应用原子-键电负性均衡方法预测超氧化物歧化酶催化反应的活性部位

应用原子-键电负性均衡方法计算了超氧化物歧化酶的电荷分布和Fukui函数. 结果表明, 超氧化物歧化酶活性中心与超氧阴离子自由基作用时, 金属离子电荷转移在0.1 e～0.3 e之间, 而配体原子等的电荷转移却很小; 同时金属离子的Fukui函数大于配位原子的Fukui函数. 超氧化物歧化酶活性中心与抑制剂作用失活后, 金属离子的Fukui函数小于抑制剂中配位原子的Fukui函数. 电荷转移和Fukui函数表明, Mn, Fe和Cu离子分别是含锰、铁和铜锌超氧化物歧化酶的活性中心部位, 该预测不仅与量子化学理论计算一致, 而且与实验现象相吻合.

Prediction of Reactive Site in Superoxide Dismutase in Terms of Atom-Bond Electronegativity Equalization Method

The charge distribution and Fukui function in the superoxide dismutases were calculated in terms of an atom-bond electronegativity equalization method (ABEEM). The results show that charge transfers of metal ions range from 0.1e to 0.3e, and charge transfers of the coordinated atoms and others are quite small when the active center in the superoxide dismutase catalyzes the superoxide anion radical. Fukui function of a metal ion is bigger than those of the coordinated atoms and others at the active center, but smaller than those of the atoms in the inactive form combined with the inhibitors. The prediction that Mn, Fe and Cu ions are the active center sites in manganese-containing superoxide dismutase, iron-containing superoxide dis- mutase and copper- and zinc-containing superoxide dismutase, respectively, agrees with both the quantum chemical theoretical computation and the experiments.