Cayman's PAD1 Inhibitor Screening Assay Kit (AMC) provides a convenient method for screening human PAD1 inhibitors. This assay utilizes a fluorescent substrate (Z-Arg-AMC) consisting of an arginine residue, a carboxybenzyl group, and a fluorophore (7-amino-4-methylcoumarin, AMC). Acylation of AMC onto the arginine residue masks the fluorescence of the fluorophore. In the absence of PAD1, the substrate remains unaltered, allowing the developer to release free AMC. In the presence of PAD1, the arginine of the substrate is citrullinated, and while the reaction is quenched by the addition of developer, free AMC is not released. Fluorescence is analyzed with an excitation wavelength of 355-365 nm and an emission wavelength of 445-455 nm. The fluorescent signal is inversely proportional to the amount of citrullination by PAD1.