title: Allosteric control of βII-tryptase by a redox active disulfide bond.
abstract: The S1A serine proteases function in many key biological processes such as development, immunity, and blood coagulation. S1A proteases contain a highly conserved disulfide bond (Cys(191)-Cys(220) in chymotrypsin numbering) that links two β-loop structures that define the rim of the active site pocket. Mast cell βII-tryptase is a S1A protease that is associated with pathological inflammation. In this study, we have found that the conserved disulfide bond (Cys(220)-Cys(248) in βII-tryptase) exists in oxidized and reduced states in the enzyme stored and secreted by mast cells. The disulfide bond has a standard redox potential of -301 mV and is stoichiometrically reduced by the inflammatory mediator, thioredoxin, with a rate constant of 350 m(-1) s(-1). The oxidized and reduced enzymes have different substrate specificity and catalytic efficiency for hydrolysis of both small and macromolecular substrates. These observations indicate that βII-tryptase activity is post-translationally regulated by an allosteric disulfide bond. It is likely that other S1A serine proteases are similarly regulated.
authors.affiliation: From the Lowy Cancer Research Centre and Prince of Wales Clinical School and.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Cook
authors.forename: H Patrick
authors.initials: HP
authors.lastname: McNeil
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Hogg
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D045744:Cell Line, Tumor; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008407:Mast Cells / Q000201:enzymology* / Q000378:metabolism; D051379:Mice; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D053802:Tryptases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004220:Disulfides; D053802:Tryptases; D003545:Cysteine
keywords: Allosteric Regulation; Disulfide; Mast Cell; Redox Regulation; Serine Protease