Purification and Characterization of a Thermostable Serine Protease from Bacillus thuringiensis(Biological Chemistry)

概要

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Bacillus thuringiensis var. kurstaki HD-255 was found to produce an extracellular, thermostable protease after the end of the vegetative growth phase. The purified enzyme had a molecular weight of 34,000 according to sodium dodecyl sulfate-polyacry lamide gel electrophoresis and an isoelectric point of 9.0. Its proteolytic activity was inhibited by an active-site inhibitor of serine protease, phenylmethylsulfonyl fluoride, and also by an SH-modifying reagent, p-chloromercuribenzoic acid, suggesting that the enzyme is one of a subfamily of SH-containing serine proteases. The enzyme showed maximal proteolytic activity at 70℃ and pH 8.5〜9. The most interesting characteristic was its thermostability ; it retained 88.4% of its initial activity at pH 8.7 and 60℃ after more than 7hr incubation in the presence of 2mM CaCl_2.
社団法人日本農芸化学会の論文
1989-12-23