Heterogenous specific binding assay employing a cycling reactant as label

Abstract

An improved heterogenous specific binding assay method which employs a substance having reactant activity, i.e., a reactant, as a labeling substance in the detection of a ligand in a liquid medium. The method is carried out using reagent means which comprises, as its labeled constituent, a conjugate formed of a specific binding substance coupled to the reactant. The reactant advantageously is an enzymatic reactant such as an enzyme substrate or coenzyme. The activity of the conjugated reactant as a constituent of a predetermined reaction system is utilized as means for monitoring the extent of binding of the labeled constituent in conventional heterogenous specific binding assay schemes. The presence of a ligand in a liquid medium may be determined following conventional competitive binding manipulative techniques. After the necessary separation of the bound-and free-phases resulting in the specific binding reaction system, the extent of binding of the labeled constituent is determined by contacting either phase with the necessary materials to form the predetermined monitoring reaction system in which the labeling substance is active and assessing reactant activity therein.

Dependencies are inferred from the claim text.