The complex structures of isocitrate dehydrogenase from Clostridium thermocellum and Desulfotalea psychrophila suggest a new active site locking mechanism

▸ Focus is on a thermophilic (CtIDH) and cold active (DpIDH) isocitrate dehydrogenase. ▸ Biochemical characterization and three new IDH crystal structures are presented. ▸ CtIDH has many ionic interactions and hydrogen bonds, which explain the Tm of 68 °C. ▸ Prokaryotic IDH subfamily II seems to have a unique locking mechanism. ▸ The large domain is locked to the small domain and NADP+ is also directed correctly.