Discovery of a Head-to-tail Cyclic Peptide as the Keap1-Nrf2 Protein-protein Interaction Inhibitor with High Cell Potency

Lu MC, et al., 143:1578-1589, Eur J Med Chem, 2018

"The nuclear factor erythroid 2-related factor 2 (Nrf2) is a protein that plays a key role in the expression of antioxidant proteins, which provide protection against oxidative damage caused by inflammatory diseases. Enhancement of Nrf2 activity may be a new therapy for a number of inflammatory diseases. Kelch-like ECH-associated protein 1 (Keap1) is the principal regulator of Nrf2 activity. Described herein is the development of highly potent peptide inhibitors against the Keap1-Nrf2 protein-protein interaction using a head-to-tail cyclic strategy. The binding interaction between the ligand and the Keap1 Kelch domain was studied by using Bio-Layer Interferometry (BLI). A Pall ForteBio Octet RED96 instrument equipped with Super Streptavidin (SSA) Biosensor probes was used to perform BLI assays. Biotinylated Keap1 Kelch domain was immobilized onto SSA sensor tips. Subsequently, biotinylated protein loaded sensor tips were dipped in wells containing four concentrations of various peptide ligand samples for an association step, followed by a dissociation step in the buffer. Kinetic rate constants (kon and koff) and the equilibrium dissociation constants (KD) were determined for all binding interactions. Overall results of this study demonstrate the utility of head-to-tail cyclization method in developing peptide Keap1-Nrf2 inhibitors with high cell potency and provide useful insights into enhancing the cell potency of peptides in general.

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