Ddt, also known as D-dopachrome decarboxylase, is an enzyme that catayzes the tautomerization of D-dopachrome to give 5,6-dihyroxyindole(DHI). This protein belongs to the family of lyases, specifically the carboxy-lyases, which cleave carbon-carbon bonds. It shares a homologous amino acid sequence (33 % identical) with the macrophage migration inhibitory factor (MIF) and possesses similar tautomerase activity in addition, it may functions a proinflammatory cytokine. Recombinant mouse Ddt, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.