The superoxide dismutase (TfSOD) gene from the extremely thermophilic bacterium Thermus filiformis was cloned and expressed at high levels in mesophilic host. The purified enzyme displayed approximately 25 kDa band in the SDS-PAGE, which was further confirmed as TfSOD by mass spectrometry. The TfSOD was characterized as a cambialistic enzyme once it had enzymatic activity with either manganese or iron as cofactor. TfSOD showed thermostability at 65, 70 and 80°C. The amount of enzyme required to inhibit 50% of pyrogallol autoxidation was 0·41, 0·56 and 13·73 mg at 65, 70 and 80°C, respectively. According to the circular dichroism (CD) spectra data, the secondary structure was progressively lost after increasing the temperature above 70°C. The 3-dimensional model of TfSOD with the predicted cofactor binding corroborated with functional and CD analysis.
Significance and impact of the study: This manuscript describes the expression and characterization of a superoxide dismutase (SOD) from Thermus filiformis with thermophilic and cambialistic characteristics. The SODs are among the most potent antioxidants known in nature, and their stability and pharmacokinetics can vary widely in accordance to their biological source. Although the currently clinical research work has been focused on human and bovine SODs, alternative sources may become more biotechnological attractive in the near future. Our study brings new insights for the research field of antioxidant enzymes with potential application on pharmaceutical, cosmetics and food formulations.
© 2013 The Society for Applied Microbiology.