Nrf2 (69-84) peptide

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

Batch to batch variation of the purity

The Nrf2 (69-84) peptide, with the amino acid sequence AFFAQLQLDEETGEFL, corresponds to residues 69 to 84 of the human Nrf2 protein. This 16-mer peptide contains the critical ETGE motif, which is a high-affinity binding site for the Kelch domain of the Keap1 protein. Structural studies, including X-ray crystallography, reveal that this peptide adopts a conformation featuring two anti-parallel strands connected by overlapping type I β-turns when bound to Keap1. The glutamate residues within the ETGE motif, specifically E79 and E82, form multiple specific interactions with residues in the Kelch domain's binding pocket, such as R415 and R483, while the peptide backbone makes additional contacts involving E78, T80, and F83.

Biophysical analyses, including surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC), have characterized the interaction. The equilibrium dissociation constant (K_D) for the binding of this peptide to the Keap1 Kelch domain in solution is approximately 20-24 nM. Deletion studies indicate that the minimal Nrf2 peptide sequence required for maintaining high-affinity Keap1 binding is a 9-mer sequence, LDEETGEFL (residues 76-84). This shorter peptide retains a β-hairpin conformation stabilized by intramolecular hydrogen bonds and exhibits moderate binding affinity (K_D ~352 nM), which can be significantly enhanced by N-terminal acetylation to remove a positive charge.

• Chen Y, Inoyama D, Kong AN, Beamer LJ, Hu L. Kinetic analyses of Keap1-Nrf2 interaction and determination of the minimal Nrf2 peptide sequence required for Keap1 binding using surface plasmon resonance. Chem Biol Drug Des. 2011 Dec;78(6):1014-21. doi: 10.1111/j.1747-0285.2011.01240.x. Epub 2011 Oct 31. PMID: 21920027; PMCID: PMC3218206.

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.