BIOCHEMISTRY Study Guide - Quiz Guide: Citric Acid Cycle, Mitochondrial Matrix, Oxaloacetic Acid

The first step in the citric acid cycle of food metabolism isreaction of oxaloacetate with acetyl CoA to give citrate. Propose amechanism, using acid or base catalysis as needed.

Oxaloacetate + Acetyl CoA ----> Citrate

Consider the formation of isocitrate from oxaloacetate and acetate in the tricarboxylic acid cycle. The series of reactions are shown along with their Keq values.

Citrate ⇌ oxaloacetate + acetate Keq= 2.0

Cis-aconitate + H2O ⇌ citrate Keq= 0.07

Isocitrate ⇌ cic-aconitate Keq= 0.5

a. Calculate the Keq overall for the formation of isocitrate.

b. Given R= 1.987 cal/mole*K, calculate ∆G at 38°C for the formation of isocitrate from oxaloacetate and acetate in the tricarboxylic acid cycle.

When citrate is shuttled out of the mitochondria for fatty acid synthesis, the initial reaction by citrate lyase generates which of the following products?

a. Pyruvate and malate

b. AcetylCoA and citrate

c. Citrate and oxaloacetate

d. AcetylCoA and oxaloacetate