An efficient method to eliminate the protease activity contaminating commercial bovine pancreatic DNase I

A method was developed to eliminate the proteases contaminating commercial DNase I, which can cause degradation of target protein during the purification process. Bio Basic DNase stock solution (in Tris–HCl buffer pH 8.0] containing 5 mM CaCl₂) was first incubated at 50 °C to generate autolysis of proteases and zymogens, leading to a significant reduction in protease activity while preserving DNase activity. The residual protease activity was completely inhibited by further incubation with 2 mM PMSF (phenylmethylsulfonyl fluoride) or 2× S8830 inhibitor cocktail. This approach could be readily applicable to eliminate the protease activity in any DNase products or during the preparation of commercial DNase.