Glutathione S-transferase mu 1 isoform 2, also known as GSTM1, is a glutathione S-transferase that belongs to the mu class. GSTs (glutathione S-transferase) are differentially expressed in lung, liver and kidney tissue and, notably, three isoforms (GSTA1-1, GSTA1-4 and GSTM1) localize to the mitochondria in addition to the cytoplasm. The GSTM1 of enzymes functions in the detoxification of electrophilic compounds, including carcinogens, therapeutic drugs, environmental toxins and products of oxidative stress, by conjugation with glutathione. Recombinant human GSTM1 protein, fused to His-tag at N-terminus, was expressed in E.coli.