Page 334 - Thermodynamics of Biochemical Reactions

334 Mathernatica Solutions to Problems

{-149.566, -204.627, 59.4359)

nob={ 0.1,0,01
{O.l, 0, 0)

equcalcc [ab,lnkb,nobl

{0.000124334, 0.0998757, 0.0998757)

This problem can also be solved using the stoichiometric number matrix. Water is omitted from the stoichiometric number
matrix, and so the transposed stoichiometric number matrix is given by

tnub={{-l,l,l11;
TableForm [ tnubl

-1 1 1

The transformed Gibbs energy of reaction is given by

tgeGlc+tgeHPO4-tgeG1cP
-10.87

lnkrb={(-1/(8.31451*.29815))*(-10.87)1
{4.38488)

equcalcrx [tnub, lnkrb, nobl
{0.000124334, 0.0998757, 0.09987571

Thus the concentration of G6P2- is 1.24 x~O-~.

6.8 A liter of aqueous solution contains 0.02 mol phosphate and acid andNaCl are added to bring it to pH 7, and 0.2.5 M
ionic strength. What is the equilibrium composition in terms of phosphate species?

(BasicBiochemData2 has to be loaded)

Since H and Mg are not conserved, the conservation matrix is

as= C { 1,1,1) 1

{{I, 1, 1))

where the species are H2 PO4 -, HP04 2-, and MgHP04. The transformed Gibbs energies of these three species at 2.5 O C, pH
7, pMg 3, and I = 0.25 M have been calculated by Alberty and Goldberg (1992), and they can be used to calculate

1nk~-(1/(8.31451*.29815))*{-1056.58,-1058.57,-1050.441
{426.217, 427.02, 423.74)

The equilibrium concentrations of the three phosphate species are given by