It's a keto acid, formed during the oxidative decarboxylation of isocitrate to alpha-ketoglutarate, which is catalyzed by the enzyme isocitrate dehydrogenase.
Isocitrate dehydrogenase catalyzes the conversion of isocitrate into a keto acid during the oxidative decarboxylation process that results in alpha-ketoglutarate. A single molecule of this reaction can produce thousands of keto acids.