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

N. V. Penkov, N. A. Penkova & V. I. Lobyshev

Abstract

The hydration of adenosine triphosphate (ATP), Mg · ATP, and Ca · 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 · ATP, which is not the case for ATP and Ca · ATP. The hydrodynamic diameter of Mg · ATP exceeds that of ATP and Ca · ATP, which is in agreement with the conclusion about the larger number of hydrogen bonds in the Mg · 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 · ATP complex.

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