On the Nature of the Enzyme which Catalyzes a Synergistic Decarboxylation of α-Ketoglutarate and Glyoxylate

Abstract

An enzyme which catalyzes a synergistic decarboxylation of α-ketoglutarate and glyoxylate, a carboligase reaction, was purified from the extract of Rhodopseudornonas spheroides and also from the extract of acetone-dried rat liver mitochondria. The carboligase activity was always associated with α-ketoglutarate decarboxylase activity even after several steps of purification. The α-ketoglutarate dehydrogenase complex prepared from pig heart also catalyzed the carboligase reaction between α-ketoglutarate and glyoxylate or some other aldehydes. Aldehydes, in turn, inhibited the α-keto-glutarate dehydrogenase activity as measured by the reduction of NAD⁺. The α-keto-glutarate dehydrogenase subcomplex fraction derived from α-ketoglutarate dehydro-genase complex by resolution with urea also showed the carboligase activity.
It was assumed that the enzyme catalyzing the synergistic decarboxylation of α-ketoglutarate and glyoxylate is in reality α-ketoglutarate decarboxylase.