Abstract
A new elastase secreted by Bacillus subtilis (natto) was purified and crystallized. The enzyme was purified by ammonium sulfate precipitation and repeated chromatography. The crystallization was performed in 60% saturated ammonium sulfate, and a rhombic crystal was obtained. The crystallized enzyme had a molecular mass of 29.8 kDa according to SDS-PAGE and an isoelectric point of 8.5. The optimum pH was 9.0, the optimum temperature was 50°C, and it was stable between pH 8.0 and 9.0. The elastin hydrolyzing activity of the enzyme was compared to the casein hydrolyzing activity, and the relative activity for elastin/casein value of the enzyme was higher than that of pronase. The elastase activity was inhibited by active-site inhibitors of serine protease, DFP and PMSF, and by inorganic metal ions. These characteristics show that the enzyme was different from the elastases previously reported.
