Enhanced Thermo-Stability and Catalytic Efficiency of Catalase by Site-Directed Mutagenesis

Abstract:

Catalase catalyzes the breakdown of hydrogen peroxide to form water and oxygen. The main role of this enzyme is to protect cell damage against reactive oxygen species（ROS）. Although it is widely used industrially，it is sensitive to high temperature，which limits its use. In this work，a thermo-stable heme-catalase（KatX2） was constructed with high catalytic efficiency from Bacillus pumilus ML413 through site-directed mutagenesis and using PoPMuSiC algorithm to predict and calculate folding free energy of highly potential residues for mutation. Lys117 was selected and genetically engineered to enhance KatX2 thermostability. From the set of mutants，the K117V recombinant mutant showed significant improvement in thermo-stability with the increase of half-life at 60 ℃ by 38 minutes compared to the wild-type. Furthermore，the catalytic efficiency of K117V mutant was increased by 31.7% compared to that of the wild-type. Interestingly，no change of secondary structure was observed after structural analysis. Therefore，this highly stable KatX2 could be used as a potential industrial biocatalyst.