KRFK peptide

• Handling and Storage of Synthetic Peptides
• Material Safety Data Sheets (MSDS)

Batch to batch variation of the purity

The KRFK peptide is a tetrapeptide derived from thrombospondin-1 (TSP-1), containing the amino acid sequence Lys-Arg-Phe-Lys. This peptide is known to activate latent transforming growth factor-β (TGF-β) by binding to the Leu-Ser-Lys-Leu (LSKL) sequence within the latency-associated peptide (LAP) of TGF-β. The interaction between KRFK and LSKL disrupts the binding between LSKL and the Arg-Lys-Pro-Lys (RKPK) sequence in mature TGF-β, thereby releasing the active form of TGF-β. This mechanism is particularly relevant for TGF-β2 activation, as TGF-β2 lacks the Arg-Gly-Asp (RGD) sequence required for integrin-mediated activation.

In vitro studies have demonstrated that KRFK can activate endogenous latent TGF-β produced by dendritic cells, leading to a downregulation of co-stimulatory molecules such as CD80 and promoting a tolerogenic phenotype. The peptide has also been shown to penetrate ocular surface tissues, including the cornea and conjunctiva, following topical application. These properties highlight the potential of KRFK as a modulator of immune responses, particularly in contexts where TGF-β activation is impaired.

• Soriano-Romaní L, Contreras-Ruiz L, López-García A, Diebold Y, Masli S. Topical Application of TGF-β-Activating Peptide, KRFK, Prevents Inflammatory Manifestations in the TSP-1-Deficient Mouse Model of Chronic Ocular Inflammation. Int J Mol Sci. 2018 Dec 20;20(1):9. doi: 10.3390/ijms20010009. PMID: 30577496; PMCID: PMC6337581.

Trifluoroacetic acid (TFA) is a common counterion from the purification process using High-Performance Liquid Chromatography (HPLC). The presence of TFA can affect the peptide's net weight, appearance, and solubility.

Impact on Net Weight: The TFA salt contributes to the total mass of the product. In most cases, the peptide content constitutes >80% of the total weight, with TFA accounting for the remainder.

Solubility: TFA salts generally enhance the solubility of peptides in aqueous solutions.

In Biological Assays: For most standard in vitro assays, the residual TFA levels do not cause interference. However, for highly sensitive cellular or biochemical studies, please be aware of its presence.