Chemistry: Tyrosinase reactivity in a model complex: An alternative hydroxylation mechanism

Liviu M. Mirica, Michael Vance, Deanne Jackson Rudd, Britt Hedman, Keith O. Hodgson, Edward I. Solomon, T. Daniel P. Stack

Research output: Contribution to journalArticlepeer-review

Abstract

The binuclear copper enzyme tyrosinase activates O2 to form a μ-η22-peroxodicopper(II) complex, which oxidizes phenols to catechols. Here, a synthetic μ-η2: η2-peroxodicopper(II) complex, with an absorption spectrum similar to that of the enzymatic active oxidant, is reported to rapidly hydroxylate phenolates at -80°C. Upon phenolate addition at extreme temperature in solution (-120°C), a reactive intermediate consistent with a bis-μ-oxodicopper(III)-phenolate complex, with the O-O bond fully cleaved, is observed experimentally. The subsequent hydroxylation step has the hallmarks of an electrophilic aromatic substitution mechanism, similar to tyrosinase. Overall, the evidence for sequential O-O bond cleavage and C-O bond formation in this synthetic complex suggests an alternative intimate mechanism to the concerted or late stage O-O bond scission generally accepted for the phenol hydroxylation reaction performed by tyrosinase.

Original languageEnglish (US)
Pages (from-to)1890-1892
Number of pages3
JournalScience
Volume308
Issue number5730
DOIs
StatePublished - Jun 24 2005
Externally publishedYes

ASJC Scopus subject areas

  • General

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