Glutathione synthetase promotes the reduction of arsenate via arsenolysis of glutathione

► Glutathione synthetase promotes the reduction of arsenate to the more toxic arsenite. ► GS facilitates arsenate reduction by catalyzing the arsenolysis of glutathione. ► Arsenolysis of GSH yields ADP-arsenate. ► Arsenic in ADP-arsenate is readily reduced to arsenite by glutathione.