CATL 18 |
| Soluble methane monooxygenase (sMMO), toluene/o-xylene monooxygenase (ToMO), phenol hydroxylase (PH), and related bacterial multicomponent monooxygenases convert C–H bonds selectively into C–OH bonds at ambient conditions. The alkane and alkene substrates of these enzymes are the sole source of carbon and energy for the organisms that consume them. The enzymes and bacteria are of interest in bioremediation as well as for industrial hydrocarbon functionalization applications. Studies of sMMO, ToMO, and PH have been performed to determine the structures of their hydroxylase, regulatory , and reductase protein components individually and in complex with one another. Dioxygen activation at carboxylate-bridged diiron(II) centers in the hydroxylase components is followed by hydrocarbon activation. In MMOH, this chemistry involves oxo-bridged diiron(IV) units, whereas the toluene and phenol hydroxylation steps in ToMOH and PHH, respectively, appear to occur at the diiron(III) level. One role of the regulatory components may be to protect the oxygenated intermediates from untimely reduction by the reductase proteins. We have employed this strategy to effect hydrocarbon oxidation by dioxygen under ambient conditions at synthetic carboxylate-bridged diiron units encapsulated in an appropriate sheath. The nature of an oxygenated intermediate in this chemistry has been investigated spectroscopically. This work was supported by the National Institute of General Medical Sciences. |
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Strategies in Enzymatic Oxidation Catalysis
8:30 AM-12:00 PM, Monday, August 20, 2007 BCEC -- 261, Oral
Catalysis & Surface Science Secretariat |