BICH 441 HONORS, SPRING 2006
Problem Set #1
01/19/06
1. PEP carboxykinase (G&G p709) catalyzes the reaction:
Oxaloacetate + GTP --> phosphoenolpyruvate + GDP + CO2
Calculate the std.dG for the reaction given:
PEP + H2O --> Pyr + Pi std.dG = -62 kJ/mol
OAA --> Pyr + CO2 std.dG = -21 kJ/mol
GTP + H2O --> GDP + Pi std.dG = -31 kJ/mol
Where oxaloacetate = OAA, pyruvate = Pyr, phosphoenolpyruvate = PEP
answer = +10 kJ/mol
2. Calculate the standard free energy change,
std.dG, and the actual free energy change, dG,
for the reaction catalyzed by
phosphofructokinase-1, given:
K' = 1x103
[Frc6P] = 60µM
[Frc16bisP] = 12µM
[ATP] = 1.92mM
[ADP] = 0.91mM
R = 8.31 J/degK.mol
T = 310K
std.dG = -17.8 kJ/mol
dG = -23.9 kJ/mol