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, Cat_Gt, was synthesized in E. coli as inactive inclusion bodies. Solubilization and refolding of the inclusion bodies resulted in highly active Cat_Gt with a specific activity of 18,521 μmol min^-1 mg^-1. The refolded protein exhibited apparent K_m and k_cat 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 Cat_Gt are its high activity and thermostability. These features make it a valuable catalyst for industrial applications. To the best of our knowledge, Cat_Gt is the most thermostable catalases characterized to date.