What is the ΔG°' value for phosphocreatine?

The standard Gibbs free energy change (ΔG°') value for phosphocreatine is approximately -43 kJ/mol, indicating that the hydrolysis of phosphocreatine to creatine and inorganic phosphate is a highly exergonic reaction. This negative value reflects a significant release of energy, which is crucial for cellular processes that require rapid energy supply, especially in muscle tissues during intense activity.

Phosphocreatine serves as a high-energy reservoir in cells, particularly during short bursts of anaerobic exercise. The energy released from the breakdown of phosphocreatine can be used to regenerate ATP from ADP through the action of creatine kinase, thereby maintaining energy homeostasis in cells.

In contrast, ΔG°' values that are less negative or positive would suggest that the reaction is either less favorable or non-spontaneous under standard conditions. Thus, the -43 kJ/mol value for phosphocreatine illustrates its role as a key energy donor in the biological systems where rapid access to energy is needed.