The amino acid cysteine is oxidized by horseradish peroxidase, and the water-soluble carotenoid crocin is bleached by cooxidation. The monophenol p-hydroxyacetophenone stimulates oxygen uptake, cysteine oxidation and crocin bleaching, whereas its concentration does not change. Superoxide dismutase significantly enhances all these oxidative reactions. Addition of H2O2 is not required for these peroxidase-catalyzed oxidations.
Carotenoids Cysteine