Studies on Bacterial Protease

A neutral protease of Bacillus subtilis var. amylosacchariticus was purified and crystallized by sequential chromatography on columns of Duolite A-2 anion-exchange resin, CM-cellulose and DEAE-sephadex A-50. The crystalline preparation was chromatographically homogeneous and confirmed to be monodispersive by physicochemical criteria. The enzyme was most active at near pH 7 against casein and stabilized by calcium salts. Some metalchelating agents and metal ions such as Hg?, Pb?, Cu? and Fe? markedly inactivated the enzyme, whereas diisopropyl phosphorofluoridate, sulfhydryl reagents and protease inhibitor of potato did not affect the activity. The neutral protease obtained here was rather stable as compared with the neutral protease ever reported and was able to be freeze-dried without any appreciable lose in enzyme activity.