The reaction phosphoenolpyruvate ADP H rightarrow pyruvate

The reaction phosphoenolpyruvate ADP + H+ rightarrow pyruvate + ATP has a delta G^0\' = -31.4 kJ/mol and a delta G\' = -16.7 kJ/mol under physiological conditions. What do these numbers suggest about this reaction.

Solution

These numbers suggest that, when the reaction happens 31.4 kJ/mol energy has been released at the real-world condition; Whereas, if the same reaction happened at standard conditions (concentration 1.0M, pressure 1.0 atm and Temperature 25°C), 16.7 kJ/mol energy has been released.

Both G⁰\' and G\' denotes free energy changes of a reaction. The only difference between these G⁰\' and G\' is: G⁰\' gives the free energy value under standard concentration, pressure and Temperature at 1.0M, 1.0 atm and 25°C respectively; whereas G\' gives the free energy value under the real conditions. When the reaction releases energy it will be shown with “-“ sign and when the reaction absorbs the energy then it will be shown with “+” sign.