Special Role of Mg2+ in the Formation of the Hydration Shell of Adenosine Triphosphate

The hydration of adenosine triphosphate (ATP), Mg center dot ATP, and Ca center dot ATP in aqueous solutions has been analyzed based on the Terahertz Time-Domain Spectroscopy and Dynamic Light Scattering data. It is shown that the ATP binding with Mg2+ or Ca2+ leads to weakening of water binding in the hydration shell (apparently, due to the screening of the phosphate-group charge). It is also shown that an increased number of hydrogen bonds are formed in the hydration shells of Mg center dot ATP, which is not the case for ATP and Ca center dot ATP. The hydrodynamic diameter of Mg center dot ATP exceeds that of ATP and Ca center dot ATP, which is in agreement with the conclusion about the larger number of hydrogen bonds in the Mg center dot ATP hydration shell. The special role of Mg2+ in the ATP hydration may have a deep biological sense, because ATP is involved in most of biologically significant reactions specifically in the form of Mg center dot ATP complex.

Automated summary

Based on experimental analysis, it was found that the binding of ATP with Mg2+ or Ca2+ leads to weakened water binding in the hydration shell, while an increased number of hydrogen bonds are formed in the hydration shell of Mg·ATP. The hydrodynamic diameter of Mg·ATP is larger than that of ATP and Ca·ATP.