A thermostable superoxide dismutase from a thermophilic bacterium, called Geobacillus wiegeli (GWE1), isolated
from the interior of a sterilization drying oven, was purified by anion-exchange and molecular size-exclusion liquid
chromatography. On the basis of SDS-PAGE, the purified enzyme was found to be homogeneous and showed an estimated
subunit molecular mass of 23.9 kDa. The holoenzyme is a homotetramer of 97.3 kDa. Superoxide dismutase exhibited
maximal activity at pH 8.5 and at temperature around 60 ºC. The enzyme was thermostable maintaining 50% of its
activity even after 4.5 hours incubation at 60 ºC and more than 70% of its activity after 30 min at 80 ºC. When the microorganism
was irradiated with UVA, an increase in the specific activity of superoxide dismutase was observed which was
correlated with decreasing levels of anion superoxide, indicating the direct involvement of this enzyme in the capture of
reactive oxygen species. This study reports the effects of UV radiation on a superoxide dismutase from a thermophilic
bacterium isolated from an anthropogenic environment.
Keywords: Enzyme purification and characterization, sterilization oven’s microorganism, superoxide anion, superoxide dismutase,
thermophile, UV radiation.
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