KLOW Peptide Blend: Composition and Research Overview

KLOW is a lyophilized four-peptide research blend supplied as an 80 mg vial: 10 mg BPC-157, 10 mg TB-500 (thymosin beta-4), 10 mg KPV and 50 mg GHK-Cu. Each component has its own preclinical literature, but the blend itself is a formulation convenience, not a compound with its own body of published studies. It is the GLOW blend plus 10 mg of KPV.

Per-vial composition

Equal masses don't mean equal numbers of molecules. The four components differ by more than an order of magnitude in molecular weight:

The smaller molecules are therefore present in far greater molar numbers than thymosin β-4, even at the same mass. Keep this in mind when you interpret analytical data from the blend.

The four components

BPC-157

BPC-157 is a 15-residue synthetic peptide (Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val, C₆₂H₉₈N₁₆O₂₂) described by its originating group as a gastric peptide, formed in the gastric mucosa and stable in human gastric juice [1]. Its effects on blood vessels, including angiogenesis and VEGF, nitric oxide and FAK signaling, have been reviewed [2]. In endothelial cells it activated a Src–Caveolin-1–eNOS pathway [3]. It is not an approved drug. See the full BPC-157 research overview.

TB-500 (thymosin beta-4)

Thymosin β-4 is a 43-residue, N-terminally acetylated peptide and one of the main intracellular G-actin–sequestering molecules [4]. It has been studied in models of coronary vessel development and epicardial progenitor differentiation [5]. The "TB-500" name has historically also been applied to a short synthetic fragment; the TB-500 in our blends is the full-length 43-residue peptide. See TB-500 and thymosin beta-4.

GHK-Cu

GHK (Gly-His-Lys) is a tripeptide identified in human plasma [6] that binds copper(II) with high affinity and has been examined as a carrier of copper into cultured cells [6]. As the copper complex, it has been studied for its effects on collagen synthesis in fibroblast cultures [7]. GHK-Cu makes up most of the KLOW vial by mass. See GHK-Cu: the copper tripeptide in research.

KPV

KPV (Lys-Pro-Val, C₁₆H₃₀N₄O₄) is the C-terminal tripeptide of α-melanocyte-stimulating hormone (α-MSH residues 11–13), a linear 13-residue peptide. Its conformations have been modeled by molecular dynamics [8]. KPV has been studied in epithelial cell signaling models, including NF-κB pathway work. In human bronchial epithelial cells it inhibited NF-κB signaling, which the author linked to interference with p65RelA nuclear import [9]. In human keratinocytes it did not raise cyclic AMP but did trigger intracellular calcium signals. Whether it acts through the melanocortin-1 receptor remains unresolved [10]. KPV is the only component KLOW has that GLOW lacks.

Why researchers look at combinations

These components were studied separately, in different models, by different groups. In the published work they map onto partly overlapping areas: angiogenesis and nitric-oxide signaling (BPC-157), actin dynamics and cell migration (thymosin β-4), extracellular matrix synthesis (GHK-Cu) and epithelial NF-κB and calcium signaling (KPV). A blend lets a lab put all four into one test article. As far as we know, though, no peer-reviewed study has characterized this four-component blend as a single test article. Interaction effects, relative contributions and in-vitro stability of the mixture are open questions. Findings from single-compound papers are not findings about the blend.

Reading a KLOW certificate of analysis

A blend COA is different from a single-peptide COA. In a reverse-phase HPLC run, the four components elute at different retention times because they differ widely in size and hydrophobicity. The chromatogram should show a separate main peak for each, not a single peak. For KPV, a published stability-indicating method identified lysyl-proline diketopiperazine as the main degradation product under stress conditions [11], so that species is worth looking for. Check how the lab defines the purity figure (per component or combined), and confirm that the mass spectrometry section identifies each component. Our guides to reading a certificate of analysis and HPLC purity cover the underlying methods.

Expect the lyophilized cake to be blue, not white. The copper(II) complex in GHK-Cu is blue, and at 50 mg it dominates the color of the vial. A blue appearance entry on a KLOW COA is normal.

Batch documents for every lot are listed in the COA registry.

Storage and handling

KLOW is laboratory material. Store the lyophilized vial at −20 °C, away from light and moisture, and let it reach room temperature before opening so condensation doesn't form on the cold powder. Once reconstituted, keep the solution at 2–8 °C and avoid repeated freeze–thaw cycles. A multi-component solution's stability window depends on its least stable member. Document your own handling conditions.

Product links

• KLOW 80 mg blend
• KLOW blend, Made in USA
• Without KPV: GLOW blend / GLOW, Made in USA. See KLOW vs GLOW.

Common questions

Is KLOW the same as GLOW?

No. GLOW has the same BPC-157, TB-500 and GHK-Cu content but no KPV, so it is a 70 mg vial instead of 80 mg. The comparison is covered in KLOW vs GLOW.

Is KLOW an approved drug?

No. KLOW is a research blend, and none of its components is an approved drug.

References

1. Sikiric P, et al. Stable gastric pentadecapeptide BPC 157-NO-system relation. Curr Pharm Des. 2014. PubMed
2. Seiwerth S, et al. BPC 157 and blood vessels. Curr Pharm Des. 2014. PubMed
3. Hsieh MJ, et al. Modulatory effects of BPC 157 on vasomotor tone and the activation of Src-Caveolin-1-endothelial nitric oxide synthase pathway. Sci Rep. 2020. PubMed
4. Huff T, et al. beta-Thymosins, small acidic peptides with multiple functions. Int J Biochem Cell Biol. 2001. PubMed
5. Smart N, et al. Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization. Nature. 2007. PubMed
6. Pickart L, et al. Growth-modulating plasma tripeptide may function by facilitating copper uptake into cells. Nature. 1980. PubMed
7. Maquart FX, et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 1988. PubMed
8. Chavatte P, et al. Conformational analysis of tripeptide Ac-Lys-Pro-Val-NH2, COOH-terminal sequence of alpha-MSH. J Pharm Pharmacol. 2001. PubMed
9. Land SC. Inhibition of cellular and systemic inflammation cues in human bronchial epithelial cells by melanocortin-related peptides: mechanism of KPV action and a role for MC3R agonists. Int J Physiol Pathophysiol Pharmacol. 2012. PubMed
10. Elliott RJ, et al. alpha-Melanocyte-stimulating hormone, MSH 11-13 KPV and adrenocorticotropic hormone signalling in human keratinocyte cells. J Invest Dermatol. 2004. PubMed
11. Pawar KR, et al. Stability-indicating HPLC assay for lysine-proline-valine (KPV) in aqueous solutions and skin homogenates. Biomed Chromatogr. 2015. PubMed