Tautomeric Equilibrium, Stability, and Hydrogen Bonding in 2'-Deoxyguanosine Monophosphate Complexed with Mg2+

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• 作者：Dmytro Kosenkov ; Leonid Gorb ; Oleg V. Shishkin ; Jir&iacute ; poner ; Jerzy Leszczynski
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：January 10, 2008
• 年：2008
• 卷：112
• 期：1
• 页码：150 - 157
• 全文大小：257K
• 年卷期：v.112,no.1(January 10, 2008)
• ISSN：1520-5207

文摘

The tautomeric equilibrium and hydrogen bonding in nucleotide 2'-deoxyguanosine monophosphate thatinteracts with hydrated Mg²⁺ cation (4H₂O·Mg[dGMP]) were studied at the MP2/cc-pVDZ//B3LYP/cc-pVDZand B3LYP/aug-cc-pVTZ//B3LYP/cc-pVDZ levels of theory. The Mg²⁺ ion forms two inner-shell contactswith the nucleotide, similar to small phosphorylated molecules under physiological conditions. The presenceof the phosphate group and the hydrated magnesium cation leads to a change in guanine tautomeric equilibriumof 4H₂O·Mg[dGMP] in comparison to free guanine. The influence of the phosphate group and the magnesiumcation on tautomeric equilibrium is larger in the anti conformation where the P=OMg and MgN7 coordinatebonds are formed. The canonical oxo form of guanine is more stable (by 6-8 kcal/mol) than the O6-hydroxoform in anti conformation. Thus, the interaction with Mg²⁺ ion is capable of further suppressing the likelihoodof a spontaneous transient formation of the rare tautomer. In the syn conformation of 4H₂O·Mg[dGMP], theinteraction of the guanine nucleobase with the phosphate group and the magnesium cation is not as strong asin the anti conformation, and the relative stability of guanine tautomers is close to those in free guanine.