过氧亚硝酸与酪氨酸的反应机理.pdfVIP

理化学学报(Wuli Huaxue Xuebao) July A cta Phys. Chim. Sin., 2008, 24(7) ：1207-1213 1207 [Article] 过氧亚硝酸与酪氨酸的反应机理 云海 刘永东 罗云敬 钟儒刚 (北京工业大学生命科学与生 工程学院, 北京 100022) 摘要： 用密度泛函理论(DFT)研究了过氧亚硝酸与酪氨酸的反应机理. 在B3LYP/6 311G(d,p )水平上对该反应 体系的反应 、中间体、过渡态和产物进行了几何构型优化并计算了振动频率和能量. 计算结果表明, 过氧亚硝 酸不易直接与酪氨酸反应, 而是先分解产生自由基( ·OH 和·NO ), 而后再与酪氨酸分步作用. 过氧亚硝酸与酪氨 2 酸的反应生成两种主要产 , 分别为3 羟基酪氨酸和3 硝基酪氨酸, 这一结论与实验所得到的结果一致. 此外在 同一计算水平上采用SCRF(PCM)方法计算了溶剂化效应, 结果表明, 极性溶剂可以增加自由基结合的稳定化能, 并降低反应通道的活化能, 有利于反应的进行. 关键词： 过氧亚硝酸; 自由基; 酪氨酸; 密度泛函理论 中图分类号： O641 Mechanisms of the Reaction of Peroxynitrous Acid and Tyrosine WANG Yun Hai LIU Yong Dong LUO Yun Jing ZHONG Ru Gang (College of Lif e Science and Bioengineering, Beij ing University of Technology, Beijing 100022, P. R. China) Abstract ： The mechanisms of the reaction of peroxynitrous acid and tyrosine were studied using the density functional theory (DFT) at B3LYP/6 311G(d,p) level. The geometries of all the molecules were optimized; the harmonic vibration frequencies and the energies were calculated as well. The calculation results showed that stepwise mechanism rather than concerted mechanism was preferred for the reaction of peroxynitrous acid and tyrosine. The stepwise pathway started with homolysis of the HO—ONO bond to discrete ·OH and ·NO2 radicals, which then reacted with tyrosine v ia two different pathways: (i) the H atom of tyrosin