Enzyme Inhibition Assay: Enzyme activity is measured by observing the increase in fluorescence intensity caused by cleavage of a peptide substrate containing a fluorophore whose emission is quenched in the intact peptide.Assay buffer: 100 mM potassium phosphate pH 6.5, EDTA-Na 5 mM, Triton X-100 0.001%, DTT 5 mM.Enzymes (all at 1 nM): human and mouse Cathepsin S, Cat K, Cat B, Cat L.Substrate (20 μM): Z-Val-Val-Arg-AMC, except for Cat K which uses Z-Leu-Arg-AMC (both from Bachem).Z=Benzyloxycarbonyl.AMC=7-Amino-4-Methyl-Coumarin.DTT=dithiothreitol.Final volume: 100 μL.Excitation 360 nm, Emission 465 nm.Enzyme is added to the substance dilutions in 96-well microtitre plates and the reaction is started with substrate. Fluorescence emission is measured over 20 minutes, during which time a linear increase is observed in the absence of inhibitor.
Enzyme Inhibition Assay: Enzyme activity is measured by observing the increase in fluorescence intensity caused by cleavage of a peptide substrate containing a fluorophore whose emission is quenched in the intact peptide.Assay buffer: 100 mM potassium phosphate pH 6.5, EDTA-Na 5 mM, Triton X-100 0.001%, DTT 5 mM.Enzymes (all at 1 nM): human and mouse Cathepsin S, Cat K, Cat B, Cat L.Substrate (20 μM): Z-Val-Val-Arg-AMC, except for Cat K which uses Z-Leu-Arg-AMC (both from Bachem).Z=Benzyloxycarbonyl.AMC=7-Amino-4-Methyl-Coumarin.DTT=dithiothreitol.Final volume: 100 μL.Excitation 360 nm, Emission 465 nm.Enzyme is added to the substance dilutions in 96-well microtitre plates and the reaction is started with substrate. Fluorescence emission is measured over 20 minutes, during which time a linear increase is observed in the absence of inhibitor.