The bis-pyrenyl phospholipase substrate, 1,2-bis-(1-pyrenedecanoyl)-sn-glycero-3-phosphocholine emits at ~470 nm, indicating that the adjacent pyrene fluorohopres are forming excited-state dimers. Phospholipase A-mediated hydrolysis separates the fluorophores, which then emit as monomers at ~380 nm. This can be used as a substrate for either phospholipase A1 or A2.