Selenium-containing compounds protect DNA from single-strand breaks caused by peroxynitrite

rate constant was recently determined to be 2.8 1 106 M01 s01 (H. Masumoto, R. Kissner, W. H. Koppenol, and H. Sies,Peroxynitrite (ONOO0/ONOOH) is a powerful oxi-unpublished work). Selenium is an essential dietary tracedant that can induce mutations and cause single-element, which is incorporated as selenocysteine into thestrand breaks in plasmid supercoiled DNA. The sele-antioxidant enzyme glutathione peroxidase. Selenium maynium-containing compound ebselen rapidly reacts also be incorporated in the form of selenomethionine intowith peroxynitrite. Therefore, ebselen [2-phenyl-1,2-tissue proteins such as hemoglobin, plasma proteins, orbenzisoselenazol-3(2H)-one] and other selenium-con-keratin. Therefore, we studied here the effect of some sele-taining molecules, selenomethionine and selenocys-nium-containing compounds such as ebselen, selenomethi-tine, were studied as agents protecting DNA from onine, and selenocystine in comparison with their sulfur-single-strand breaks induced by peroxynitrite. Seleno- containing analogs methionine and cystine on the single-methionine and selenocystine protected DNA from sin- strand breaks of DNA caused by peroxynitrite. gle-strand breaks more effectively than their sulfur The single-strand breaks of the supercoiled plasmid analogs, methionine and cystine, and they also were more effective than glutathione or the hydroxyl radi-cal scavenger mannitol. These results suggest that se