Inhibition Assay: Using a 96 well plate (#3915, Costar), a test compound (25 μL) was mixed with 20 μM fluorescence enzyme substrate (Boc-Phe-Ser-Arg-AMC, 50 μL) mixed with 200 mM Tris-HCl buffer (pH 8.0), and human trypsin (Sigma, 25 μL) was added. Using a fluorescence plate reader fmax (Molecular Devices, Inc.), the reaction rate was measured from the time-course changes at excitation wavelength 355 nm and fluorescence wavelength 460 nm.
Inhibition Assay: Using a 96 well plate (#3915, Costar), a test compound (25 μL), 400 mM Tris-HCl buffer (pH 8.0, 25 μL) and 0.5 mg/mL fluorescence enzyme substrate (Gly-Asp-Asp-Asp-Asp-Lys-β-Naphtylamide, 25 μL) were mixed, and recombinant human enteropeptidase (R&D Systems, Inc., 25 μL) was added. Using a fluorescence plate reader fmax (Molecular Devices, Inc.), the reaction rate was measured from the time-course changes at excitation wavelength 320 nm and fluorescence wavelength 405 nm.
Enteropeptidase Inhibition Assay: Using a 96 well plate (#3915, Costar), a test compound (25 uL), 400 mM Tris-HCl buffer (pH 8.0, 25 uL) and 0.5 mg/mL, fluorescence enzyme substrate (Gly-Asp-Asp-Asp-Asp-Lys-beta-Naphtylamide, 25 uL) were mixed, and recombinant human enteropeptidase (R&D Systems, Inc., 25 uL) was added. Using a fluorescence plate reader fmax (Molecular Devices, Inc.), the reaction rate was measured from the time-course changes at excitation wavelength 320 nm and fluorescence wavelength 405 nm.
Trypsin Inhibition Assay: Using a 96 well plate (#3915, Costar), a test compound (25 uL) was mixed with 20 uM fluorescence enzyme substrate (Boc-Phe-Ser-Arg-AMC, 50 uL) mixed with 200 mM Tris-HCl buffer (pH 8.0), and human trypsin (Sigma, 25 uL) was added. Using a fluorescence plate reader fmax (Molecular Devices, Inc.), the reaction rate was measured from the time-course changes at excitation wavelength 355 nm and fluorescence wavelength 460 nm.