(a) Phosphocreatine (creatine phosphate) is a compound in muscle tissue that serves as a reservoir of high-energy phosphate. It reacts with ADP to replenish ATP stores in muscle:

The ΔG°´ for this reaction is 212.5 kJ mol^–1 (23.0 kcal mol^–1). Calculate the ΔG°´ for the hydrolysis of phosphocreatine. Is phosphocreatine a “high-energy” compound?

(b) Using resonance structures of creatine and phosphocreatine, explain why the hydrolysis of phosphocreatine releases a lot of energy.

Transcribed Image Text:

-O H NH₂ -CH₂CO₂+ ADP CH3 phosphocreatine NH₂ H₂N-CN-CH₂CO₂ + ATP CH3 creatine