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1、物理化学学报(WuliHuaxueXuebao)JulyActaPhys.鄄Chim.Sin.,2008,24(7)：1207-12131207[Article]www.whxb.pku.edu.cn过氧亚硝酸与酪氨酸的反应机理鄢王云海刘永东罗云敬钟儒刚(北京工业大学生命科学与生物工程学院,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鄄311G(d,p)水平上对该反应体系的反应物、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
2、,而是先分解产生自由基(·OH和·NO2),而后再与酪氨酸分步作用.过氧亚硝酸与酪氨酸的反应生成两种主要产物,分别为3鄄羟基酪氨酸和3鄄硝基酪氨酸,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：O641MechanismsoftheReactionofPeroxynitrousAcidandTyrosine鄢WANGYun鄄HaiLIUYong
3、鄄DongLUOYun鄄JingZHONGRu鄄Gang(CollegeofLifeScienceandBioengineering,BeijingUniversityofTechnology,Beijing100022,P.R.China)Abstract：Themechanismsofthereactionofperoxynitrousacidandtyrosinewerestudiedusingthedensityfunctionaltheory(DFT)atB3LYP/6鄄311G(d,p)level.Thegeometriesof
4、allthemoleculeswereoptimized;theharmonicvibrationfrequenciesandtheenergieswerecalculatedaswell.Thecalculationresultsshowedthatstepwisemechanismratherthanconcertedmechanismwaspreferredforthereactionofperoxynitrousacidandtyrosine.ThestepwisepathwaystartedwithhomolysisoftheHO
5、—ONObondtodiscrete·OHand·NO2radicals,whichthenreactedwithtyrosineviatwodifferentpathways:(i)theHatomoftyrosinehydroxylwasabstractedby·OHtoproduceIM3,whichthencombinedwith·NO2formingtheintermediate(IM1).Subsequently,theIM1underwentfurthertransformationleadingtotheproductof3
6、鄄nitrotyrosine.(ii)the·OHwasaddedtothephenolringoftyrosinetoproducetheIM2,whichthencombinedwith·NO2formingtheintermediate(IM21).TheIM21alsounderwentfurthertransformationleadingtotheproductof3鄄hydroxytyrosine.Theactivationenergiesoftherate鄄determiningstepsofthesetwopathways
7、were82.86and48.05kJ·mol-1,respectively.Thisconclusionwasingoodagreementwiththecorrespondingexperimentaldata.Additionally,effectsofaqueoussolvationofwateronthisreactionwerealsoinvestigatedandtheresultsindicatedthatthereactionpreferablytookplaceinwater.KeyWords：Peroxynitrous
8、acid;Radical;Tyrosine;Densityfunctionaltheory-过氧亚硝酸根(ONOO)是一种能够在生物体细氨酸残基的修饰可以改变其生物活性,从而影响
