1802637-39-3

BB-Cl-Amidine is a modified version of Cl-amidine that retains the functional components but possesses a C-terminal benzimidazole group designed to limit proteolysis of the C-terminal amide. BB-Cl-Amidine irreversibly inactivates all four PAD subtypes (k_inact/K_I = 16,100, 4,100, 6,800, and 13,300 M^-1min^-1 for PAD1-4, respectively) by covalently modifying an active site cysteine that is important for its catalytic activity. The cellular potency of BB-Cl-amidine against PAD4 is increased 20-fold over the parent compound (EC₅₀ = 8.8 μM versus >200 μM for Cl-amidine). BB-Cl-Amidine also has a significantly longer in vivo half-life than Cl-amidine (1.75 h versus ~15 min, respectively). Both compounds inhibit the formation of neutrophil extracellular traps without altering H₂O₂ production by neutrophils. BB-Cl-Amidine is effective in vivo, improving endothelial function while downregulating the expression of type I interferon-regulated genes in MRL/lpr mice.