Proteases of the genus <i>Bacillus</i>. I. Neutral proteases

Abstract

Abstract B. subtilis NRRL B3411 neutral protease has been extensively purified by solvent, and salt fractional ion, pigment removal with DEAE‐cellulose followed by chromatography on hydroxylapatite, and a final passage through a Sephadex G‐100 column. The neutral protease was shown to be homogeneous by disc gel and cellulose acetate electrophoresis, gel filtration chromatography, and ultra‐centrifugation. The molecular weight was determined by osmometry and ultracentrifugation to be about 38–42,000 and the amino acid composition and zinc content determined. The general properties of the enzyme, pH‐activity relationship, stability, effect of inhibitors, and specificity are discussed. Comparative studies were carried out on the B. subtilis NRRL B3411 and B. subtilis var. amylosacchariticus neutral proteases and these enzymes were found to be indistinguishable by the methods used, but quite distinct from the thermostable enzyme thermolysin from B. thermoprotcolyticus .