Quenching of biotinylated aequorin bioluminescence by dye-labeled avidin conjugates: application to homogeneous bioluminescence resonance energy transfer assays.

[see reaction]. Avidin conjugates containing the covalently attached dyes QSY-7 and dabcyl were prepared and shown to quench the bioluminescence of biotinylated aequorin. Quenching efficiency was shown to be dependent on both the label-to-avidin ratio and the concentration of the avidin conjugate. These properties were exploited to develop a homogeneous bioluminescence resonance energy transfer (BRET) assay for biotin.