Fig. 2

CIEEL energy transfer requires close proximity of the energy source and the recipient fluorophore. a The absorption/emission spectra of Alexa Fluor 647 (red), and the chemiluminescence emission range of Galacton-plus (blue shaded region). b Each well contained equal amounts of biotinylated β-galactosidase for Galacton-plus activation. Increasing levels of streptavidin- or ovalbumin-conjugated Alexa Fluor 647 (0–160 pmol) were added into the wells. The total luminescence output of each well was first visualized without an emission filter (open). The plate was then imaged at 500 nm (self-decomposition) or 680 nm (CIEEL energy transfer). The levels of Alexa Fluor 647 were determined by a fluorescence imaging using an Ex 640/Em 680 nm filter set. c Quantitative representation of the CIEEL energy transfer at 680 nm. Error bar = SEM