PcpA is an enzyme used by Sphingobium chlorophenolicum to catalyze the oxidative cleavage of a halogenated aromatic substrate. The enzyme's ring cleaving mechanism, however, is not known. PcpA shows a high degree of substrate specificity, favoring 2,6-dihalogenated hydroquinones. Likewise, 2,6-dihalophenols act as PcpA inhibitors (Machonkin, et al., Biochemistry, 2011, 50, 8899�8913). To better understand this enzyme's substrate specificity, model complexes were prepared to mimic inhibitor-binding to the PcpA active site. The ligand tris(3,5-diphenylpyrazolyl)borate (TpPh2) was used to model the iron(II) binding site. The complexes (TpPh2)Fe(2,6-dibromophenolate) and (TpPh2)Fe(2,6-dichlorophenolate) were synthesized and characterized by single crystal X-ray crystallography and 1H-NMR. The presence of a halogen-metal secondary interaction was explored in these complexes.

Examination of the substrate specificity of the enzyme PcpA using synthetic model complexes

245th National Meeting (2013)

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