Improved thermostability and catalytic efficiency of overexpressed catalase from B. pumilus ML 413 (KatX2) by introducing disulfide bond C286-C289

Catalase catalyzes the decomposition of hydrogen peroxide to water and oxygen. The main role of this enzyme is to prevent cell damage caused by reactive oxygen species (ROS). However, endogenous catalase is sensitive to high temperature and possesses limited activity. To satisfy requirements for this critical bottleneck, in this work, we improved the thermo-stability of a heme-catalase (KatX2) from a high oxidative stress resistance Bacillus pumilus ML413 through the construction of a disulfide bond between S286C and D289C. After the site-directed mutagenesis targeting the disulfide bond between S286C and D289C into the wild-type catalase, a potential improvement of thermo-stability half-life at 60 °C was increased by 48 min compared to the wild-type half-life. Unexpectedly, a catalytic efficiency of KatX2 S286C/D289C mutant was increased by 40% when compared to the wild-type KatX2. More importantly, this unprecedented highly stable KatX2 recombinant mutant S286C/D289C exhibits higher catalytic efficiency and thermo-stability with no change on the catalase secondary structure. Thus, this rational design based KatX2 could be adopted as a potential biocatalyst in industry.