Cell survival is reliant on GSH scavenging of ROS and its role in GPx activity [1]; however, GSH may also utilize other lesser-studied mechanisms to protect cells against metal-mediated oxidative damage. Because glutathione increases survival of copper-treated cells, it has been proposed that glutathione–copper binding reduces copper toxicity in cells [54], and a GSH–copper complex was detected in cytoplasmic extracts of human adenocarcenoma cells [55]. Complexation of GSH with Hg2+ and Ag+ is also known to inhibit glutathione oxidation by H2O2 [56]. Clinical trials have also shown that sulfur compounds protect cellular components from oxidative damage [38–40,49], and antioxidant activity of these compounds has often been attributed to ROS scavenging [1]. Our previous research demonstrated that copper coordination is required for the inhibition of copper-mediated oxidative DNA damage by selenium antioxidants, including selenomethionine and selenocystine [57], but no work has explored the role of metal coordination on biological antioxidant activity of glutathione and other sulfur-containing antioxidants