Intramolecularly quenched fluorescent substrate containing the ortho-aminobenzoyl (Abz) / N-(2,4-dinitrophenyl)ethylenediamine (EDDnp) groups as the donor / acceptor pair. It corresponds to the Swedish-mutated (JMV2236) β-amyloid precursor protein (βAPP) sequence targeted by β-secretase BACE (β-site APP-cleaving activity). This FRET substrate is more selectively cleaved by BACE1 and BACE2 than by cathepsin D, a disintegrin and metalloprotease 10 (ADAM10), tumor necrosis α-converting enzyme (TACE), presenilin-1 (PS1), or presenilin-2 (PS2).