| Abstract: | A unique homogeneous enzyme immunoassay used for the determination of haptens and macromolecular antigens has been developed. It consists of avidin–antigen conjugate, anti-ligand antibody, and biotin enzyme (propionyl-CoA carboxylase). The immunological reaction of the conjugate with antibodies specific to ligand sterically prevents enzyme inactivation by avidin. Goat IgG and theophylline were used as model antigens. Avidin–theophylline conjugate inhibited 100% of enzyme activity. Avidin goat IgG conjugate inhibited 90% of enzyme activity. In this method, the measurable range of theophylline was from 500 ng/ml to 50 μg/ml, and for goat IgG, it was 1–1000 μg/ml. |
