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Updated: May 21, 2026
Production, Crystallization and Structure Determination of C. difficile PPEP-1 via Microseeding and Zinc-SAD
Published on: December 30, 2016
Crystallization and preliminary X-ray crystallographic analysis of human peptidylarginine deiminase type III
Masaki Unno1, Kenji Kizawa, Makiko Ishihara
1Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan. unno19@mx.ibaraki.ac.jp
Abstract:
In the presence of calcium ions, human peptidylarginine deiminase (PAD) converts arginine residues in proteins to citrulline. Of the five known human PAD enzymes, the type III isozyme (PAD3) exhibits the highest specificity for synthetic and natural substrates. This study aimed to determine the structure of PAD3 in order to elucidate its selective citrullination mechanism. Crystals of PAD3 obtained using polyethylene glycol 400 as a precipitant diffracted to 2.95 Å resolution using synchrotron radiation. They belonged to space group R3, with unit-cell parameters a = b = 114.97, c = 332.49 Å (hexagonal axes). Assuming two molecules were contained in an asymmetric unit, the calculated Matthews coefficient was 2.83 Å(3) Da(-1), corresponding to a solvent content of 56.6%. Initial phases were determined using PAD4 as a molecular-replacement model.
