Involved in resistance to arsenate (PubMed:3021763, PubMed:8003492, PubMed:7577935). Catalyzes the reduction of arsenate [As(V)] to arsenite [As(III)] (PubMed:8003492, PubMed:7577935, PubMed:14592722). The resulting arsenite is then extruded from the cell via the ArsAB transport system (Probable). [glutaredoxin]-dithiol + arsenate + glutathione + H(+) = arsenite + glutathionyl-S-S-[glutaredoxin] + H2O Inhibited by the thiol reagents iodoacetate (IAA) and N-ethylmaleimide (NEM) (PubMed:7577935). Activity is rapidly inactivated by the histidine-modifying reagent diethylpyrocarbonate (DEPC) (PubMed:8969183). kcat is 0.53 sec(-1) with arsenate as substrate. kcat is 0.218 sec(-1) with Grx2 as substrate. Optimum pH is 6.3-6.8. Monomer in solution. Belongs to the ArsC family.