Not so monofunctional—a case of thermostable Thermobifida fusca catalase with peroxidase activity
Thermobifida fusca is a mesothermophilic organism known for its ability to degrade plant biomass and other organics, and it was demonstrated that it represents a rich resource of genes encoding for potent enzymes for biocatalysis. The thermostable catalase from T. fusca has been cloned and overexpressed in Escherichia coli with a yield of 400 mg/L. Heat treatment of disrupted cells at 60 °C for 1 h resulted in enzyme preparation of high purity; hence, no chromatography steps are needed for large-scale production. Except for catalyzing the dismutation of hydrogen peroxide, TfuCat was also found to catalyze oxidations of phenolic compounds. The catalase activity was comparable to other described catalases while peroxidase activity was quite remarkable with a k obs of nearly 1000 s−1 for catechol. Site directed mutagenesis was used to alter the ratio of peroxidase/catalase activity. Resistance to inhibition by classic catalase inhibitors and an apparent melting temperature of 74 °C classifies this enzyme as a robust biocatalyst. As such, it could compete with other commercially available catalases while the relatively high peroxidase activity also offers new biocatalytic possibilities.
KeywordsThermobifida fusca Catalase Thermostable enzyme Peroxidase Oxidation
Nikola Lončar was supported by Serbian Ministry of Education, Science and Technological development through the project ON172048 and by International Center of Genetic Engineering and Biotechnology research grant CRP/YUG11-02.
Conflict of interest
The authors declare that they have no conflict of interest.
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