Aromatic hydroxylation catalyzed by toluene 4-monooxygenase in organic solvent/aqueous buffer mixtures

S. F. Oppenheim, J. M. Studts, B. G. Fox, J. S. Dordick

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17 Scopus citations


Toluene 4-monooxygenase is a four-protein component diiron enzyme complex. The enzyme catalyzes the hydroxylation of toluene to give p-cresol with ∼96% regioselectivity. The performance of the enzyme in two-phase reaction systems consisting of toluene, hexane, or perfluorohexane and an aqueous buffer was tested. In each of the cosolvent systems, containing up to 93% (v/v) of solvent, the enzyme was active and exhibited regioselectivity indistinguishable from the aqueous reaction. Using the perfluorohexane/buffer system, a number of polycyclic aromatic hydrocarbons were oxidized that were not readily oxidized in aqueous buffer. An instability of the hydroxylase component and a substantial uncoupling of NADH utilization and product formation were observed in reactions that were continued for longer than ∼3 min. More stable enzyme complexes will be needed for broad applicability of this hydroxylating system in nonaqueous media.

Original languageEnglish
Pages (from-to)187-197
Number of pages11
JournalApplied Biochemistry and Biotechnology
Issue number3
StatePublished - 2001
Externally publishedYes


  • Diiron enzyme
  • Monooxygenase
  • Organic cosolvents
  • Regioselective hydroxylation


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