Applied Biochemistry and Biotechnology

, Volume 90, Issue 3, pp 187–197 | Cite as

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

  • Sheldon F. Oppenheim
  • Joey M. Studts
  • Brian G. Fox
  • Jonathan S. Dordick
Article

Abstract

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.

Index Entries

Diiron enzyme monooxygenase organic cosolvents regioselective hydroxylation 

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Copyright information

© Humana Press Inc. 2001

Authors and Affiliations

  • Sheldon F. Oppenheim
    • 1
  • Joey M. Studts
    • 2
  • Brian G. Fox
    • 2
  • Jonathan S. Dordick
    • 1
  1. 1.Department of Chemical EngineeringRensselaer Polytechnic InstituteTroy
  2. 2.Department of Biochemistry, College of Agricultural and Life SciencesUniversity of WisconsinMadison

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