Malate dehydrogenase (mdh) belongs to the LDH/MDH superfamily and MDH type 1 family. This enzyme catalyzes the conversion of malate into oxaloacetate (using NAD+) and vice versa (this is a reversible reaction). Malate dehydrogenase is also involved in gluconeogenesis, the synthesis of glucose from smaller molecules. Recombinant E.coli mdh protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.