Question

Phosphoenol pyruvate is one of the two phosphoryl group donors in the synthesis of ATP during glycolysis. In humans, the steady-state concentration of ATP is 2.24 mM, that of ADP is 0.25 mM, and that of pyruvate is 0.051 mM. Calculate the concentration of PEP at 25 degrees Celsius, assuming the pyruvate kinase reaction is at equilibrium.

Answer 1

To calculate the concentration of PEP at 25 degrees Celsius, use the equilibrium constant (Keq) of the pyruvate kinase reaction and the given concentrations of ATP, ADP, and pyruvate.

The concentration of PEP at 25 degrees Celsius can be calculated using the equilibrium constant (Keq) of the pyruvate kinase reaction and the concentrations of ATP, ADP, and pyruvate.

The equation for the pyruvate kinase reaction is: PEP + ADP ⇌ pyruvate + ATP.

At equilibrium, the ratio of the concentrations of products to reactants is equal to the Keq value.

Keq = [pyruvate][ATP] / [PEP][ADP]

By rearranging the equation and substituting the given concentrations of ATP, ADP, and pyruvate, you can solve for the concentration of PEP.

PEP = ([pyruvate][ATP]) / ([ADP] * Keq)

Substituting the values: PEP = (0.051 mM * 2.24 mM) / (0.25 mM * Keq)

Since the Keq value is not provided, you cannot calculate the exact concentration of PEP without it. However, you can calculate the concentration of PEP given different values of Keq.