Formation of hydrogen peroxide from the photooxidation of tryptophan and related substances

Near-ultraviolet (300 to 400 nanometers) irradiation of saturated, oxygenated solutions of tryptophan in the absence of added sensitizer gives rise to substances that have various biological effects on isolated cells, including mutagenicity and selective lethality to recombination-deficient bacterial mutants. One of these biologically active products has been identified as H2O2, on the basis of spectrometric, chromatographic, chemical, and biological properties. Now H2O2 has been shown to account for the biological activities mentioned above. Similar irradiation of lysozyme also has been found to produce H2O2. Finally, sensitizers such as N-formylkynurenine and orthoformamidoacetophenone have been shown to promote H2O2 formation when irradiated with tryptophan, lysozyme, or methionine