Assay Method Information

Assay Name:  Biochemical FRET Based Assay
Description:  This assay is a Fluorescence Resonance Energy Transfer Assay (FRET) based assay. The substrate for this assay contains the Swedish Lys-Met/Asn-Leu mutation of the amyloid precursor protein (APP) beta-secretase cleavage site. This substrate also contains two fluorophores: (7-methoxycoumarin-4-yl) acetic acid (Mca) is a fluorescent donor with excitation wavelength at 320 nm and emission at 405 nm and 2,4-Dinitrophenyl (Dnp) is a proprietary quencher acceptor. The distance between those two groups has been selected so that upon light excitation, the donor fluorescence energy is significantly quenched by the acceptor, through resonance energy transfer. Upon cleavage by the beta-secretase, the fluorophore Mca is separated from the quenching group Dnp, restoring the full fluorescence yield of the donor. The increase in fluorescence is linearly related to the rate of proteolysis.Briefly in a 384-well format recombinant BACE2 protein in a final concentration of 0.4 μg/ml is incubated for 450 minutes at room temperature with 10 μM substrate in incubation buffer (50 mM Citrate buffer pH 5.0, 0.05% PEG, no DMSO) in the absence or presence of compound. Next the amount of proteolysis is directly measured by fluorescence measurement at T=0 and T=450 (excitation at 320 nm and emission at 405 nm). Results are expressed in RFU (Relative Fluorescence Units), as difference between T450 and TO.
Affinity data for this assay
 

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