Question

By ATP hydrolysis, I mean the chemical reaction: ATP + Water -> ADP + Pi. Focusing only on the reaction, this is a nucleophillic substitution reaction, most likely occuring in SN2 mechanism. But so far, I haven't found a single paper reporting the energy of activation of this reaction uncatalyzed. So, does anyone actually measured/estimated the activation energy of uncatalyzed ATP hydrolysis reaction?

Answer 1

The activation energy for uncatalyzed ATP hydrolysis is not well-documented in the literature. However, the reaction is known to be highly exergonic with a standard free energy change. Within cells, ATP functions as an energy currency and its hydrolysis is used to drive various endergonic processes through energy coupling.

Step-by-step explanation:

The activation energy of uncatalyzed ATP hydrolysis has indeed not been a focus of many studies, which is why specific data on this subject might be hard to find in literature. The hydrolysis of ATP to ADP and inorganic phosphate (Pi) is a nucleophilic substitution reaction that releases a significant amount of free energy. This energy is pivotal for driving a myriad of cellular processes.

ATP hydrolysis is a spontaneous reaction and is considered highly exergonic, with a standard free energy change (ΔG°') of about -7.3 kcal/mol (-30.5 kJ/mol) which doubles under cellular conditions, reaching approximately -14 kcal/mol (-57 kJ/mol). In the cell, ATP acts as an energy currency, and its hydrolysis is coupled with energy-requiring reactions, a concept known as energy coupling.