Purification and Properties of Neutral Protease from Bacillus Subtilis ZC-7 / 中国生物工程杂志

ABSTRACT

Bacillus subtilis ZC-7 was obtained by implantation with N+ ions beam to B.subtilis AS1.398,and compared with the AS1.398 neutral protease,the enzyme activity of ZC-7 neutral protease was about 1 timeshigher in previous research.A neutral protease was purified from the culture of B.Subtilis ZC-7 by the procedures including amoninium sulfate precipitation,ultrafiltration,DEAE-Sepharose Fast Flow chromatography and Sephadex G-75 chromatography.By multi-step purification,the ZC-7 neutral protease was purified to 78.5 folds and its yield was 27.7%,at last,the specific activity of ZC-7 neutral protease was up to 4.1?105U/mg.Analysed by SDS-PAGE,the purified protease has shown a molecular mass of about 42kDa.The Km for casein hydrolysis was 3.67?10-3?g/ml and the Vmax was 12.21?g/min.The optimum pH and temperature forhydrolysis of casein were 7.0 and 55℃,respectively.This protease was stable up to 40℃ within the pH range of 6.5 and 8.0.EDTA,isopropanol and alcohol nearly inhibited its activity while some ions such as Ca2+,Mg2+,Fe3+ can improve its activity.In addition,it could resist 1 mol/L H2O2.