Question

The hydrolysis of ATP, ATP(aq) + H2O(l) → ADP(aq) + Pi(aq) ΔG°rxn = -30.5 kJ is often used to drive nonspontaneous processes - such as muscle contraction and protein synthesis - in living organisms. The nonspontaneous process to be driven must be coupled to the ATP hydrolysis reaction. For example, suppose the nonspontaneous process is A + B → AB (ΔG° positive). The coupling of a nonspontaneous reaction such as this one to the hydrolysis of ATP is often accomplished by the following mechanism. A + ATP + H2O → A-Pi + ADP A-Pi + B → AB + Pi ______________________ A + B + ATP + H2O → AB + ADP + Pi As long as ΔGrxn° for the nonspontaneous reaction is less than 30.5 kJ, the reaction can be made spontaneous by coupling in this way to the hydrolysis of ATP. Suppose that ATP is to drive the reaction between glutamate and ammonia to form glutamine. Part A Calculate K for the reaction between glutamate and ammonia. (The standard free energy change for the reaction is +14.2 kJ/mol. Assume a temperature of 298 K.) Express your answer using three significant figures. Part B The glutamate and ammonia reaction can couple with the hydrolysis of ATP (such as shown above). What is ΔG°rxn for this coupled reaction? Express your answer using three significant figures. Part C What is K for this coupled reaction?

          The hydrolysis of ATP,
ATP(aq) + H2O(l) → ADP(aq) + Pi(aq) ΔG°rxn = -30.5 kJ
is often used to drive nonspontaneous processes - such as muscle
contraction and protein synthesis - in living organisms. The
nonspontaneous process to be driven must be coupled to the ATP
hydrolysis reaction. For example, suppose the nonspontaneous
process is A + B → AB (ΔG° positive). The coupling of a
nonspontaneous reaction such as this one to the hydrolysis of ATP
is often accomplished by the following mechanism.
A + ATP + H2O → A-Pi + ADP
A-Pi + B → AB + Pi
______________________ 
A + B + ATP + H2O → AB + ADP + Pi
As long as ΔGrxn° for the nonspontaneous reaction is less than
30.5 kJ, the reaction can be made spontaneous by coupling in
this way to the hydrolysis of ATP. Suppose that ATP is to drive the
reaction between glutamate and ammonia to form glutamine.
Part A
Calculate K for the reaction between glutamate and
ammonia. (The standard free energy change for the reaction is
+14.2 kJ/mol. Assume a temperature of 298 K.)
Express your answer using three significant figures.
Part B
The glutamate and ammonia reaction can couple with the
hydrolysis of ATP (such as shown above). What
is ΔG°rxn for this coupled reaction?
Express your answer using three significant figures.
Part C
What is K for this coupled reaction?

Added by Courtney J.

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