The reaction that follows is catalyzed by isocitrate dehydrogenase and occurs in two steps, the first of which (step A) is formation of an unstable intermediates (shown in brackets).


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d. To what class of enzymes does isocitrate dehydrogenase, the enzyme that catalyzes this reaction, belong?

Verified step by step guidance

1. Identify the type of reaction catalyzed by isocitrate dehydrogenase. This enzyme is involved in the citric acid cycle, where it catalyzes the oxidative decarboxylation of isocitrate.
2. Understand that oxidative decarboxylation involves the removal of a carboxyl group, releasing carbon dioxide, and the oxidation of the substrate, which typically involves the transfer of electrons to a cofactor such as NAD+ or NADP+.
3. Recognize that enzymes that catalyze oxidation-reduction reactions are classified as oxidoreductases. These enzymes facilitate the transfer of electrons from one molecule (the reductant) to another (the oxidant).
4. Consider the specific role of isocitrate dehydrogenase in the citric acid cycle, where it helps convert isocitrate into alpha-ketoglutarate, producing NADH or NADPH in the process.
5. Conclude that isocitrate dehydrogenase belongs to the class of oxidoreductases, as it catalyzes an oxidation-reduction reaction involving the transfer of electrons.

Key Concepts

Enzyme Classification

Enzymes are classified into six main categories based on the type of reaction they catalyze: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. Isocitrate dehydrogenase is specifically classified as an oxidoreductase, which means it catalyzes oxidation-reduction reactions, transferring electrons from one molecule to another.

Isocitrate Dehydrogenase Function

Isocitrate dehydrogenase plays a crucial role in the citric acid cycle (Krebs cycle), where it catalyzes the conversion of isocitrate to alpha-ketoglutarate. This reaction involves the decarboxylation of isocitrate and the reduction of NAD+ to NADH, highlighting its importance in cellular respiration and energy production.

Enzyme Catalysis Mechanism

Enzyme catalysis involves the lowering of activation energy for a reaction, allowing it to proceed more quickly. In the case of isocitrate dehydrogenase, the enzyme stabilizes the transition state and facilitates the formation of unstable intermediates, which are crucial for the reaction's progression and efficiency.