IDH1 is one of three isocitrate dehydrogenases that catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate. IDH1 catalyzes the third step of the citric acid cycle, which involves the oxidative decarboxylation of isocitrate, forming α-ketoglutarate and CO2 in a two step reaction. The first step involves the oxidation of isocitrate to the intermediate oxalosuccinate, while the second step involves the production of α-ketoglutarate. During this process, either NADH or NADPH is produced along with CO2. IDH1 is expressed in a wide range of species and also in organisms that lack a complete citric acid cycle. Recently, an inactivating mutation of IDH1 has been implicated in glioblastoma.
