Hydrogen bonds of RNA are stronger than those of DNA, but NMR monitors only presence of methyl substituent in uracil/thymine
Hydrogen bonds of RNA are stronger than those of DNA, but NMR monitors only presence of methyl substituent in uracil/thymine
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DOI：
10.1021/ja045276b
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发表时间：
2004-12-29
影响因子：
15
通讯作者：
Bickelhaupt, FM
中科院分区：
文献类型：
--
作者：
Swart, M;Guerra, CF;Bickelhaupt, FM
最近，Vakonakis和Liwang(J.Am化学。Soc.2004,126,5688)报道了RNA A：U比DNA A：T碱基对中更强的氢键的实验证据，这是基于腺嘌呤C2的核磁共振屏蔽的差异。我们用密度泛函理论分析了核磁共振屏蔽与氢键强度之间的关联。虽然我们同意A：U更强结合的结论，但我们发现C2的氢键强度与核磁共振屏蔽之间没有相关性。我们的研究表明，核磁共振只探测胸腺嘧啶/尿嘧啶中甲基的存在或不存在，与所涉及的氢键的强度没有任何关系。换句话说，我们不能从腺嘌呤C2的−屏蔽常数来推断沃森核磁共振克里克氢键的强度。
Recently, Vakonakis and LiWang (J. Am. Chem. Soc.2004,126, 5688) reported experimental evidence for stronger hydrogen bonds in RNA A:U than in DNA A:T base pairs, which was based on differences in NMR shielding for adenine C2. We have analyzed the proposed correlation between NMR shielding and hydrogen-bond strength using density functional theory. Although we agree with the conclusion that A:U is more strongly bound, we find no correlation between the hydrogen-bond strength and the NMR shielding of C2. Our study shows that NMR merely probes the presence/absence of the methyl group in thymine/uracil, without any relation to the strength of the hydrogen bonds involved. In other words, one cannot infer the Watson−Crick hydrogen-bond strength from the NMR shielding constant of adenine C2.