Biochemical and computational characterization of a recombinant catalase from Kocuria rhizophila for degradation of hydrogen peroxide in textile wastewater.

Catalase, an industrially important enzyme, catalyzes the hydrolysis of hydrogen peroxide into water and oxygen, playing a crucial role in various industries, including wastewater treatment in the textile sector. This study aimed to clone and express the catalase gene from Kocuria rhizophila ATCC 9341 into Escherichia coli BL21 (DE3), then characterize the purified enzyme and evaluate its potential for hydrogen peroxide degradation in textile wastewater. The 1524 bp gene was amplified and ligated into pET-21a( +) using the T4 DNA ligase enzyme. The expression of the recombinant catalase gene in E. coli BL21(DE3) was verified by using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis, with an estimated molecular weight of 57 kDa. The purified enzyme demonstrated a specific activity of 109.55 U/mg, optimal activity at pH 7-7.5, and 50 °C. The enzyme showed significant stability up to 80 °C and in a wide range of pH (4.0-9.0) by retaining up to 70% activity. The enzyme was also found to be resistant to several organic solvents, EDTA, β-mercaptoethanol, and metal ions, but was inhibited by Cu2+ and Cr2+. In-silico studies, including 3D modeling, quality validation, and molecular docking with hydrogen peroxide, confirmed strong ligand interactions, aligning with the experimental data. The combined experimental and computational findings suggest the enzyme's potential for industrial applications, especially in bioremediation and oxidative treatments.