CHARACTERIZATION OF THE RESONANCE ENERGY-TRANSFER COUPLE COUMARIN-BODIPY AND ITS POSSIBLE APPLICATIONS IN PROTEIN-LIPID RESEARCH

In our search for suitable resonance energy transfer (RET) couples for studying protein-lipid interactions, the promising couple coumarin-BO DIPY was found and characterized. We characterized the RET from the do nor coumarin to two different dipyrrometheneboron difluoride (BODIPY)- labeled phospholipid analogs both experimentally and theoretically. Ca lculations using the spectral overlap revealed a Forster energy transf er radius (R(o)) of 50 +/- 2 Angstrom and 40 +/- 2 Angstrom for the co umarin-(beta-BODIPY FL C12-HPC) and the coumarin-(beta-BODIPY 530/550 C12-HPC) couple respectively. Experimentally this was estimated to be 49.0-51.5 Angstrom and 38.5-42.5 Angstrom respectively. The use of thi s couple for studying protein-lipid interactions is exemplified by mea surements on a bacterial precursor protein. (C) 1995 Academic Press, I nc.