Active Oxygen Species Involved in the Dye-Sensitized Photoinactivation of Mushroom Tyrosinase

Kirk L. Parkin, Susan E. Lowum

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4 Scopus citations


Active oxygen species were responsible for affecting the inactivation of native mushroom tyrosinase at pH 7.0 in photodynamic systems containing rose bengal and riboflavin. The effects of scavengers, quenchers, and D2O indicated that H2O2and O2-were the primary active oxygen species generated by the riboflavin-sensitized reaction, and 1O2was the primary species generated by the system containing rose bengal. Diazabicyclo[2.2.2]octane (DABCO), Hepes, and Mops accelerated tyrosinase inactivation, and this was attributed to their ability to form secondary radical adducts or generate free radicals in the presence of copper. The effects of $$OH scavengers and the chelators, EDTA, phytate, and desferrioxamine mesylate (DFOM), indicated that (1) bulk-phase metal-driven Fenton reactions were not responsible for tyrosinase photoinactivation and (2) site-specific generation of $$OH from a copper-driven Fenton reaction played a role in enzyme inactivation.

Original languageEnglish (US)
Pages (from-to)1297-1302
Number of pages6
JournalJournal of agricultural and food chemistry
Issue number6
StatePublished - Jun 1990
Externally publishedYes


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