BIOL 223 |
| The intradiol catechol dioxygenases are a family of non-heme iron-dependent enzymes that catalyse the oxidative cleavage of catechol substrates, containing a mononuclear iron (III) cofactor. The aim of this project is to study three possible mechanisms for hydroperoxide rearrangement of intradiol dioxygenase enzyme CatA, shown below. Three mechanistic probes (meta-chloroperbenzoic acid (1), spiroepoxy-cyclohexadienone (2) and 2-hydroperoxy-2-methylcyclohexanone (3)) were designed and prepared. Incubation reactions were carried out with the probes and purified CatA, and the products were analysed by HPLC and GC-MS. Incubation of MCPBA with CatA led to formation of 2- and 3- chlorophenol, consistent with O-O homolysis pathway. Treatment of MCPBA with purified extradiol dioxygenase MhpB from E. coli DH5α/pIPB also generated the same products in a different ratio. Incubation of probe 2 with extradiol dioxygenase MhpB forms 2-tropolone, via ring expansion, consistent with 1,2-alkenyl migration in the extradiol dioxygenase mechanism.
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Frontiers in Chemical Biology
5:00 PM-7:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Biological Chemistry |
