Learn
KPV Peptide
Technical Compound Reference | Orion Peptides Learning Library
KPV is a short synthetic tripeptide composed of three amino acid residues: lysine, proline, and valine.
Its amino acid sequence is written as Lys-Pro-Val, or KPV using standard one-letter notation.
The sequence corresponds to the three C-terminal residues of alpha-melanocyte-stimulating hormone (α-MSH), a 13-amino-acid peptide belonging to the melanocortin family.
Unlike many larger synthetic research peptides, KPV does not contain a lipid conjugate, disulfide bridge, or chemically modified backbone in its standard free-acid form.
Its structure is defined by two peptide bonds, three L-amino acid residues, a free N-terminal amino group, and a C-terminal carboxylic acid.
The compound is identified by CAS number 67727-97-3 and the molecular formula C₁₆H₃₀N₄O₄.
KPV is particularly relevant to research involving short-peptide chemistry, stereochemical identification, peptide transport, conformational analysis, chromatography, and mass spectrometry.
This technical reference examines its sequence, molecular properties, chemical forms, laboratory characterization, and structural relationship to longer melanocortin peptides.
1. KPV Molecular Identity
| Property | Technical information |
|---|---|
| Compound name | KPV |
| Chemical name | L-Lysyl-L-prolyl-L-valine |
| Alternative designation | α-MSH (11–13), MSH (11–13) |
| CAS number | 67727-97-3 |
| PubChem CID | 125672 |
| Molecular formula | C₁₆H₃₀N₄O₄ |
| Average molecular weight | 342.43 g/mol |
| Monoisotopic mass | Approximately 342.2267 Da |
| Number of amino acids | 3 |
| Sequence | Lys-Pro-Val |
| One-letter sequence | KPV |
| Molecular configuration | Linear tripeptide |
| Amino acid stereochemistry | L-Lys, L-Pro, L-Val |
| N-terminal group | Free amino group |
| C-terminal group | Carboxylic acid |
| Number of peptide bonds | 2 |
| Disulfide bonds | None |
| Structural origin | C-terminal sequence of α-MSH |
These data describe the free-acid KPV reference structure. Counterion-containing materials, including acetate salts, have separate chemical compositions.
2. Three Amino Acids, Three Different Chemical Characteristics
Although KPV contains only three residues, each contributes a different structural feature.
The order is important because changing the sequence would produce a different peptide even if the amino acid composition remained the same.
Lysine (K): The Basic Residue
Lysine occupies the N-terminal position.
Its side chain contains an additional amino group.
This group can carry a positive charge in aqueous environments depending on pH.
The N-terminal amino group also participates in the peptide’s acid-base chemistry.
The presence of these basic groups influences molecular charge and interactions with other chemical species.
Proline (P): The Conformationally Restricted Residue
Proline is the central amino acid.
Unlike most standard amino acids, proline has a side chain that forms a ring connected to its backbone nitrogen.
This cyclic arrangement restricts certain peptide backbone conformations.
As a result, proline-containing peptides can exhibit structural behavior different from peptides containing more flexible amino acids.
Valine (V): The Hydrophobic C-Terminal Residue
Valine is the final residue in the KPV sequence.
Its side chain contains a branched hydrocarbon group.
This gives valine relatively hydrophobic characteristics.
In the free-acid KPV reference structure, valine also carries the terminal carboxylic acid group.
Residue Summary
| Residue | Position | Main chemical feature |
|---|---|---|
| Lysine | 1 | Basic amino-containing side chain |
| Proline | 2 | Cyclic side chain restricting backbone geometry |
| Valine | 3 | Branched hydrophobic side chain |
Together, these residues determine the charge, shape, and physicochemical behavior of KPV.
3. How KPV Relates to Alpha-MSH
KPV corresponds to residues 11–13 of alpha-melanocyte-stimulating hormone.
Alpha-MSH is a 13-residue peptide derived through processing of the precursor protein proopiomelanocortin, commonly abbreviated POMC.
Its sequence is:
Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂
The final three residues are:
Lys-Pro-Val
This sequence provides the structural relationship between KPV and the parent hormone.
Does Isolated KPV Have the Same Terminal Groups as Alpha-MSH?
Not necessarily.
The final valine residue of mature α-MSH is C-terminally amidated.
The standard free-acid KPV reference is written:
H-Lys-Pro-Val-OH
This structure has a free N-terminus and a C-terminal carboxylic acid.
An independently synthesized amidated analog would have a different chemical identity and molecular mass.
Is KPV the Same as Alpha-MSH?
No.
KPV contains three amino acids.
Alpha-MSH contains thirteen.
The parent peptide also contains additional amino acid regions and terminal modifications absent from free-acid KPV.
These differences can affect molecular recognition, conformation, enzymatic susceptibility, and experimental behavior.
Does KPV Automatically Activate Melanocortin Receptors?
No such conclusion should be drawn solely from its sequence origin.
Classical melanocortin receptor recognition involves additional structural features of α-MSH, particularly its central His-Phe-Arg-Trp region.
Isolated KPV lacks that complete motif.
Research involving KPV has examined other cellular pathways and peptide-transport mechanisms.
It should not automatically be assigned the full receptor pharmacology of α-MSH or Melanotan I.
4. KPV and the Chemistry of Two Peptide Bonds
A tripeptide contains three amino acid residues joined by two peptide bonds.
In KPV, the bonds connect:
Lys–Pro and Pro–Val
Peptide bonds form between the carboxyl group of one amino acid and the amino group of the next.
The resulting covalent linkage is an amide bond.
Why Are Peptide Bonds Important?
Peptide bonds form the backbone of peptides and proteins.
Their chemical properties influence molecular geometry and stability.
A peptide bond generally has restricted rotation because of partial double-bond character.
Proline and Cis-Trans Isomerization
Peptide bonds involving proline can adopt different configurations.
These configurations are commonly called cis and trans.
The relative populations of these forms depend on the molecular structure and surrounding conditions.
Because KPV contains proline, its conformational chemistry is an interesting subject for experimental analysis.
However, a particular cis-trans distribution should not be asserted without supporting measurements.
Does KPV Form a Cyclic Peptide?
No.
KPV is a linear tripeptide.
The ring within proline is part of the individual amino acid residue and does not cyclize the entire peptide backbone.
5. What Determines KPV’s Molecular Charge?
KPV contains several ionizable groups.
These include the N-terminal amino group, lysine side-chain amino group, and C-terminal carboxylic acid.
The ionization state of these groups changes according to the surrounding pH.
Why Does Charge Matter?
Molecular charge can influence interactions with water, chromatographic materials, charged surfaces, and other molecules.
Changes in pH can therefore alter the peptide’s observed behavior.
Is KPV Always Positively Charged?
Not under every chemical condition.
Its net charge depends on the protonation states of its ionizable groups.
The exact charge distribution must be considered relative to pH and the chemical environment.
KPV and Solubility
KPV has several polar and ionizable functional groups.
These features contribute to its interactions with aqueous environments.
However, actual solubility depends on the material form, temperature, concentration, solution composition, and pH.
A universal solubility claim should not be made without defining the tested conditions.
6. KPV Free Acid vs KPV Acetate
A chemical distinction often overlooked in peptide catalogs is the difference between a peptide’s free-acid structure and its acetate-containing form.
The commonly referenced KPV molecule is:
H-Lys-Pro-Val-OH
Its molecular formula is:
C₁₆H₃₀N₄O₄
Its average molecular weight is approximately 342.43 g/mol.
A defined KPV acetate reference includes an additional acetic acid component.
Chemical Form Comparison
| Property | KPV free acid | KPV acetate reference |
|---|---|---|
| PubChem CID | 125672 | 90474670 |
| Molecular formula | C₁₆H₃₀N₄O₄ | C₁₈H₃₄N₄O₆ |
| Molecular weight | 342.43 g/mol | Approximately 402.5 g/mol |
| Peptide sequence | KPV | KPV |
| Additional component | None in reference formula | Acetic acid |
| Identical chemical composition? | No | No |
The difference is important when interpreting molecular weight and material quantity.
Does Acetate Change the Amino Acid Sequence?
No.
The KPV backbone remains Lys-Pro-Val.
However, the counterion-associated material has a different overall composition.
Is Every KPV Acetate Sample Exactly the Same?
Not necessarily.
Commercial peptide preparations may have different counterion content and residual moisture.
Analytical documentation should therefore identify the actual material form rather than assuming a fixed composition from a generic label.
7. KPV Transport in Experimental Cell Models
One area of published KPV research involves the peptide transporter PepT1.
PepT1, also known as SLC15A1, is a membrane transport protein capable of transporting certain dipeptides and tripeptides.
Because KPV is a tripeptide, researchers have examined whether it can interact with peptide-transport systems.
What Did the 2008 Research Examine?
Dalmasso and colleagues investigated KPV uptake in experimental intestinal epithelial and immune-cell systems.
The research reported PepT1-associated transport of KPV under the conditions studied.
This provided evidence that certain membrane transport systems can recognize the peptide.
Why Is This Relevant to Molecular Research?
Transport studies help researchers distinguish between extracellular peptide availability and intracellular peptide exposure.
A compound’s presence outside a cell does not automatically establish that it enters the cell.
Transporter activity can influence the amount of a peptide detected in an intracellular experimental system.
Does PepT1 Transport Establish All Cellular Activities of KPV?
No.
Transport is one molecular event.
It does not independently identify every downstream signaling pathway or establish a primary receptor for KPV.
Primary reference: Dalmasso G. et al. (2008), PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation.
8. Characterizing KPV with Mass Spectrometry
Mass spectrometry is widely used to identify small peptides through molecular mass measurements.
For KPV, the theoretical free-peptide molecular formula provides a reference for expected mass-related signals.
Average Mass vs Exact Mass
KPV has an average molecular weight of approximately 342.43 g/mol.
Its monoisotopic mass is approximately 342.2267 Da.
These values describe different mass conventions.
Average mass reflects natural isotopic abundances.
Monoisotopic mass uses a specified set of isotopes.
Why Is the Observed Ion Mass Different?
Mass spectrometers measure mass-to-charge ratios rather than simply reporting the neutral molecular weight.
KPV can form protonated or other ionic species during ionization.
For example, a singly protonated KPV molecule has a different mass from the neutral reference structure.
Therefore, analytical interpretation must account for the ion detected.
Does a Matching Mass Prove the KPV Sequence?
Not by itself.
Molecular mass identifies elemental composition-related information.
Different molecular structures can sometimes share the same molecular formula.
Sequence-supporting analytical methods may be required to distinguish KPV from other isomeric structures.
9. HPLC Characterization of a Short Tripeptide
High-performance liquid chromatography separates chemical components according to their interactions with the chromatographic system.
KPV can be investigated using suitable chromatographic methods.
However, short polar peptides can present different separation challenges from longer, more hydrophobic peptides.
Why Does Peptide Length Matter?
Longer peptides often contain more functional groups influencing retention.
KPV contains only three residues.
Its limited size and relatively polar chemical character may produce weak retention under some conventional reversed-phase conditions.
The method must be appropriate for the target compound.
Reversed-Phase Chromatography
Reversed-phase HPLC uses a relatively nonpolar stationary phase.
Peptide retention depends on the relationship between molecular characteristics and mobile-phase composition.
KPV’s charged groups and short sequence can influence this behavior.
Alternative Chromatographic Approaches
Depending on the analytical objective, researchers may consider methods such as hydrophilic interaction chromatography or ion-exchange chromatography.
These techniques use different separation mechanisms.
Their suitability must be established through method development and validation.
Can HPLC Establish Purity?
HPLC can provide chromatographic purity information under defined conditions.
However, a reported peak-area purity is not automatically equivalent to total mass purity or quantitative peptide content.
10. Chemical Stability and Potential Degradation
KPV contains two peptide bonds and several functional groups that can participate in chemical reactions under suitable conditions.
Its relatively small size does not make it universally stable.
Peptide Bond Hydrolysis
Hydrolysis can cleave peptide bonds.
For KPV, cleavage may produce shorter peptide fragments or individual amino acids.
The reaction rate depends on the chemical environment.
Conformational Changes
The proline residue can influence local backbone geometry.
Changes in conformational populations do not necessarily alter the primary molecular formula.
However, they may influence some experimental observations.
Oxidation
KPV does not contain methionine, cysteine, or tryptophan.
This means several common oxidation-sensitive side chains are absent.
Nevertheless, it would be inaccurate to conclude that KPV is immune to every oxidation-related or other degradation reaction.
Temperature, Moisture and pH
Chemical reaction rates and peptide stability may be influenced by temperature, moisture, solution pH, and formulation composition.
Validated stability studies are needed to establish material-specific shelf life.
Is Lyophilized KPV Automatically Stable?
No.
Lyophilization reduces water content and may improve stability for certain materials.
However, stability depends on residual moisture, packaging, temperature, and other conditions.
A powder’s physical appearance does not establish its chemical integrity.
11. What Should a KPV Certificate of Analysis Include?
A Certificate of Analysis records the analytical tests associated with an identified sample or batch.
For a short peptide such as KPV, important information includes molecular identity, chemical form, peptide content, and chromatographic findings.
| COA component | Scientific purpose |
|---|---|
| Compound name | Identifies KPV |
| Amino acid sequence | Confirms the intended Lys-Pro-Val reference |
| CAS number | Chemical identification |
| Batch number | Material traceability |
| Chemical form | Free acid or defined salt |
| Expected molecular mass | Reference for mass analysis |
| Observed mass spectrometry | Molecular identity-related findings |
| Chromatogram | Separation profile |
| Chromatographic purity | Purity result under the analytical method |
| Peptide assay | Amount of KPV, if measured |
| Counterion analysis | Associated counterion content, if tested |
| Water content | Residual moisture, if tested |
| Laboratory identification | Testing organization |
| Testing date | Date of analysis |
Why Is the Chemical Form Important?
A mass measurement for KPV free acid should not be confused with the calculated mass of an acetate-containing material.
The COA should identify which structure or composition serves as the analytical reference.
Can HPLC Alone Verify the Complete Structure?
No.
Chromatographic retention provides separation-related information.
Complementary analysis may be needed to support molecular composition, sequence, or stereochemical identity.
Why Does Batch Traceability Matter?
Different batches can contain different impurities or associated components.
A batch-specific COA helps connect measured results to the actual material examined.
12. How KPV Differs from Other Melanocortin-Related Peptides
KPV is structurally related to α-MSH and Melanotan I because its sequence occurs near their C-termini.
However, this relationship does not make the molecules interchangeable.
KPV vs Melanotan I
Melanotan I is a 13-residue modified α-MSH analog.
It contains a longer peptide backbone and nonstandard amino acid substitutions.
KPV is a three-residue peptide containing only lysine, proline, and valine.
Their molecular masses, structural features, and experimental pharmacology differ.
KPV vs Melanotan II
Melanotan II is a synthetic cyclic heptapeptide.
It contains a lactam bridge and is engineered for melanocortin receptor activity.
KPV is linear and does not contain a lactam bridge.
KPV also lacks the complete central melanocortin pharmacophore present in Melanotan II.
Molecular Comparison
| Feature | KPV | Melanotan I | Melanotan II |
|---|---|---|---|
| Peptide length | 3 | 13 | 7 |
| Structural configuration | Linear | Linear | Cyclic |
| Relationship to α-MSH | C-terminal fragment | Modified full-length analog | Short cyclic analog |
| Disulfide linkage | No | No | No |
| Lactam bridge | No | No | Yes |
| Principal structural distinction | Lys-Pro-Val tripeptide | Nle4 and D-Phe7 substitutions | Cyclic melanocortin pharmacophore |
13. KPV in Multi-Peptide Research Mixtures
KPV is included in some commercially defined peptide mixtures.
One example is the KLOW formulation, which contains KPV alongside GHK-Cu, BPC-157, and TB-500.
Why Is Component Identity Important?
A mixture does not have one universal molecular formula or molecular weight.
Each peptide retains a separate chemical identity.
KPV should therefore be characterized independently when evaluating a multi-component material.
Can a Blend Be Identified with One Mass Spectrometry Signal?
Not reliably.
Different components have different masses and may require different analytical conditions.
A complete blend characterization should investigate the intended compounds separately.
Does KPV Research Establish the Properties of KLOW?
No.
Results obtained from isolated KPV do not automatically establish the chemical or biological behavior of a formulation containing several additional peptides.
Chemical compatibility, component concentrations, and stability must be examined for the actual mixture.
14. Frequently Asked Technical Questions About KPV
What is KPV?
KPV is a linear tripeptide composed of lysine, proline, and valine.
What does KPV stand for?
KPV represents the standard one-letter amino acid abbreviations for Lys-Pro-Val.
How many amino acids are in KPV?
Three.
What is the molecular formula of KPV?
C₁₆H₃₀N₄O₄.
What is the molecular weight of KPV?
Approximately 342.43 g/mol for the free-acid peptide.
What is the CAS number?
67727-97-3.
What is the PubChem CID?
What is the amino acid sequence?
Lys-Pro-Val, abbreviated KPV.
Is KPV a cyclic peptide?
No. It is a linear tripeptide.
Does KPV contain a disulfide bridge?
No. The sequence contains no cysteine residues.
What is the relationship between KPV and α-MSH?
KPV corresponds to the final three amino acid residues of α-MSH.
Is KPV the same as Melanotan I?
No. Melanotan I is a modified 13-residue peptide.
Is KPV the same as Melanotan II?
No. Melanotan II is a chemically different cyclic heptapeptide.
What is the role of proline in KPV?
Proline introduces conformational restrictions because its side chain forms a ring connected to the backbone nitrogen.
Does KPV have a free C-terminal group?
The standard free-acid reference contains a C-terminal carboxylic acid.
Is KPV acetate the same as free-acid KPV?
No. The acetate-containing form has a different overall composition.
What does PepT1 mean?
PepT1 is a membrane-associated transporter capable of transporting certain dipeptides and tripeptides.
Has KPV been studied in peptide transport experiments?
Yes. Published research has investigated PepT1-associated KPV uptake in experimental cellular systems.
What does mass spectrometry measure for KPV?
It measures mass-to-charge ratios of ionized molecular species.
Can HPLC measure KPV purity?
HPLC can provide chromatographic purity information when a suitable method is used.
Is a 99% HPLC purity result the same as 99% peptide content?
No. Chromatographic purity and quantitative peptide content are different measurements.
Can KPV undergo degradation?
Yes. Its chemical stability depends on the material and experimental conditions.
Does KPV have a universal storage temperature?
No. Storage requirements should be supported by stability data for the specific material and formulation.
What should a KPV COA show?
It should report the intended chemical identity and the actual analytical findings associated with a specific batch.
15. Scientific References and Chemical Databases
KPV Chemical Identity
PubChem: MSH (11–13), CID 125672
Reference information: Molecular formula, molecular weight, amino acid sequence, CAS number, and structural representation.
KPV Acetate Reference
PubChem: L-Lysyl-L-prolyl-L-valine acetate, CID 90474670
Reference information: Acetate-containing chemical form, elemental composition, and molecular weight.
Experimental Peptide Transport Research
Dalmasso G. et al. (2008)
PepT1-Mediated Tripeptide KPV Uptake Reduces Intestinal Inflammation.
Journal: Gastroenterology.
Technical relevance: PepT1-associated peptide transport, cellular uptake experiments, and KPV characterization in biological systems.
https://doi.org/10.1053/j.gastro.2007.10.026
Alpha-MSH Fragment Chemistry
Catania A. et al. (2008)
Alpha-Melanocyte-Stimulating Hormone and Related Tripeptides: Biochemistry, Antiinflammatory and Protective Effects In Vitro and In Vivo, and Future Perspectives for the Treatment of Immune-Mediated Inflammatory Diseases.
Journal: Endocrine Reviews.
Technical relevance: α-MSH-derived tripeptide chemistry, peptide structure and structure-activity relationships.
FDA Chemical Characterization
FDA Pharmacy Compounding Advisory Committee Materials (July 2026)
Technical relevance: KPV free-acid chemical identity, physicochemical information, material characterization, and regulatory evaluation.
Conclusion
KPV is a chemically defined three-amino-acid peptide with the sequence Lys-Pro-Val.
Its structure corresponds to the C-terminal portion of α-MSH but differs substantially from the complete parent peptide and related synthetic melanocortin analogs.
The molecular architecture contains two peptide bonds, a conformationally restricted proline residue, ionizable functional groups, and a free C-terminal carboxylic acid.
These characteristics make KPV relevant to research involving short-peptide chemistry, molecular charge, peptide transport, chromatographic separation, and mass spectrometric identification.
Accurate laboratory documentation requires distinguishing free-acid KPV from acetate-containing forms and separating theoretical molecular properties from batch-specific analytical findings.
Technical research notice: This article is intended for scientific education and laboratory research reference only. It does not provide dosing, administration, reconstitution, or personal-use instructions. KPV is not an FDA-approved drug, and chemical characterization does not establish the suitability of independently supplied material for human or veterinary use.
