Unno Masaki, Kizawa Kenji, Ishihara Makiko, Takahara Hidenari
Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Jun 1;68(Pt 6):668-70. doi: 10.1107/S1744309112015333. Epub 2012 May 23.
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.
在钙离子存在的情况下，人肽基精氨酸脱氨酶（PAD）可将蛋白质中的精氨酸残基转化为瓜氨酸。在已知的五种人PAD酶中，III型同工酶（PAD3）对合成底物和天然底物表现出最高的特异性。本研究旨在确定PAD3的结构，以阐明其选择性瓜氨酸化机制。使用聚乙二醇400作为沉淀剂获得的PAD3晶体，利用同步辐射衍射至2.95 Å分辨率。它们属于空间群R3，晶胞参数a = b = 114.97，c = 332.49 Å（六方轴）。假设一个不对称单位中包含两个分子，计算得到的马修斯系数为2.83 Å(3) Da(-1)，对应溶剂含量为56.6%。使用PAD4作为分子置换模型确定了初始相位。
