Autocitrullination and Changes in the Activity of Peptidylarginine Deiminase 3 Induced by High Ca Concentrations.

Peptidylarginine deiminases (PADs) are enzymes that catalyze the Ca-dependent conversion of arginine residues into proteins to citrulline residues. Five PAD isozymes have been identified in mammals. Several studies have shown that the active-site pockets of these isozymes are formed when Ca ions are properly bound.

Structures of human peptidylarginine deiminase type III provide insights into substrate recognition and inhibitor design.

Peptidylarginine deiminase type III (PAD3) is an isozyme belonging to the PAD enzyme family that converts arginine to citrulline residue(s) within proteins. PAD3 is expressed in most differentiated keratinocytes of the epidermis and hair follicles, while S100A3, trichohyalin, and filaggrin are its principal substrates. In this study, the X-ray crystal structures of PAD3 in six states, including its complex with the PAD inhibitor Cl-amidine, were determined.