Reduces organic and inorganic peroxide substrates. Protects the cell against oxidative stress. Homodimer. A small fraction is associated with the cell membrane. Down-regulated by osmotic shock and ethanol. Not induced by oxidative stress. Mutant is highly sensitive to killing by tert-butyl hydroperoxide (t-BHP) and H(2)O(2). Belongs to the OsmC/Ohr family.