<P> Hydrolysis of the phosphate groups in ATP is especially exergonic, because the resulting orthophosphate group is greatly stabilized by multiple resonance structures, making the products (ADP and P) much lower in energy than the reactant (ATP). The high negative charge density associated with the three adjacent phosphate units of ATP also destabilizes the molecule, making it higher in energy . Hydrolysis relieves some of these electrostatic repulsions, liberating useful energy in the process by causing conformational changes in enzyme structure . </P> <P> In humans, approximately 60 percent of the energy released from the hydrolysis of one mole of ATP produces metabolic heat rather than fuel the actual reactions taking place . Due to the acid - base properties of ATP, ADP, and inorganic phosphate, the hydrolysis of ATP has the effect of lowering the pH of the reaction medium . Under certain conditions, high levels of ATP hydrolysis can contribute to lactic acidosis . </P> <P> Hydrolysis of the terminal phosphoanhydridic bond is a highly exergonic process . The amount of released energy depends on the conditions in a particular cell . Specifically, the energy released is dependent on concentrations of ATP, ADP and P. As the concentrations of these molecules deviate from values at equilibrium, the value of Gibbs free energy change (ΔG) will be increasingly different . In standard conditions (ATP, ADP and P concentrations are equal to 1M, water concentration is equal to 55M) the value of ΔG is between - 28 to - 34 kJ / mol . </P> <P> The range of the ΔG value exists because this reaction is dependent on the concentration of Mg cations, which stabilize the ATP molecule . The cellular environment also contributes to differences in the ΔG value since ATP hydrolysis is dependent not only on the studied cell, but also on the surrounding tissue and even the compartment within the cell . Variability in the ΔG values is therefore to be expected . </P>

What is the delta g for atp hydrolysis