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Updated: Oct 2, 2026

Qualitative and Quantitative Assays for Detection and Characterization of Protein Antimicrobials
Published on: April 10, 2016
Characterization of an inhibitor of the intracellular protease from Bacillus subtilis
Abstract:
A specific inhibitor of intracellular serylprotease from Bacillus subtilis has been isolated from both growing and sporulating cells. Like other protease inhibitors isolated from eukaryotic cells, the inhibitor from B. subtilis is a thermostable protein. A purification method is described. The molecular weight estimated by Biogel filtration and SDS gel electrophoresis is about 15,500. Both proteolytic and esterolytic activities of intracellular protease are equally sensitive to inhibition. With azocoll or Z-tyrosine p-nitrophenylester as substrates, noncompetitive inhibition patterns are observed. The inhibitor has no effect on the proteolytic or esterolytic activities of the extracellular serylprotease. A similar thermostable inhibitor is also present in Bacillus megaterium.
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