Much research has been done so far for the physical understanding of ATP energy. Until the 1960s, ATP energy was considered to be inherent in the molecular structure of ATP ions themselves, and we tried to explain its high energy by quantum mechanics calculation, but we could not quantitatively explain the experimental values. In the 1990s, quantum mechanics calculations were made that incorporated the effects of water as a continuum.However, it was difficult to evaluate the free hydration energy of each of the solutes (reactant ion and product ion) dissolved in water due to the enormous amount of calculation.

　This time, the research group has independently developed a system that calculates by connecting a large number of CPUs (computer central processing units) in parallel. It enables high-speed quantum mechanics simulation for ATP and ADP.Furthermore, we have succeeded in calculating the energy of ATP hydrolysis reaction in water with high accuracy by fusing the high-precision and high-speed hydration free energy calculation method developed by Professor Nobuyuki Matsubayashi (Graduate School of Engineering) of Osaka University.

　Calculations show that the large decrease in electron energy and the large increase in solute free hydration energy associated with the dissociation of ATP are subtly canceled in the medium of water.As a result, the microscopic mechanism by which the free hydrolysis energy becomes almost constant regardless of the ionic valence of ATP was clarified for the first time.This achievement rewrites many descriptions in biology textbooks about ATP energy release.

Paper Information: [Journal of Physical Chemistry B] Drastic Compensation of Electronic and Solvation Effects on ATP Hydrolysis Revealed through Large-Scale QM / MM Simulations Combined with a Theory of Solutions