UVA-irradiated pheomelanin alters the structure of catalase and decreases its activity in human skin

Abstract

More than 40 years ago Aronoff showed that catalase structure and activity is seriously affected by photo-oxidation of its own substrate, hydrogen peroxide, owing to cleavage of its porphyrin active site. Here we support the results of Maresca et al. (in this issue) and expand on them by using structural modeling of native catalase and its photo-oxidation product, where both methionine and tryptophan residues are oxidized, yielding a deactivated enzyme.