Swain A L, Jaskólski M, Housset D, Rao J K, Wlodawer A
Macromolecular Structure Laboratory, National Cancer Institute-Frederick Cancer Research and Development Center, MD 21702-1201.
Proc Natl Acad Sci U S A. 1993 Feb 15;90(4):1474-8. doi: 10.1073/pnas.90.4.1474.
The crystal structure of Escherichia coli asparaginase II (EC 3.5.1.1), a drug (Elspar) used for the treatment of acute lymphoblastic leukemia, has been determined at 2.3 A resolution by using data from a single heavy atom derivative in combination with molecular replacement. The atomic model was refined to an R factor of 0.143. This enzyme, active as a homotetramer with 222 symmetry, belongs to the class of alpha/beta proteins. Each subunit has two domains with unique topological features. On the basis of present structural evidence consistent with previous biochemical studies, we propose locations for the active sites between the N- and C-terminal domains belonging to different subunits and postulate a catalytic role for Thr-89.
大肠杆菌天冬酰胺酶II（EC 3.5.1.1）是一种用于治疗急性淋巴细胞白血病的药物（爱施巴），其晶体结构已通过使用来自单个重原子衍生物的数据并结合分子置换法在2.3埃分辨率下确定。原子模型被精修至R因子为0.143。这种酶作为具有222对称的同四聚体具有活性，属于α/β蛋白类别。每个亚基有两个具有独特拓扑特征的结构域。基于与先前生化研究一致的当前结构证据，我们提出了属于不同亚基的N端和C端结构域之间活性位点的位置，并假定苏氨酸-89具有催化作用。
