PADI3 Inhibitors

Chemical inhibitors of PADI3 include a range of compounds that target the enzyme's active site or essential cofactors to impede its catalytic function. Cl-amidine, a haloacetamidine-based molecule, and its more potent derivative BB-Cl-amidine, act by covalently modifying the active site cysteine residue of PADI3, thereby irreversibly inhibiting the enzyme's function. The inhibition mechanism involves the blockade of the enzyme's ability to convert arginine residues into citrulline on protein substrates, which is the hallmark activity of PADI3. Similarly, GSK199 is a small molecule that binds directly to the active site of PADI3, selectively inhibiting its activity by preventing the deimination process. Another covalent inhibitor, TDFA, targets PADI3 by forming a stable adduct with the catalytic cysteine, which is essential for the enzyme's action on arginine residues.

Moreover, Streptonigrin and Disulfiram disrupt PADI3's function by different mechanisms. Streptonigrin interacts with iron, generating reactive oxygen species that modify and inhibit the catalytic cysteine of PADI3. Disulfiram, known for its ability to chelate metal ions, can inhibit PADI3 by binding to its necessary calcium ions or by interacting with essential thiol groups within the enzyme, thus impairing its catalytic activity. Phenylarsine oxide and o-Phenanthroline also inhibit PADI3 by interacting with thiol groups or chelating metal ions, respectively, crucial for the enzyme's function. Brequinar, by inhibiting pyrimidine biosynthesis, leads to a reduction in nucleotide levels, which are known to regulate enzymatic activities, including that of PADI3. MLN4924 affects PADI3 indirectly by inhibiting NEDD8-activating enzyme, which may alter the neddylation status of cellular proteins, potentially changing PADI3's conformation or stability. NSC95397 inhibits Cdc25 phosphatases, which could lead to changes in cell cycle progression and indirectly affect PADI3's regulatory mechanisms or substrate availability. Lastly, Zinc pyrithione can bind to PADI3, potentially disrupting its structure or substrate interaction, resulting in the inhibition of its enzymatic activity.