Kuroki Ryota, Hirose Masako, Kato Yoichi, Feese Michael D, Tamada Taro, Shigematsu Hideki, Watarai Hiroshi, Maeda Yoshitake, Tahara Tomoyuki, Kato Takashi, Miyazaki Hiroshi
Central Laboratories for Key Technology, Kirin Brewery Co. Ltd, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.
Acta Crystallogr D Biol Crystallogr. 2002 May;58(Pt 5):856-8. doi: 10.1107/s0907444902004791. Epub 2002 Apr 26.
Thrombopoietin (TPO) is a cytokine which primarily stimulates megakaryocytopoiesis and thrombopoiesis. The functional domain of TPO (TPO(163)) consisting of the N-terminal 163 amino acids was prepared and crystallized. Since the crystallization of TPO(163) was unsuccessful using the standard screening methods, a Fab fragment derived from a neutralizing monoclonal antibody was used for crystallization. It was found that the TPO(163)-Fab complex crystallized reproducibly in 0.1 M potassium phosphate buffer pH 6.0 containing 20-25% polyethylene glycol 4000. Thin crystals (0.2 x 0.2 x 0.02 mm) grew in two space groups: P2(1), with unit-cell parameters a = 133.20, b = 46.71, c = 191.47 A, beta = 90.24 degrees, and C2, with unit-cell parameters a = 131.71, b = 46.48, c = 184.63 A, beta = 90.42 degrees. The results of a molecular-replacement analysis indicate that the Fab molecules interact with each other and provide a suitable interface for crystallization.
血小板生成素（TPO）是一种主要刺激巨核细胞生成和血小板生成的细胞因子。制备并结晶了由N端163个氨基酸组成的TPO功能结构域（TPO(163)）。由于使用标准筛选方法未能成功使TPO(163)结晶，因此使用源自中和性单克隆抗体的Fab片段进行结晶。结果发现，TPO(163)-Fab复合物在含有20-25%聚乙二醇4000的pH 6.0的0.1 M磷酸钾缓冲液中可重复结晶。薄晶体（0.2×0.2×0.02 mm）在两个空间群中生长：P2(1)，晶胞参数为a = 133.20，b = 46.71，c = 191.47 Å，β = 90.24°；以及C2，晶胞参数为a = 131.71，b = 46.48，c = 184.63 Å，β = 90.42°。分子置换分析结果表明，Fab分子相互作用并为结晶提供了合适的界面。
