فهرست نشریات علمی دسترسی آزاد ایران

Introduction: Catalase is a widely used enzyme with numerous advantages in industrial, diagnostic, and therapeutic applications. This study elucidates the characteristics of recombinant catalase hydroperoxidase II (rHPIISeq) from Staphylococcus equorum.Materials and Methods: A synthetic gene of catalase (hpII) was expressed in Escherichia coli BL21(DE3). The gene was codon-optimized and cloned commercially into vector pET-15b. Gene expression was performed under 0.5 mM of isopropyl-β-D-1-thiogalactopyranoside (IPTG) induction for 24 hours at 25 °C. The soluble recombinant catalase, rHPIISeq, was partially purified using ammonium sulfate precipitation followed by dialysis. Its activity was measured at 440 nm using a UV-visible spectrophotometer. Additionally, the effects of pH and temperature on the enzyme activity and stability were evaluated by incubating the enzyme across various pH levels and temperatures.Results: The pET-15b_HPIISeq recombinant plasmid was successfully constructed. The optimized gene of hpII consisted of 1,989 bp and encoded the rHPIISeq protein with a size of 75.22 kDa. The yield of soluble rHPIISeq was 9.73 mg in 1 L culture with 1.5–1.6 g of wet weight bacterial mass. Notably, approximately 90% of the produced protein formed inclusion bodies (IBs). Following partial purification, a 7-fold increase in the purification of soluble rHPIISeq was achieved using 40% ammonium sulfate precipitation, resulting in a purity level of about 60% with a yield of 93.7%. The enzyme exhibits optimal activity at a pH of 7 and a temperature of 40 °C, and it remains stable within a pH range of 6 to 10 at temperatures between 20 °C and 50 °C.Conclusions: This recombinant catalase is proposed as a mesophilic-alkali-stable enzyme, which is potentially beneficial for industrial applications, particularly in processes under alkaline conditions and a wide range of temperatures.