Materials and Reagents

1. Hydroquinone dioxygenase from an Escherichia coli (E. coli) strain heterologously overexpressing such an enzyme from a plasmid (Mancini et al., 2015)
   
2. Hydroquinone (100 mM in ethanol) (Sigma-Aldrich, catalog number: H9003 )
   
3. 50 mM Tris-Cl [pH 7.5, 10% (v/v) glycerol]
   
4. 20 mM Tris-Cl (pH 7.5)
   
5. 10 mg/ml DNaseI (Sigma-Aldrich, catalog number: 11284932001 )
   
6. 10 mM isopropyl-b-D-thiogalactoside (Sigma-Aldrich, catalog number: I6758 )
   
7. 100 mM 4-hydroxybenzoate (Sigma-Aldrich, catalog number: H5501 )
   
8. 100 mM phenylmethylsulfonyl fluoride (Sigma-Aldrich, catalog number: P7626 )
   
9. 1 mM phenylmethylsulfonyl fluoride (Roche Diagnostics)
   
10. Nitrocellulose filters (0.45 μm pore size)
    
11. 100 mM hydroquinone (see Recipes)
    
12. 50 mM Tris-Cl (see Recipes)
    
13. 20 mM Tris-Cl (see Recipes)
    
14. 10 mg/ml DNaseI (see Recipes)
    
15. 10 mM isopropyl-β-D-thiogalactoside (see Recipes)
    
16. 100 mM 4-hydroxybenzoate (see Recipes)
    
17. 100 mM phenylmethylsulfonyl fluoride (see Recipes)
    

Equipment

1. Thermostated spectrophotometer (Shimadzu, model: UV2600 or similar)
   
2. Clark electrode (Warner Instruments, model: 1302 or any other commercial oxygraph)
   
3. French Press
   

Procedure