Evidence for NADH‐ and NADPH‐linked Glutamate Dehydrogenases in Trypanosoma cruzi Epimastigotes*

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Abstract
Two glutamate dehydrogenases, NADH-linked (EC 1.2.1.2) and NADPH-linked (EC 1.2.1.4) were isolated from the epimastigote forms of T. cruzi and purified. Both enzymes exist as hexamers. The MW of the native NADH- and NADPH-linked glutamate dehydrogenases were estimated to be 360,000 and 265,000, respectively, and those of the subunits to be 58,000 and 43,000, respectively. The isoelectric point of the NADH-linked dehydrogenase is at pH 5.25 and that of the NADPH-linked enzyme at pH 5.1. The activities of both enzymes are regulated by product inhibition. Purine nucleotides were potent inhibitors of the NADH-linked glutamate dehydrogenase.