Page 277 - Thermodynamics of Biochemical Reactions

Chapter 4 Thermodynamics of Biochemical Reactions at Specified pH

4.1 (a) Calculate Of Go for the species of ATP at 298.15 K, pH 7, and I = 0.25. (b) Calculate a,G'" for ATP at 298.15 K,
pH 7, and I = 0.25 M. (c) Plot &Go for ATP at 298.15 K, and I = 0.25 M versus pH. (d) Plot N,for ATP at I = 0.25 M
versus pH.

4.2 (a) Calculate &H0 for ATP at 298.15 K, pH 7, and I = 0.25 M. (b) Plot AfHo for ATP at 298.15 K, and I = 0.25 M
versus pH. (c) Calculate the standard transformed enthalpy of formation at pH 7 and 0.25 M ionic strength at several
temperatures in the range 273 K to 3 13 K.

4.3 (a) Calculate AI G'" in kJ mol-I at 298.15 K, pH 7, and I = 0.25 M for ATP + H20 = ADP + Pi. (b) Calculate the
corresponding Ar H'" . (c) Calculate the corresponding A,S" in J K-'mo1-l. (d) Calculate logK. (e) Plot the values of
each of these properties versus pH at I = 0.25 M on the assumption that the standard enthalpies of formation of ions are
independent of temperature.

4.4 (a) For ATP + H2 0 = ADP + Pi plot K' versus pH at ionic strengths of 0, 0.10, and 0.25 M. (b) Plot IogK' versus pH
at ionic strengths of 0, 0.10, and 0.25 M. (c) Plot K versus ionic strength at pHs 5, 7, and 9.

4.5 For ATP + H2 0 = ADP + Pi plot A,N, versus pH at ionic strengths of 0, 0.10, and 0.25 M.

4.6 Calculate the standard transformed Gibbs energies of reaction for ATP + H2 0 = ADP + Pi at temperatures of 283.15 K,
298.15 K, and 313.15 K, at pHs 5, 6,7, 8, 9, and ionic strengths of O,O.lO, and 0.25 M.

4.7 Calculate the standard transformed Gibbs energies of reaction at 298.15 K and the experimental pH and ionic strength
for the reactions in the Goldberg and Tewari series of six critical reviews for which all the reactants are in BasicBiochem-
Data2. Compare the calculated standard transformed Gibbs energies of reaction with the experimental values. At present
there is not enough information to calculate the effects of temperature and metal ions, and so these effects are ignored. The
three steps in this process are: (a) Make a table of the calculated standard transformed Gibbs energies of reaction. (b) Make
a table of the relevant data in the Goldberg and Tewari Tables. (c) Make a table of the differences between the values of the
standard transformed Gibbs energies of reaction calculated in part (a) and the experimental values in the Goldberg and
Tewari tables.

4.8 Calculate the standard transformed reaction Gibbs energies, apparent equilibrium constants, and changes in the binding
of hydrogen ions for the ten reactions of glycolysis at 298.15 K, pHs 5, 6, 7, 8, and 9, and ionic strengths 0, 0.10, and 0.25
M. Also calculate these properties for the net reaction.

4.9 Calculate the standard transformed reaction Gibbs energies, apparent equilibrium constants, and changes in the binding
of hydrogen ions for the four reactions of gluconeogenesis that are different from those in glycolysis at 298.15 K, pHs 5, 6,
7, 8, and 9 and ionic strengths 0, 0.10, and 0.25 M. Also calculate the properties of the net of pyruvate carboxylase and
phosphoenolpyruvate carboxykinase reactions and the net reaction of gluconeogenesis.

4.10 Calculate the standard transformed reaction Gibbs energies, apparent equilibrium constants, and changes in the binding
of hydrogen ions for the pyruvate dehydrogenase reaction and the nine reactions of the citric acid cycle at 298.15 K, pHs 5,
6, 7, 8, and 9 and ionic strengths 0, 0.10, and 0.25 M. Also calculate these properties for the net reaction of the citric acid
cycle, the net reaction for pyruvate dehydrogenase plus the citric acid cycle, and the net reaction for glycolysis, pyruvate
dehydrogenase, and the citric acid cycle.

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