Studies on a new protease from a strain of Bacillus sphaericus. I. Purification and some properties of Bacillus sphaericus protease.

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A new protease, Sfericase, found in culture filtrate of a strain of Bacillus sphaericus was purified and isolated in a crystalline form by salting out with ammonium sulfate followed by column chromatography on DEAE-Sephadex A-50 (using a specific elution buffer). The optimal and maximal caseinolytic activities of the protease were around pH 9.0_??_9.3 and at 55°C, respectively. The proteolytic activity was inhibited by DFP, potato protease inhibitors and EDTA, but not by PCMB, o-phenanthroline, TPCK and TLCK. The molecular weight of the protease was estimated by sedimentation equilibrium (32, 000±400) and gel chromatography (27, 000). The enzyme molecule contained two atoms of undialyzable calcium ion and two halfcystine residues which should afford one disulfide linkage as no free sulfhydryl group was found even with the denatured enzyme. By immunological cross reaction, it was indicated that the enzyme was distinct from other alkaline proteases of Bacillus origins.
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