Chapter 15: Q10P (page 520)
The half-reactions involved in the lactate dehydrogenase (LDH) reaction and their standard reduction potentials are
Pyruvate +2H鈦+2e鈦烩啋Lactate
狈础顿鈦+2贬鈦+2别鈦烩啋狈础顿贬+贬鈦
Calculate 鈭咷 at pH 7.0 for the LDH-catalyzed reduction of pyruvate under the following conditions:
- [lactate]/[pyruvate]=1 and [NAD鈦篯/[NADH]=1
- [lactate]/[pyruvate]=160 and [NAD鈦篯/[NADH]=160
- [lactate]/[pyruvate]=1000 and [NAD鈦篯/[NADH]=1000
- Discuss the effect of the concentration ratios in Parts a-c on the direction of the reaction.
Short Answer
In solution (a), the free energy change value at pH 7.0 for the LDH-catalyzed reduction of pyruvate under the given condition is -25.1kJ mol鈦宦.
In solution (b), the free energy change value at pH 7.0 for the LDH-catalyzed reduction of pyruvate under the given condition is 0.
In solution (c), the free energy change value at pH 7.0 for the LDH-catalyzed reduction of pyruvate under the given condition is 9.1 kJ mol鈦宦.
In solution (d), the reaction continues spontaneously in the backward direction.