Statistical mechanical integral equation approach to reveal the solvation effect on hydrolysis free energy of ATP and its analogue

Investigations of the hydrolysis reactions of adenosine triphosphate (ATP) and pyrophosphate in solution by the three-dimensional reference interaction site model self-consistent field (3D-RISM-SCF) theory are briefly reviewed. The theory is applied to the four different charged states of pyrophosphate, for which experimental data of hydrolysis free energies are available. The results of the reaction free energy for all the four charged states are almost constant, -8 kcal/mol, in accord with the experimental results, but in marked contrast to the conventional view, or the high-energy P-O bond hypothesis. The theory is also applied to the hydrolysis reaction of ATP to clarify the molecular origin of the energy produced by the ATP hydrolysis.