Malic enzyme : Its purification and characterization from Mucor circinelloides and occurrence in other oleaginous fungi

Malic enzyme was purified 43-fold from Mucor circinelloides. The enzyme was dependent on Mg2+ or Mn2+ for activity, was not active with Dmalate and had a pH optimum at 7.8. The apparent Km values for malate and NADP+ were 488 ΜM and 41 Μm respectively. The Mr of the native enzyme was 160 kDa. Five metabolic analogues of malate: oxaloacetate, tartronic acid, 1-methylenecyclopropane trans-2,3-dicarboxyIic acid, malonic acid and glutaric acid, were found to inhibit malic enzyme activity at 10 mM. Four oleaginous fungi, Mucor circinelloides, Mortierella alpina, Mortierella elongata and Pythium ultimum, were also examined, all possessed a soluble malic enzyme, two also possessed a microsomal malic enzyme