1. In vitro activation, purification, and characterization of Escherichia coli expressed aryl-alcohol oxidase, a unique H2O2-producing enzyme.
- Author
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Ruiz-Dueñas FJ, Ferreira P, Martínez MJ, and Martínez AT
- Subjects
- Emericella enzymology, Emericella genetics, Escherichia coli chemistry, Gene Expression Regulation, Enzymologic, Hydrogen-Ion Concentration, In Vitro Techniques, Inclusion Bodies enzymology, Inclusion Bodies metabolism, Pleurotus enzymology, Pleurotus genetics, Recombinant Proteins chemistry, Recombinant Proteins genetics, Recombinant Proteins isolation & purification, Time Factors, Alcohol Oxidoreductases chemistry, Alcohol Oxidoreductases genetics, Alcohol Oxidoreductases isolation & purification, Escherichia coli enzymology, Hydrogen Peroxide chemistry
- Abstract
Aryl-alcohol oxidase (AAO), a flavoenzyme with unique spectral and catalytic properties that provides H2O2 for fungal degradation of lignin, has been successfully activated in vitro after Escherichia coli expression. The recombinant AAO (AAO*) protein was recovered from inclusion bodies of E. coli W3110 transformed with pFLAG1 containing the aao cDNA from Pleurotus eryngii. Optimization of in vitro refolding yielded 75% active enzyme after incubation of AAO* protein (10 microg/ml) for 80 h (at 16 degrees C and pH 9) in the presence of glycerol (35%), urea (0.6 M), glutathione (GSSG/GSH molar ratio of 2), and FAD (0.08 mM). For large-scale production, the refolding volume was 15-fold reduced and over 45 mg of pure active AAO* was obtained per liter of E. coli culture after a single anion-exchange chromatographic step. Correct FAD binding and enzyme conformation were verified by UV-visible spectroscopy and circular dichroism. Although the three enzymes oxidized the same aromatic and aliphatic polyunsaturated primary alcohols, some differences in physicochemical properties, including lower pH and thermal stability, were observed when the activated enzyme was compared with fungal AAO from P. eryngii (wild enzyme) and Emericella nidulans (recombinant enzyme), which are probably related to the absence of glycosylation in the E. coli expressed AAO.
- Published
- 2006
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