Ester hydrolyses, driving force

Once the phosphate ester is hydrolysed, there is an immediate rapid tautomerism to the keto form, which becomes the driving force for the metabolic transformation of phosphoenolpyruvic acid into pyruvic acid, and explains the large negative free energy change in the transformation. This energy release is coupled to ATP formation (see Box 7.25). 

Driving Force of Base-Mediated and Acid-Catalyzed Ester Hydrolyses... 

Base-mediated ester hydrolyses have a high driving force. This is because of the acid/base reaction between the carboxylic acid formed in the reaction, and the base used as the reagent. The resonance stabilization of the carboxylate is approximately 30 kcal/mol, which means a gain of about 16 kcal/mol compared to the starting material, the carboxylic ester (resonance stabilization 14 kcal/mol according to Table 6.1). Accordingly, the hydrolysis equilibrium lies completely on the side of the carboxylate. 

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