Biotransformation of N-Heterocyclic Compounds 1-Phenylpyrazole and 1-Phenylpyrrole by Escherichia coli (pDTG141) Expressing Naphthalene Dioxygenase of Pseudomonas sp. Strain NCIB 9816-4

Abstract

Naphthalene dioxygenase (NDO) from Pseudomonas sp. strain NCIB 9816-4 is a multicomponent enzyme system that carries out the initial step in the degradation of naphthalene. This enzyme has broad substrate range and catalyzes several types of reactions including cis-dihydroxylation, monooxygenation, and desaturation. 1-Phenylpyrazole and 1-phenylpyrrole were tested for biotransformation by NDO. High-performance liquid chromatography (HPLC) analysis showed two metabolites from each substrate. Liquid chromatography/ Mass Spectroscopy (LC/MS) analysis indicated the molecular weight of metabolites M1 and M2 of 1-phenylpyrazole were increased by 16 and 34, respectively, which could be produced from enzymatic monooxygenation and dioxgenation reactions. HPLC and LC/MS analyses of metabolites M3 and M4 from 1-phenylpyrrole showed increased molecular weights of 16 and 32, as compared to parent compounds, proposing addition of one and two atoms of oxygen to substrate, respectively Metabolite structures were confirmed by 1H- nuclear magnetic resonance (NMR) and 13C-NMR analyses. Metabolites M1 and M2 from 1-phenylpyrazole were determined as 1-phenyl-1Hpyrazol-4-ol and (1H-pyrazol-1-yl)cyclohexa-4′,6′-diene-cis-2′,3′-diol, respectively. Metabolite M3 from 1-phenylpyrrole was confirmed as (1H-pyrrol-1-yl)benzene-2′,3′-diol. NDO enzyme could be used to produce a novel synthon from N-heterocylic compounds, useful for synthesis of many biologically active compounds.