Malic Enzyme activity was assayed spectrophotometrically at 340nm as described in Mandela and Sauer . The standard reaction mixture contained 50 mM Tris-HCl, 3 mM MnCl2, 5 mM malate, 0.12 mM NADP+, 2.5 mM fumarate. Assay was performed in a Beckman spectrophotometer. The Km value is 1.5 ± 0.6 mM