Question: In frog muscle rectus abdominis, the concentrations of ATP, ADP, and phosphate are 1.25 x 10-3 M,…

In frog muscle rectus abdominis, the concentrations of ATP, ADP,
and phosphate are 1.25 x 10^-3 M, 0.50 x 10^-3
M, and 2.5 x 10^-3 M, respectively.

Calculate the Gibbs free energy change
Δ_rG^o for the hydrolysis of ATP in muscle.

Take the temperature and pH of the muscle as 25 ^oC
and 7, respectively.

For the muscle described, what is the maximal amount of
mechanical work it can do per mol of ATP hydrolyzed?

In muscle, the enzyme creatine phosphokinase catalyzes the
following reaction:

Phosphocreatine + ADP → creatine +
ATP

The standard Gibbs free energy of
hydrolysis of phosphocreatine at 25 ^oC and pH 7 is -43.1
kJ/mol.

Phosphocreatine + H₂O →
creatine + phosphate

Calculate the equilibrium constant of
the creatine phosphokinase reaction.