Cl-Amidine (Hydrochloride), 5 mg

Protein arginine deiminase (PAD) activity, which converts peptidyl-arginine to peptidyl-citrulline in histones and other substrates, can be suppressed in cell-based and biochemical assays with Cl-Amidine hydrochloride, a cell-permeable haloacetamidine-based irreversible inhibitor from STEMCELL Technologies. The compound covalently engages the active-site cysteine of PAD2, PAD4, and related isozymes, blocking citrullination in a dose-dependent manner and serving as a chemical complement to genetic knockout and CRISPR-based approaches.

In the research laboratory, this PAD inhibitor is routinely applied to dissecting neutrophil extracellular trap (NET) formation, chromatin decondensation, and innate immune signaling pathways. Published studies use Cl-Amidine in in vitro models of rheumatoid arthritis, multiple sclerosis, lupus, sepsis, and certain cancers where aberrant citrullination contributes to disease pathology. It is also employed as a tool compound to validate PAD-dependent hits in citrullinomic profiling and histone modification studies.

The hydrochloride salt improves aqueous solubility over the free base, allowing stock solutions to be prepared in DMSO or sterile water for direct addition to cell culture media. Working concentrations typically range from 1 to 200 uM, with exposure times of 1 to 24 hours depending on cell type and assay endpoint. Each 5 mg vial provides ample material for dozens of small-scale experiments. Store the unopened vial at -20 degrees C, protected from light and moisture, and allow it to equilibrate to room temperature before opening; reconstituted stocks should be aliquoted and frozen to limit freeze-thaw degradation of the active compound. For research use only.