| Assay Method Information | |
| | BACE Assay |
| Description: | For each compound being tested, the BACE activity was monitored in a fluorescence quenching assay (FRET) using the ectodomain of BACE (aa 1-454) fused to a myc-his tag and secreted from HEK293/BACEect. cells into OptiMEM (Invitrogen) as enzyme source and a substrate peptide derived from the APP-Swedish mutation which possesses a Cy3-fluorophore at the N-terminus and a Cy5Q-quencher at the C-terminus (Cy3-SEVNLDAEFK-Cy5Q-NH2; Amersham). The substrate was dissolved at 1 mg/mL in DMSO.The assay was performed in the presence of 5 μl OptiMEM (supernatant collected over 24 hours and cleared from cellular debris by centrifugation) containing the ectodomain of BACE, 25 μl water containing the desired concentration of test compound and 1% DMSO, 1 μM substrate peptide, 20 mM NaOAc, pH 4.4 and 0.04% Triton-X100 in a total assay volume of 50 μl in a 384 well plate. In general, 25 μl of compound dilution were given to the plate followed by the addition of 10 μl of BACE containing OptiMEM diluted 1:2 in water with 0.2% Triton X-100. The reaction was started with the addition of 15 μl substrate in NaOAc buffer. The reaction was incubated at 30° C. in a fluorimeter and the cleavage of the substrate was recorded as kinetic for 60 min. at ex: 530 nm, em: 590 nm. Blank wells containing either no inhibitor or no enzyme were included on each plate.The intensity of fluorescence was regressed against time in order to derive velocities of reaction in all 384 wells. These velocities were used for calculating percent inhibition using an uninhibited control containing 1% DMSO and a fully inhibited control incubations performed in the absence of enzyme. IC50 values were calculated by fitting percent inhibition vs. inhibitor concentration using standard software like GraphPadPrism. |
| Affinity data for this assay | |
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