Demonstration of 2-Oxoglutarate:Glyoxylate Carboligase Activity in Tetrahymena pyriformis

A 2-oxoglutarate:glyoxylate carboligase, requiring thiamine pyrophosphate and magnesium, was demonstrated in Tetrahymena pyriformis and appears to be located in the mitochondrial fraction. The product of the reaction α-hydroxy-β-ketoadipate decarboxylates in the presence of acid to δ-hydroxylevulinate. The latter was identified in the acidified reaction mixtures. The carboligase activity varies coordinately with 2-oxoglutarate dehydrogenase. The two activities may reside in the same complex as in beef-heart mitochondria.