Shi Long, Xia Yong, Zhang Ming, Yin Shang-Jun, Si Yue-Xiu, Qian Guo-Ying, Lü Zhi-Rong, Zhou Hai-Meng, Park D, Chng G, Zou Fei, Park Yong-Doo
Department of Environmental Health, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou 510515, PR China.
Protein Pept Lett. 2011 Jul;18(7):726-32. doi: 10.2174/092986611795446021.
Superoxide dismutase (SOD, EC 1.15.1.1) plays an important antioxidant defense role in organisms exposed to oxygen. Copper- and zinc-containing SOD (Cu/Zn-SOD) catalysis and the change in folding behavior of this enzyme in response to inactivators are therefore of interest. We studied the inhibitory effects of trifluoroethanol (TFE) on the activity and conformation of a Cu/Zn-SOD from Bos taurus. We found that TFE inactivated the enzyme and disrupted the tertiary and secondary structures of Cu/Zn-SOD. Kinetic studies showed that TFE-induced inactivation of Cu/Zn-SOD follows first-order reaction kinetics and that TFE binding sites are distinct from the copper- and zinc-containing active site. These structural changes occurred prior to enzyme activity loss. A computational docking simulation of Cu/Zn-SOD and TFE (binding energy of Dock 6.3: -11.52 kcal/mol) suggested that THR37, ASP40, and GLU119, which are located near the active site, interact with TFE. Evaluation of the ligand binding kinetics of Cu/Zn-SOD during unfolding in the presence of TFE combined with computational prediction allowed us to gain insight into the inactivation of Cu/Zn-SOD.
超氧化物歧化酶（SOD，EC 1.15.1.1）在暴露于氧气的生物体中发挥着重要的抗氧化防御作用。因此，含铜和锌的超氧化物歧化酶（Cu/Zn-SOD）的催化作用以及该酶对失活剂响应时折叠行为的变化备受关注。我们研究了三氟乙醇（TFE）对来自牛的Cu/Zn-SOD的活性和构象的抑制作用。我们发现TFE使该酶失活，并破坏了Cu/Zn-SOD的三级和二级结构。动力学研究表明，TFE诱导的Cu/Zn-SOD失活遵循一级反应动力学，并且TFE结合位点与含铜和锌的活性位点不同。这些结构变化发生在酶活性丧失之前。对Cu/Zn-SOD和TFE进行的计算对接模拟（Dock 6.3的结合能：-11.52 kcal/mol）表明，位于活性位点附近的苏氨酸37、天冬氨酸40和谷氨酸119与TFE相互作用。在TFE存在下对Cu/Zn-SOD展开过程中的配体结合动力学进行评估，并结合计算预测，使我们能够深入了解Cu/Zn-SOD的失活情况。
