本文采用量子力学/分子力学相结合方法（QM/MM）对一新近合成的超氧化物歧化酶（SOD）模拟物{[Cu(L)(H2O)(βCD)]2(im)}3+的催化活性进行理论研究。当人体内的超氧阴离子自由基（O2•-）过剩时，则它可损害细胞并引起多种疾病。SOD的生物作用是可清除体内的超氧阴离子自由基。其主要的催化作用是将O2•-离子通过歧化反应而变为O2和H2O2分子。本文主要研究的是该歧化反应的第一个半反应，即SOD+O2•-+H+→SODH+O2。通过理论计算优化了反应过程所涉及的化合物的几何构型，并采用NBO方法对其化合物的电子结构进行了分析，由此探讨该SOD模拟物的催化活性。计算结果表明：该SOD模拟物吸附.OOH后，体系更稳定，其结合能为9 kcal/mol。在反应过程中，.OOH中的H以质子的形态向咪唑环中的N原子迁移，且Cu离子被还原，O2•-被氧化。而处于两个五元环交点的N，由于其所受张力较大，与其它配位N原子比较，其Cu-N键长较大，N原子所带负电荷及二级稳定化能均较小，使其的配位能力下降。而连接两个金属铜的咪唑环内的电子具有共轭性，对稳定整个体系的构型起到了一定的作用。优化得到了反应过程的过渡态，计算的正反应的活化位垒为5.1kcal/mol，表明了反应进行的可行性。

The catalytic activity of {[Cu(L)(H2O)(βCD)]2(im)}3+ , i. e. the mimic of superoxide dismutase (SOD), which was recently synthesized, have been theoretically studied by using the combination method of quantum mechanics and molecular mechanics (QM/MM). The extraction toxic superoxide radial（O2•-）in a body may damage the live cell and cause many diseases for human. SOD activity can decrease the amount of O2•- ions through the dismutation reaction of toxic superoxide radial to oxygen and hydrogen peroxide molecules. The first half reaction of such dismutation reaction, namely SOD+O2•-+H+→SODH+O2, has been investigated here. We have optimized the geometries of complexes involved in this reaction and analyzed their electronic structures by using NBO method and the catalytic activity. The present results show that such mimic can stably adsorbed .OOH radio with the binding energy of 9 kcal/mol. The first half-reaction involves a hydrogen transferring from OOH to the N atom of imidazole, resulting in the reduction of Cu(Ⅱ) and oxidation of O2•-. The N atom located at the cross-sit of two five-member rings in the mimic has a longer Cu-N distance, the smaller negative charge and second stability energy, consequently has a weaker coordination ability with Cu atom, compared with those for the other coordination N atoms. The electrons in the imidazole bridging two Cu atoms have the conjugation properties, resulting in stabilizing such SOD structures. The structure of transition state has been optimized and the calculated activation barrier is about5.1kcal/mol, which shows the available process of first half reaction.