstract. Reference 9 has no PubMed abstract and is cited for the naming convention it proposes. Formulas and masses are from PubChem; m/z values are calculated from the formulas. Lab report figures are from the published reports at /coa/.

References

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3. Freedman JH, Pickart L, Weinstein B, Mims WB, Peisach J. Structure of the glycyl-L-histidyl-L-lysine-copper(II) complex in solution. Biochemistry. 1982;21(19):4540-4544. PMID: 6291585. doi:10.1021/bi00262a004
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8. Mant CT, Cepeniene D, Hodges RS. Reversed-phase HPLC of peptides: assessing column and solvent selectivity on standard, polar-embedded and polar endcapped columns. J Sep Sci. 2010;33(19):3005-3021. PMID: 21038458. doi:10.1002/jssc.201000518
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10. Roux S, Zékri E, Rousseau B, Paternostre M, Cintrat JC, Fay N. Elimination and exchange of trifluoroacetate counter-ion from cationic peptides: a critical evaluation of different approaches. J Pept Sci. 2008;14(3):354-359. PMID: 18035848. doi:10.1002/psc.951

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