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首页> 外文期刊>Chemical research in toxicology >The Structure of DNA Dictates Purine Atom Site Selectivity in Alkylation by Primary Diazonium Ions
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The Structure of DNA Dictates Purine Atom Site Selectivity in Alkylation by Primary Diazonium Ions

机译：DNA的结构通过伯重氮离子烷基化的嘌呤原子位点选择性。

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The 1-propanediazonium ion,generated from N'-nitro-N-nitroso-N-propylguanidine in aqueous solutions,was reacted with the purine nucleosides dGuo and dAdo or single-stranded or double-stranded DNA.After nucleobase liberation by acid hydrolysis,the percent yields of products were determined by LC/MS using either isotopically distinct internal standards in the case of the nucleoside reactions or an internal standard and the ratios of response factors of all other products that were separately determined in the case of the reactions with DNA.In the reactions of nucleosides,products of both n-propylation and iso-propylation at all of the heroatoms were observed.For these reactions,the yields of the three most abundant n-propyl adducts of Gua are in the order O~6 > N7 > N~2,in the ratio of 9.0/6.4/1,while for Ade,the order of the yields of N-propyl products is Nl > N7 > N3 > N~6 in the ratio 2.5/1.8/1.1/1.The ratios of n-propylated to iso-propylated products at each site,PJPi,generally a measure of enhancement of SN_2 displacement on the diazonium ion,vary with each heteroatom but by no more than a factor of 6 for Gua and a factor of 3 for Ade.In the reactions with duplex DNA,products of reactions at all sites could not be detected.In addition,much larger selectivities are observed,similar to what has been observed by others in the reactions with ethanediazo-nium ion.Thus,P_nIPi=30,21,and 0.9 for N7,O~6,and N~2 of Gua.Similarly,the values of PJPi are 11 and 8 for N3 and N7 of Ade.Reactions with single-stranded DNA give values of PJPi that are intermediate between the nucleoside reactions and the reactions of duplex DNA in most cases.The factors responsible for the relatively small atom site selectivities intrinsic to the nucleosides are analyzed,and reasons for enhanced S_N2 nucleophilicity in duplex DNA are discussed.
机译：在水溶液中由N'-硝基-N-亚硝基-N-丙基胍生成的1-丙二重氮离子与嘌呤核苷dGuo和dAdo或单链或双链DNA反应。在核苷反应的情况下，使用同位素不同的内标，或者通过内标，通过LC / MS确定产品的收率百分比;在与DNA的反应情况下，分别确定所有其他产品的响应因子之比在核苷的反应中，观察到所有英雄原子上的正丙基化和异丙基化产物。对于这些反应，Gua的三种最丰富的正丙基加合物的产率为O〜6> N7> N〜2，比率为9.0 / 6.4 / 1，而对于Ade，N-丙基产物的收率顺序为Nl> N7> N3> N〜6，比率为2.5 / 1.8 / 1.1 / 1每个位置的正丙基化产物与异丙基化产物之比PJPi通常为可以确保重氮离子上SN_2位移的增强，每个杂原子的变化不大，但Gua的不超过6倍，Ade的不超过3倍。在与双链DNA的反应中，所有位点的反应产物此外，观察到更大的选择性，类似于其他人在与乙二唑鎓离子反应中观察到的选择性。因此，P_nIPi = 30,21，N7，O〜6和N〜2的P为0.9。同样，Ade的N3和N7的PJPi值为11和8.与单链DNA的反应给出的PJPi值在大多数情况下介于核苷反应和双链DNA反应之间。分析了核苷固有的相对较小的原子位点选择性，并讨论了双链DNA中S_N2亲核性增强的原因。

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