Original
Purification and characterization of hydroquinone dioxygenase from Sphingomonas sp. strain TTNP3
1 Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Muttenz, Switzerland
2 Institute for Environmental Research, Rheinisch-Westfälische Technische Hochschule, Aachen, Germany
3 Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
4 Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
5 Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
6 Centre for Applied Genomics, Prague, Czech Republic
7 Institute of Clinical Chemistry and Laboratory Medicine, University of Rostock, Rostock, Germany
8 Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
9 School of the Environment, Nanjing University, Nanjing, China
AMB Express 2011, 1:8 doi:10.1186/2191-0855-1-8
Published: 27 May 2011Abstract
Hydroquinone-1,2-dioxygenase, an enzyme involved in the degradation of alkylphenols in Sphingomonas sp. strain TTNP3 was purified to apparent homogeneity. The extradiol dioxygenase catalyzed the ring fission of hydroquinone to 4-hydroxymuconic semialdehyde and the degradation of chlorinated and several alkylated hydroquinones. The activity of 1 mg of the purified enzyme with unsubstituted hydroquinone was 6.1 μmol per minute, the apparent Km 2.2 μM. ICP-MS analysis revealed an iron content of 1.4 moles per mole enzyme. The enzyme lost activity upon exposure to oxygen, but could be reactivated by Fe(II) in presence of ascorbate. SDS-PAGE analysis of the purified enzyme yielded two bands of an apparent size of 38 kDa and 19 kDa, respectively. Data from MALDI-TOF analyses of peptides of the respective bands matched with the deduced amino acid sequences of two neighboring open reading frames found in genomic DNA of Sphingomonas sp strain TTNP3. The deduced amino acid sequences showed 62% and 47% identity to the large and small subunit of hydroquinone dioxygenase from Pseudomonas fluorescens strain ACB, respectively. This heterotetrameric enzyme is the first of its kind found in a strain of the genus Sphingomonas sensu latu.
