EC 2.3.3.1 (Modified from 4.1.3.7 in 2002). Recombinant from E. coli. In 3.2 M ammonium sulphate. Specific activity: 15.5 U/mg (25oC, pH 8.0). Contaminants: aconitase, isocitrate dehydrogenase, L-malate dehydrogenase < 0.001%; NADH oxidase = 0.0016 %. Stable at 4oC for > 2 years.