| abstract |
A homogeneous specific binding assay method and reagent means for determining a ligand, such as a hapten, antigen or antibody, in, or the ligand binding capacity of, a liquid medium employing a labeled conjugate which upon enzymatic cleavage produces a detectable indicator product. The improvement comprises employing as the label component in the labeled conjugate, a residue having the formula: P-X-M-R wherein P is a photophore, e.g., a fluorescer, which emits light upon exposure to excitation means, X is an enzymatically cleavable linkage, M is a modulator, e.g., a quencher, for said light emission of the photophore, and R is a linking group to the binding component, e.g., the ligand or analog thereof, in the labeled conjugate. The labeled conjugate and the cleaved indicator product emit substantially different amounts of light upon excitation due to modulation of the emission of photophore P by the proximity of modulator M in the labeled conjugate. |