Abstract:[Objective] This study aims to design a fusion protein with high activities and high stability of superoxide dismutase (SOD) and catalase (CAT).[Method] Using AcSOD11 and FeCAT proteins as the research subjects, three fusion proteins of SOD and CAT were designed: AcSOD11-(GGGGS)*3-FeCAT, FeCAT-(GGGGS)*3-AcSOD11, and FeCAT-(EAAAK)*3-AcSOD11, which were named AcSOD11-G3-FeCAT, FeCAT-G3-AcSOD11, and FeCAT-E3-AcSOD11, respectively. Soluble expression of these three fusion proteins was achieved in Escherichia coli BL21(DE3). The thermal stability and pH stability of the three fusion proteins were then assessed.[Result] The three fusion proteins showed no significant difference in the specific activity of SOD, while they had significant differences in the specific activity of CAT. The specific activity of CAT was the highest (531 U/mg) in FeCAT-G3-AcSOD11 and the lowest in FeCAT-E3-AcSOD11, indicating that the flexible (GGGGS)*3 peptide linker was favorable for maintaining CAT enzyme activity. Stress resistance studies demonstrated that both CAT and SOD in FeCAT-G3-AcSOD11 exhibited strong tolerance to high temperatures and varying pH conditions.[Conclusion] This study successfully constructed three fusion proteins and obtained FeCAT-G3-AcSOD11, a highly stable fusion protein with high enzyme activities of both SOD and CAT, providing a theoretical foundation for the combined application of SOD and CAT.
