Consider the following information: phosphoenolpyruvate → pyruvate
ΔG°' = −61.9 kJ/mol
ADP + P_i → ATP
ΔG°' = +30.5 kJ/mol
How many molecules of ATP might theoretically have been produced when coupled to the conversion of one molecule phosphoenolpyruvate to pyruvate?

Question

Quizplus · Accepted Answer

The overall reaction can be written as: phosphoenolpyruvate + ADP + P_i → pyruvate + ATP To calculate the ΔG°' of the overall reaction, we just need to add the individual ΔG°' values: ΔG°' overall = ΔG°' PE → pyruvate + ΔG°' ADP + P_i → ATP ΔG°' overall = (-61.9 kJ/mol) + (+30.5 kJ/mol) = -31.4 kJ/mol Since the ΔG°' is negative, the overall reaction is exergonic and can potentially drive the synthesis of ATP. A negative ΔG°' typically means that a reaction is spontaneous and can produce free energy that can be harnessed to drive another reaction. The ΔG°' value for the conversion of ADP to ATP is +30.5 kJ/mol, which means that the reaction cannot proceed spontaneously. However, coupling it with a reaction that has a more negative ΔG°' makes it possible to achieve a net negative ΔG and synthesize ATP. In this case, the net ΔG°' for the overall reaction is -31.4 kJ/mol. To synthesize one molecule of ATP, you need a net input of 30.5 kJ/mol. Therefore, it is possible to synthesize two molecules of ATP using the conversion of one molecule of phosphoenolpyruvate to pyruvate.

Consider the Following Information: Phosphoenolpyruvate → Pyruvate