Use of a peptide containing an oxidized methionine residue to ameliorate the effects of oxidative stress in human skin. A short polypeptide containing an oxidized methionine at its C-terminus is shown to inhibit the production of Sunburn Cells in living skin models and to upregulate methionine sulfoxide reductase. Cosmetically acceptable compositions and methods of using the polypeptide are disclosed. The oxidized peptide may repair oxidized alpha 1-antitrypsin, which, in turn, inhibits breakdown of connective tissue by elastase. This effect may have wide ranging ramifications, including, for example, repair of sun damaged skin and treatment of emphysema.
