Hydrolysis of adenosine. A semiempirical and ab initio study
Hydrolysis of adenosine. A semiempirical and ab initio study
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DOI：
10.1016/0166-1280(95)04440-x
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发表时间：
1996-04-15
影响因子：
--
通讯作者：
Lonnberg, H
中科院分区：
文献类型：
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作者：
Hotokka, M;Lonnberg, H
用半经验和从头算方法计算了腺苷、3-甲基腺苷和一系列相关模型化合物N-糖苷键的电子分布、质子亲和能和异解裂解能。在气相中，腺苷质子化的首选位置是腺嘌呤环上的氮N3，N1位几乎是碱性的。在溶液中，溶剂效应改变了顺序，使N7成为质子化的首选位置。3-甲基腺苷离子很可能在N7被质子化。质子化作用(或N3甲基化作用)对骨架原子的净原子电荷，特别是N-糖苷键的净原子电荷影响不大。然而，该键的电子密度降低，从而削弱了键。通过N7质子化或N3甲基化得到的单阳离子的影响最为显著。根据这些结果讨论了以前报道的反应速率的变化。
The electron distributions, proton affinities and energies of the heterolytic fission of the N-glycosidic bond of adenosine, 3-methyladenosine and a set of related model compounds have been calculated by semiempirical and ab initio methods. In the gas phase the preferred site of protonation in adenosine is nitrogen N3 of the adenine ring, the N1 site being almost as basic. In solution solvent effects change the order, making N7 the preferred protonation site. The 3-methyladenosinium ion is most likely protonated at N7. The net atomic charges of the skeleton atoms, in particular in the N-glycosidic bond, are not markedly affected by protonation (or by N3 methylation). Yet the electron density of this bond is decreased and the bond is hence weakened. The influence is most prominent with the monocations obtained by N7 protonation or N3 methylation. The previously reported variations of reaction rates are discussed on the basis of these results.