کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1310291 | 975239 | 2008 | 5 صفحه PDF | دانلود رایگان |
Laccase from Trametes versicolor reduces dioxygen to water. The enzyme is used in green chemistry applications such as the selective oxidation of alcohols in the presence of a suitable mediator (TEMPO) or in biofuel cells. We studied the catalytic mechanism of the enzyme by the stopped-flow and our newly developed rapid-mixing rapid sampling method, which has an experimental dead time of 75 ± 15 μs. Equilibrium and kinetic analyses yielded a reduction potential of 717 ± 5 mV for Type 1 copper center. EPR and low-temperature UV–Vis spectroscopy indicate that oxidation of the blue copper center and OO bond splitting occur within 100 μs, without detectable formation of a peroxide intermediate. These results indicate a rapid internal electron transfer between the various copper centers (>25.000/s) and rapid binding of O2 (kon > 5 × 107 M−1 s−1). Mechanistic aspects of the catalytic cycle are shortly discussed.
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Journal: Inorganica Chimica Acta - Volume 361, Issue 4, 3 March 2008, Pages 1202–1206