title: Intracellular serine protease-4, a new intracellular serine protease activity from Bacillus subtilis.
abstract: A previously undiscovered intracellular serine protease activity, which we have called intracellular serine protease-4, was identified in extracts of stationary Bacillus subtilis cells, purified 260 fold from the cytoplasmic fraction, and characterized. The new protease was stable and active in the absence of Ca2+ ions and hydrolyzed azocasein and the chromogenic substrate carbobenzoxy-carbonyl-alanyl-alanyl-leucyl-p-nitroanilide, but not azocollagen or a variety of other chromogenic substrates. The protease was strongly inhibited by phenylmethylsulfonylfluoride, chymostatin and antipain, but not by chelators, sulfhydryl-reactive agents or trypsin inhibitors. Its activity was stimulated by Ca2+ ions and gramicidin S; its pH and temperature optima were 9.0 and 37 degrees C, respectively. Although intracellular serine protease-4 was immunochemically distinct from intracellular serine protease-1, it was absent from a mutant in which the gene encoding the latter was disrupted.
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana 61801.
authors.forename: S M
authors.initials: SM
authors.lastname: Sheehan
authors.forename: R L
authors.initials: RL
authors.lastname: Switzer
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D015151:Immunoblotting; D012697:Serine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology
chemical_list: D015842:Serine Proteinase Inhibitors; D012697:Serine Endopeptidases