INOR 757 |
| The active sites of metalloenzymes are often deeply buried inside a hydrophobic protein sheath, which protects them from undesirable hydrolysis and polymerization reactions, allowing them to achieve their normal functions. In order to mimic the hydrophobic environment of the active sites in bacterial monooxygenases, diiron(II) compounds of the general formula [Fe2([G-3]COO)4(R)2] were prepared, where [G-3]COO- is a third-generation dendrimer-appended terphenyl carboxylate ligand and R is a pyridine derivative. The dendrimer environment provides excellent protection for the diiron center, reducing its reactivity toward dioxygen by about 300-fold compared with analogous compound with terphenylcarboxylate ([G-1]COO-) ligands. An Fe(II)Fe(III) intermediate was characterized by electronic, EPR, and Mössbauer spectroscopic analysis following oxygenation of [Fe2([G-3]COO)4(4-PPy)2] (4-PPy = 4-pyrrolidinopyridine). The results suggested formation of a superoxo species. This intermediate can oxidize external substrates. Catalytic reactivity was observed with anthrone as the substrate. A catalytic oxidation mechanism describing this chemistry has been formulated and will be discussed. This work was supported by the National Institute of General Medical Sciences (to SJL) and the National Science Foundation (DMR to JMJF). |
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Bioinorganic Chemistry: Enzymes and Coenzymes
7:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Inorganic Chemistry |