NFNB, also known as NFSB, shows the ability to reduce quinines. This protein is an enzyme for activating prodrugs in antibody directed enzyme prodrug therapy. It also capable of reducing nitrofurazone, quinones and the anti-tumor agent CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide). The reduction of CB1954 results in the generation of cytotoxic species. Recombinant E.coli NFNB protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.