Gomez German A, Morisseau Christophe, Hammock Bruce D, Christianson David W
Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
Biochemistry. 2004 Apr 27;43(16):4716-23. doi: 10.1021/bi036189j.
The X-ray crystal structure of human soluble epoxide hydrolase (sEH) has been determined at 2.6 A resolution, revealing a domain-swapped quaternary structure identical to that observed for the murine enzyme [Argiriadi, M. A., Morisseau, C., Hammock, B. D., and Christianson, D. W. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 10637-10642]. As with the murine enzyme, the epoxide hydrolytic mechanism of the human enzyme proceeds through an alkyl-enzyme intermediate with Asp-333 in the C-terminal domain. The structure of the human sEH complex with N-cyclohexyl-N'-(iodophenyl)urea (CIU) has been determined at 2.35 A resolution. Tyr-381 and Tyr-465 donate hydrogen bonds to the alkylurea carbonyl group of CIU, consistent with the proposed roles of these residues as proton donors in the first step of catalysis. The N-terminal domain of mammalian sEH contains a 15 A deep cleft, but its biological function is unclear. Recent experiments demonstrate that the N-terminal domain of human sEH catalyzes the metal-dependent hydrolysis of phosphate esters [Cronin, A., Mowbray, S., Dürk, H., Homburg, S., Fleming, I., Fisslthaler, B., Oesch, F., and Arand, M. (2003) Proc. Natl. Acad. Sci. U.S.A. 100, 1552-1557; Newman, J. W., Morisseau, C., Harris, T. R., and Hammock, B. D. (2003) Proc. Natl. Acad. Sci. U.S.A. 100, 1558-1563]. The binding of Mg(2+)-HPO4(2-) to the N-terminal domain of human sEH in its CIU complex reveals structural features relevant to those of the enzyme-substrate complex in the phosphatase reaction.
人可溶性环氧化物水解酶（sEH）的X射线晶体结构已在2.6埃分辨率下测定，揭示了一种结构域交换的四级结构，与鼠源酶中观察到的结构相同[阿吉里亚迪，M. A.，莫里索，C.，汉莫克，B. D.，和克里斯蒂安森，D. W.（1999年）《美国国家科学院院刊》96，10637 - 10642]。与鼠源酶一样，人源酶的环氧化物水解机制通过C末端结构域中含天冬氨酸-333的烷基酶中间体进行。人sEH与N - 环己基 - N' - （碘苯基）脲（CIU）复合物的结构已在2.35埃分辨率下测定。酪氨酸-381和酪氨酸-465向CIU的烷基脲羰基提供氢键，这与这些残基在催化第一步中作为质子供体的推测作用一致。哺乳动物sEH的N末端结构域包含一个15埃深的裂隙，但其生物学功能尚不清楚。最近的实验表明，人sEH的N末端结构域催化磷酸酯的金属依赖性水解[克罗宁，A.，莫布雷，S.，迪尔克，H.，洪堡，S.，弗莱明，I.，菲斯拉特勒，B.，厄施，F.，和阿兰，M.（2003年）《美国国家科学院院刊》100，1552 - 1557；纽曼，J. W.，莫里索，C.，哈里斯，T. R.，和汉莫克，B. D.（2003年）《美国国家科学院院刊》100，1558 - 1563]。Mg(2 + ) - HPO4(2 - )与人sEH在其CIU复合物中的N末端结构域的结合揭示了与磷酸酶反应中酶 - 底物复合物相关的结构特征。
