Isocitrate Dehydrogenase from Escherichia coli displays High Solvent Tolerance during NADPH generation

Abstract

Isocitrate dehydrogenase (ICDH) is the key enzyme of Krebs cycle where it catalyzes the NAD(P)+-dependent oxidative decarboxylation of isocitrate to α-ketoglutarate. Despite the identification and characterization of several ICDHs from different organisms, the solvent and salt tolerance ability of these enzymes have not been explored. In the current work, the NADPH-dependent isocitrate dehydrogenase from E. coli (EcICDH) has been investigated for its activity under varying solvent and salt concentrations. EcICDH retained high activity in the presence of up to 50% EtOH and iso-propanol and tolerates high KCl concentrations up to 150 mM. Furthermore, the isocitrate/EcICDH system is evaluated for the NADPH generation during the reduction of 2-tetralone, a seven-membered cyclic imine, and 2-nitro chalcone substrates with naphthol, imine, and an ene reductase, respectively to show its utility.