"Glow peptide" and "Klow peptide" are informal names used in the research supply market for two multi-peptide blends built around GHK-Cu. Neither name refers to a single compound, and neither has a CAS number of its own. This article explains what each blend is generally understood to contain, how they differ, and what to check when documenting a blended research material.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.
At a glance
- Name: Klow (multi-peptide research blend)
- Synonyms: Klow blend; related to the Glow blend
- Sequence: Not applicable - blend of separate peptides (see composition below)
- Molecular formula: Not applicable to a blend
- Molecular weight: Not applicable to a blend
- CAS number: None - each component has its own CAS number
- Form: Lyophilised powder
- Storage: 2-8°C, dark, upright - do not freeze. Keep sealed until use.
Compound Cave supplies Klow 80mg at >99% purity by HPLC. Check the product page and label for the exact component list and quantities of the batch you receive, as blend formulations are not standardised across the market.
What is a peptide blend?
A peptide blend is a single vial containing two or more separately synthesised peptides, combined and lyophilised together. Each component keeps its own identity: blending does not create a new molecule. That is why blends have no single sequence, formula, molecular weight or CAS number. Instead, a blend is described by its list of components and the quantity of each.
Blends raise particular analytical questions. An HPLC chromatogram of a blend shows several peaks, one or more per component, and the purity of each component should ideally be assessed against its own reference. Mass spectrometry should show the expected mass for each component. Our guide on how to read a peptide certificate of analysis covers the basics.
The Glow blend
The Glow blend is generally described in the market as a three-component combination:
- GHK-Cu: the copper(II) complex of the tripeptide Gly-His-Lys, CAS 89030-95-5.
- BPC-157: a 15-amino-acid synthetic peptide (GEPPPGKPADDAGLV), CAS 137525-51-0.
- TB-500: a synthetic peptide related to a fragment of thymosin beta-4, CAS 885340-08-9.
Each of these components has been investigated separately in the laboratory literature. GHK-Cu has been studied in fibroblast cultures and rodent tissue repair models since the 1980s, as covered in our GHK-Cu copper peptide overview. BPC-157 and thymosin beta-4 related peptides have been investigated in a range of rodent models, summarised in our BPC-157 and TB-500 research overview. We are not aware of a substantial peer-reviewed literature on the combined blend itself.
The Klow blend
The Klow blend is generally described as the Glow combination with a fourth component added:
- GHK-Cu
- BPC-157
- TB-500
- KPV: the tripeptide Lys-Pro-Val, corresponding to the C-terminal sequence of alpha-melanocyte-stimulating hormone.
KPV has been investigated in its own right in cell culture and rodent models of inflammation, including models of intestinal inflammation. More detail is in our article on KPV peptide. The "K" in Klow is commonly taken to refer to KPV, although the naming is informal and not defined by any standard.
How Glow and Klow differ
Composition
The core difference is the presence of KPV in Klow. Glow is usually three components; Klow is usually four. Because the total vial content is shared across the components, the proportion of each peptide in a Klow vial may also differ from its proportion in a Glow vial.
Ratios are not standardised
There is no pharmacopoeial or industry standard for either blend. Different suppliers may use different ratios of the components and different total quantities. For research records, the composition stated on the specific product and batch is what matters, not the generic name.
Appearance
Both blends contain GHK-Cu, so both are typically blue to violet in colour. The intensity of colour depends on the proportion of GHK-Cu in the blend. The other components are colourless, so a blend with a smaller share of GHK-Cu will look paler. Colour is a useful first observation but cannot confirm the presence or proportion of the colourless components.
Analysis
A Klow chromatogram has an additional component compared with Glow. KPV is a very small, polar tripeptide, so it may elute early under reversed-phase conditions. As with GHK-Cu alone, acidic HPLC conditions can partially strip copper from the complex, which affects how the GHK-Cu component appears. Our article on handling copper peptides in the lab discusses this alongside storage.
Points to check when sourcing a blend
- The named components and the quantity of each per vial.
- The total content per vial and how it is stated.
- How purity was measured and whether it refers to the blend or to individual components.
- Whether mass spectrometry data covers every component.
- Storage guidance, since the most sensitive component determines the conditions needed.
Storage
Blends inherit the storage needs of their most sensitive component. Our guidance for Klow is 2-8°C, dark, upright, not frozen, and kept sealed until use. The copper complex adds sensitivity to strong chelators and reducing agents. General principles are covered in how to store lyophilised peptides.
View Klow 80mg in the catalogue.
Frequently asked questions
What is the difference between Glow and Klow peptide blends?
Both are informal names for blends built around GHK-Cu. Glow is generally described as GHK-Cu, BPC-157 and TB-500. Klow is generally described as the same three plus the tripeptide KPV.
Does a peptide blend have a CAS number?
No. A blend is a physical mixture of separate peptides. Each component has its own CAS number, but the blend as a whole does not.
Why are Glow and Klow blends blue?
Both contain GHK-Cu, the copper(II) complex of Gly-His-Lys, which is blue to violet. The other components are colourless.
Are blend ratios the same between suppliers?
Not necessarily. There is no standard formulation for either blend, so the component list and quantities stated for the specific product should always be checked.
Is there published research on the blends themselves?
We are not aware of a substantial peer-reviewed literature on these blends as combinations. The individual components have each been investigated separately in laboratory models.
References
- Maquart FX, Pickart L, Laurent M, Gillery P, Monboisse JC, Borel JP. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Letters, 1988.
- Pickart L, Margolina A. Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. International Journal of Molecular Sciences, 2018.
- Brzoska T, Luger TA, Maaser C, Abels C, Böhm M. Alpha-melanocyte-stimulating hormone and related tripeptides: biochemistry, antiinflammatory and protective effects in vitro and in vivo. Endocrine Reviews, 2008.
For laboratory research use only. Not for human or veterinary use. See our research use only policy.