Metallothioneins (MTs) are a family of low molecular weight, cysteine rich heavy metal binding proteins with multifunction, such as metal detoxification and antioxidation, and are involved in a number of cellular processes including gene expression, apoptosis, proliferation and differentiation. However, high yield expression of human MT in Escherichia coh has not been established effectively. To produce large amounts of human MT protein at low cost, recombinant human metallothionein 2A (MT2A) protein with an N-terminal GST tag was successfully expressed at high levels in soluble form in E coli and high purification of it was established by affinity chromatography under native conditions. The final yield was about 5 mg of the recombinant MT2A per liter of bacterial culture with the purity of 97.9%. Chemical and functional characteristics analysis of the recombinant human MT2A exhibited intact metal binding ability, hydroxyl radical scavenging ability and significant protective role against DNA damage caused by UVC radiation. Establishment of highly purified recombinant human MT2A protein with native characteristics at low cost would improve its function study and wide applications in protecting against oxidative damage and UV radiation. (c) 2006 Elsevier Inc. All rights reserved.