US Patent 7759072 Immunoassay method and reagent therefor

The present invention provides a novel immunoassay method with high reaction specificity and high sensitivity. The present invention also provides a method for immunoassaying a target antigen utilizing reactivation of an apoenzyme, which includes simultaneously or sequentially adding a test sample to an antibody specific to the target antigen, the target antigen labeled with a coenzyme, an apo-D-amino acid oxidase, a D-amino acid, and a reagent for detecting a hydrogen peroxide produced by the oxidase.