Isocitrate epimerase

This number indicates that it is an isomerase, specifically a racemase or epimerase that acts on hydroxy acids and their derivatives, namely isocitrate.

[1] Isocitrate epimerase specifically catalyzes the reversible reaction:[2] which can also be described as Isocitrate epimerase was originally isolated from the fungal cell-free extract of Penicillium purpurogenum [3], where it was discovered due to the excess accumulation of L-alloisocitric acid (D-erythro-isocitrate)—a diastereomer of isocitrate previously not seen in nature.

In order to accumulate L-alloisocitric acid as a fermentation product, P. purpurogenum needed to be grown on citrate supplemented nutrient agar.

[3][4] During this fermentation it was found that the fermentation yield of L-alloisocitric acid was capable of “exceeding 70% without producing any other stereoisomers of isocitiric acid or other metabolites”.

[3] This enzyme has not been heavily studied since first being identified in 1982, as a result of this there is presently not a crystal structure or active site description for isocitrate epimerase.