Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 9

Succinate Oxidation. The oxidation of succinate to fumarate is an important cellular reaction because it is one of the steps in the tricarboxylic acid (TCA)cycle (see Chapter 10). The two hydrogen atoms that are removed from succinate are accepted by a coenzyme molecule called flavin adenine dinucleotide (FAD), which is thereby reduced to FADH 2 :
(1)
G°' for Reaction 5-32 is 0 cal/mol.
(a)If you start with a solution containing 0.01 M each of succinate and FAD and add an appropriate amount of the enzyme that catalyzes this reaction, will any fumarate be formed If so, calculate the resulting equilibrium concentrations of all four species. If not, explain why not.
(b)Answer part a assuming that 0.01 M FADH 2 is also present initially.
(c)Assuming that the steady-state conditions in a cell are such that the FADH 2 /FAD ratio is 5 and the fumarate concentration is 2.5 M, what steady-state concentration of succinate would be necessary to maintain G' for succinate oxidation at 1.5 kcal/mol