A highly stable manganese catalase from Geobacillus thermopakistaniensis: molecular cloning and characterization.

Catalases, heme or manganese, are efficient biocatalysts that split hydrogen peroxide into water and oxygen. We have cloned a manganese catalase from thermophilic bacterium, Geobacillus thermopakistaniensis, and expressed the corresponding gene in Escherichia coli. The gene product, CatGt, was synthesized in E. coli as inactive inclusion bodies. Solubilization and refolding of the inclusion bodies resulted in highly active CatGt with a specific activity of 18,521 μmol min-1 mg-1. The refolded protein exhibited apparent Km and kcat values of 260 mM and 10,360 s-1 subunit-1, respectively. It exhibited a half-life of 1 h at 100 °C. The unique features of CatGt are its high activity and thermostability. These features make it a valuable catalyst for industrial applications. To the best of our knowledge, CatGt is the most thermostable catalases characterized to date.