Thioredoxin(Trx) is a low molecular weight redox protein. Trx contains a redox active disulfide/dithiol group within the conserved Cys-Gly-Pro-Cys active site. It is involved in the first unique step in DNA synthesis. Trx also provides control over a number of transcription factors affecting cell proliferation and death through a mechanism referred to as redox regulation. Recombinant TXN protein, fused to His-tag at N-terminus, was expressed in E. coli.