Elucidating the Molecular Origin of Hydrolysis Energy of Pyrophosphate in Water
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- 作者：Jooyeon Hong ; Norio Yoshida ; Song-Ho Chong ; Chewook Lee ; Sihyun Ham ; Fumio Hirata
- 刊名：Journal of Chemical Theory and Computation
- 出版年：2012
- 出版时间：July 10, 2012
- 年：2012
- 卷：8
- 期：7
- 页码：2239-2246
- 全文大小：400K
- 年卷期：v.8,no.7(July 10, 2012)
- ISSN：1549-9626
文摘
The molecular origin of the energy produced by the ATP hydrolysis has been one of the long-standing fundamental issues. A classical view is that the negative hydrolysis free energy of ATP originates from intramolecular effects connected with the backbone P鈥揙 bond, so called 鈥渉igh-energy bond鈥? On the other hand, it has also been recognized that solvation effects are essential in determining the hydrolysis free energy. Here, using the 3D-RISM-SCF (three-dimensional reference interaction site model self-consistent field) theory that integrates the ab initio quantum chemistry method and the statistical mechanical theory of liquids, we investigate the molecular origin of hydrolysis free energy of pyrophosphate, an ATP analogue, in water. We demonstrate that our theory quantitatively reproduces the experimental results without the use of empirical parameters. We clarify the crucial role of water in converting the hydrolysis free energy in the gas phase determined solely by intramolecular effects, which ranges from endothermic, thermoneutral, to highly exothermic depending on the charged state of pyrophosphate, into moderately exothermic in the aqueous phase irrespective of the charged state as observed in experimental data. We elucidate that this is brought about by different natures of solute鈥搘ater interactions depending on the charged state of solute species: the hydration free energy of low-charged state is mainly subjected to short-range hydrogen-bonds, while that of high-charged state is dominated by long-range electrostatic interactions. We thus provide unambiguous evidence on the critical role of water in determining the ATP hydrolysis free energy.