Tyrosinase reactivity in a model complex: An alternative hydroxylation mechanism

被引:279
作者
Mirica, LM
Vance, M
Rudd, DJ
Hedman, B [1 ]
Hodgson, KO
Solomon, EI
Stack, TDP
机构
[1] Stanford Univ, Dept Chem, Stanford, CA 94305 USA
[2] Stanford Linear Accelerator Ctr, Stanford Synchrotron Radiat Lab, Stanford, CA 94309 USA
关键词
D O I
10.1126/science.1112081
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The binuclear copper enzyme tyrosinase activates O-2 to form a mu-eta(2):eta(2)-peroxodicopper(II) complex, which oxidizes phenols to catechols. Here, a synthetic mu-eta(2):eta(2)-peroxodicopper(II) complex, with an absorption spectrum similar to that of the enzymatic active oxidant, is reported to rapidly hydroxylate phenolates at -80 degrees C. Upon phenolate addition at extreme temperature in solution (-120 degrees C), a reactive intermediate consistent with a bis-mu-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.
引用
收藏
页码:1890 / 1892
页数:3
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