Activity Based Protein Profiling Reagents for Protein Arginine Deiminase 4 (PAD4): Synthesis and in vitro Evaluation of a Fluorescently-labeled Probe

摘要

Protein Arginine Deiminase 4 (PAD4), which catalyzes the post-translational conversion of peptidyl-arginine to peptidyl-citrulline, is widely regarded as one of the best new targets for the development of a novel Rheumatoid Arthritis therapeutic. In addition to its presumed role in this disease, PAD4 is also a calcium dependent histone deiminase that acts as a transcriptional corepressor. Herein we describe the design, synthesis and in vitro evaluation of two fluorescently labeled activity based protein profiling (ABPP) reagents that specifically and irreversibly modify the active, i.e. calcium bound, form PAD4 with equal affinity to previously described small molecule chemical probes of PAD4 function. These fluorescently tagged ABPPs will be useful for identifying the conditions under which this enzyme is activated in vivo and may prove to be useful RA diagnostics.