Reactive oxygen species induce oxidative stress leading to cellular damage and a variety of human diseases. To remove these reactive oxygen species, cellular antioxidant system exists. Among them, extracellular superoxide dismutase (SOD3) is an antioxidant enzyme with excellent efficacy against asthma and excessive inflammatory reaction, and thus is expected as a strong biomedicine candidate substances. However, there are many difficulties in obtaining large amounts of active recombinant human SOD3 (hEC-SOD3).
Previous studies have shown that hEC-SOD3 is mostly composed of an inactive apo-enzyme when overexpressed in HEK293 cell and hEC-SOD3 rapidly lost its activity after purification, but the activity was maintained when metal ions, BSA (Bovine serum albumin) and PEG (Polyethylene glycol) was added. Furthermore, since the plasma half-life of hEC-SOD3 is as short as 1.54h, it is expected that the intact use of hEC-SOD as a medicine is limited.
Here, we prolonged half-life by fusing human serum albumin (HSA) to the N-term of hEC-SOD3. The expression level of HSA-conjugated SOD3 was higher than hEC-SOD3 in HEK293 cell and its anti-oxidative activity was similar to that of hEC-SOD3. In addition, the activity was maintained for over 14 days without addition of BSA or PEG, and the plasma half-life was extended to 13.3 hours. HSA-conjugated SOD3, developed through this study, may help overcome clinical barriers to drug development of hEC-SOD3 as a bio-drug.