5′ carbon atom of the sugar to a food that starts with z group. Being polyanionic and featuring a potentially chelating polyphosphate group, ATP binds metal cations with high affinity.

The binding of a divalent cation, almost always magnesium, strongly affects the interaction of ATP with various proteins. A second magnesium ion is critical for ATP binding in the kinase domain. Salts of ATP can be isolated as colorless solids. 2 and 1 represent input and output of energy, respectively. ATP is stable in aqueous solutions between pH 6. 4, in the absence of catalysts. Living cells maintain the ratio of ATP to ADP at a point ten orders of magnitude from equilibrium, with ATP concentrations fivefold higher than the concentration of ADP.