Absence of α‐Ketoglutarate Dehydrogenase Activity and Presence of CO₂‐Fixing Activity in Plasmodium falciparum Grown In Vitro in Human Erythrocytes

Plasmodium falciparum‐infected human erythrocytes grown in vitro do not release ¹⁴CO₂, when incubated in the presence of [1‐¹⁴C]glutamate, despite the presence of glutamate dehydrogenase, implying the absence of α‐ketoglutarate dehydrogenase activity and the lack of functional tricarboxylic acid cycle in the human malaria parasite. Cultures incubated with [¹⁴C]bicarbonate, however, fix CO₂ into acid‐stable metabolites; CO₂ fixation proceeds linearly for up to two hours after an initial brief lag and may contribute appreciably to the metabolism of the parasite.