Biochemistry The citric acid cycle is a hub of energy transformation. Which citric acid cycle enzyme produces ATP by substrate level phosphorylation? A Aconitase B Succinate dehydrogenase C Isocitrate dehydrogenase D Succinate thiokinase 💡 Explanation The citric acid cycle is a hub of energy transformation. Which citric acid cycle enzyme produces ATP by substrate level phosphorylation? ✓ Correct Answer: D. Succinate thiokinase