Page 381 - Thermodynamics of Biochemical Reactions

Use of Semigrand Partition Functions 381

(d) Use r ' to calculate A, Go at pH 5. The partition function that is evident in the calculation of gacetate can be printed in
traditional form.

- 3 pH rt log(10)-369.31 4 pH r f log(10)-396.45
Q rf + e- rl

The numerical value of the partition function for acetate at pH 5 is given by

49
7.85988 10

Since G ' =-RTlnr I,
-8.31451*.29815*Log[E~[-(-369.31+3*r*t*Log[101pH~/~r*t~1+Exp~-
(-396.45+4*r*t*Log[lO]~H)/(r*t)ll/.r->8.31451/.t->.29815/.pH->5
-284.805

Thus the semigrand partition function contains all the information on the thermodynamics of the system containing acetate at
a specified pH.

11.2 (a) Calculate the further transformed Gibbs energies of formation of G6P, F6P, and F16BP at pH 7, I = 0, [ATP]
= 10-4M, and [ADP] = 10-2M at 298.15 K. (b) Calculate the further transformed Gibbs energy of formation of the
pseudoisomer group. (c) Calculate the equilibrium mole fractions for G6P, F6P, and F16BP. (d) Repeat this calculation at
[ATP] = 10-2M, and [ADP] = 10-2M at 298.15 K.

(BasicBiochemData2 has to be loaded)

(a) Calculate the standard transformed Gibbs energies of formation of the reactants at pH 7 and zero ionic strength

gpatp=atp/.pH->7/.is->O
-2292.61

gpadp=adp/.pH->7/.is->O

-1428.93

gpglucose6phos=glucose6phos/.pH-~7/.is->O
-1325.

-1321.71

gpfructosel6phos=fructosel6phos/.pH-~7/.is-~O
-2202.84