Method for carrying out non-isotopic immunoassays, labeled analytes and kits for use in such assays

摘要

A highly sensitive, immunoassay method for determining the amount of an analyte in a sample containing a known analyte in an unknown concentration is provided. Sample; a polypeptide-labeled analog of the analyte, an antibody specific for said analyte, a polypeptide partner capable of non-covalently binding with the polypeptide-labeled analyte to form a complex having catalytic activity, and a substrate capable of being converted to a reporter molecule by the catalytic activity of said complex are brought together in a medium. The polypeptide-labeled analyte analog is capable of competitively binding to the antibody and the polypeptide partner, the antibody inhibiting the formation of a catalytically active complex in the absence of analyte, and the concentrations of the antibody, polypeptide partner and polypeptide-labeled analyte are such as to cause varying amounts of analyte to be directly related to the conversion of the substrate to the reporter molecule. Conversion of the substrate to the reporter molecule is then determined, and compared to conversions of substrate to reporter molecule obtained with known concentrations of the analyte.