CHEMBL3707535

HTRF FRET Assay: Inhibitor IC50s at purified human autoBACE-2 were determined in a time-resolved endpoint proteolysis assay that measures hydrolysis of the QSY7-EISEVNLDAEFC-Eu-amide FRET peptide substrate (BACE-HTRF assay). BACE-mediated hydrolysis of this peptide results in an increase in relative fluorescence (RFU) at 620 nm after excitation with 320 nm light. Inhibitor compounds, prepared at 3x the desired final concentration in 1xBACE assay buffer (20 mM sodium acetate pH 5.0, 10% glycerol, 0.1% Brij-35) supplemented with 7.5% DMSO were pre-incubated with an equal volume of autoBACE-2 enzyme diluted in 1xBACE assay buffer (final enzyme concentration 1 nM) in black 384-well NUNC plates for 30 minutes at 30 C. The assay was initiated by addition of an equal volume of the QSY7-EISEVNLDAEFC-Eu-amide substrate (200 nM final concentration, Km=8 M for 4 M for autoBACE-2) prepared in 1xBACE assay buffer supplemented with 7.5% DMSO and incubated for 90 minutes at 30 C.