Idha, also known as D-lactate dehydrogenase, belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family. In enzymology, a D-lactate dehydrogenase (cytochrome) is an enzyme that catalyzes the chemical reaction. Thus, the two substrates of this enzyme are (D)-lactate and ferricytochrome c, whereas its two products are pyruvate and ferrocytochrome c. Recombinant E.coli IdhA protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.