Skip to content
← Theoretical 1

Q1 - Stereochemistry of Citrate and Isocitrate in the Aconitase Reaction

Theoretical 1 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Bioenergetics & Central Metabolism Overview

The citric acid cycle is central to metabolism, for the supply energy and various key compounds. In citric acid cycle, the enzyme aconitase catalyzes the reversible conversion between citrate and isocitrate. In this reaction, OH group at C3 and H group at C4 of citrate are removed as water, thereafter a water molecule is added back in a reverse manner to generate isocitrate (Figure 1). However, OH group is never added at C2.

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. Citrate has enantiomers.
B. Isocitrate has enantiomers.
C. Two:CH2COO- groups are stereochemically equivalent when citrate is free in solution.
D. Two:CH2COO- groups are stereochemically equivalent when citrate is bound to aconitase.
← Back to Theoretical 1 Next: Q2 →

Question reproduced from IBO 2020, Theoretical Exam 1, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)