Apyrase immobilized on paramagnetic beads used to improve detection limits in bioluminometric ATP monitoring

A novel technique that is useful for the control of the luminescence output in a bioluminometric assay has been developed. The method relies on the immobilization on paramagnetic beads of an enzyme that is capable of catalysing the hydrolysis or oxidation of the substrate for the luminescence reaction. This technique has been used for control of the level of ATP in the luciferin-luciferase system. Biotinylated apyrase was bound to streptavidin coated paramagnetic beads and added to the assay mixture. The level of ATP in the reaction mixture was then conveniently controlled using an external magnet. The possible use of this approach in other systems, such as the bacterial luciferase-oxidoreductase is discussed.