Streptomyces subrutilus P5의 천연 Fe superoxide dismutase와 N-말단 6xHis-태그가 결합된 Fe superoxide dismutase의 활성비교

This study was carried out to analyze the differences in enzyme activity and stability between the native Fe superoxide dismutase (FeSOD) and the 6xHis-tagged superoxide dismutase (6xHis-FeSOD) of Streptomyces subrutilus P5. The optimum pHs for both native FeSOD and 6xHis-FeSOD were 7, while the pH range of the activity was narrower for the 6xHis-FeSOD. The native FeSOD was stable at pH 4–9, but the 6xHis-FeSOD lost its stability at pH > 9. The temperatures of the optimum activities were same for both types of enzymes. However, the heat stability of the 6xHis-FeSOD was clearly decreased; even at 20°C the enzyme lost the activity after 360 min. In contrast, the native FeSOD was stable after 720 min at below 40°C. H 2 O 2 inhibition was occurred already at 0.5 mM for the 6xHis-tagged enzyme. Therefore, from the results that the 6xHis-FeSOD retained the enzyme activity at pH 6–7 and 20–40°C, it can be assumed that the protein structure became destabilized under different storage conditions and sensitive to the enzyme inhibitor.