Abstract: Systems, including compositions, kits, and methods, particularly for photoluminescence applications. The systems may include, among others, (1) organic chelators, (2) complexes between the chelators and lanthanide ions, and (3) precursors, derivatives, and uses thereof. The chelators may include a 1,4,7,10-tetraazacyclododecane ring system, for example, having the formula: Here, R1, R2, and R3 are substituents of the tetraazacyclododecane ring system, that is further substituted at the 10-position by a sensitizer Z that is typically a polyheterocyclic ring system. The organic chelator may be capable of forming a luminescent complex with a lanthanide ion, and is optionally further substituted by a reactive functional group or a conjugated substance. The resulting lanthanide complex may be useful in luminescence-based assays, such as energy transfer assays, among others.

Abstract: Systems for detecting molecular modifications and the presence and/or activity of enzymes and/or other agents involved in facilitating or otherwise regulating such modifications.

Abstract: Assays for detecting molecular modifications, such as phosphorylation, dephosphorylation, and/or cleavage, among others, of lipids, lipid fragments, and/or lipid precursors. These assays may be used to detect the presence and/or activity of enzymes and/or other agents, such as drugs, involved in facilitating, inhibiting, and/or otherwise regulating such modifications.

Abstract: Assays for detecting the presence and activity of cell-signaling components. These assays include luminescence polarization assays for detecting cell-signaling nucleotides and modulators of receptors and enzymes related to the generation and activity of such nucleotides.