Glutathione S-transferase mu 5, also known as GSTM5, is member of the glutathione s-transferase (GST) family of proteins. There are eight families of GST proteins, namely alpha, kappa, mu, omega, pi, sigma, theta and zeta, each of which is composed of proteins that have a variety of functions throughout the cell. GSTM5 plays an important role in detoxification. Recombinant human GSTM5 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.