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.
提供了一种高灵敏度的免疫分析方法,用于确定样品中含有未知浓度的已知分析物的数量。将样品,包括:分别标记有
多肽的分析物类似物、特异性
抗体、能够与分别标记有
多肽的分析物类似物非共价结合以形成具有催化活性的复合物的
多肽伴侣,以及能够通过该复合物的催化活性将底物转化为报告分子的底物,放置在介质中。分别标记有
多肽的分析物类似物能够竞争性地结合到
抗体和
多肽伴侣上,
抗体在没有分析物的情况下抑制催化活性复合物的形成,
抗体、
多肽伴侣和分别标记有
多肽的分析物的浓度使得分析物的不同浓度与底物转化为报告分子的量直接相关。然后确定底物转化为报告分子的转化率,并将其与已知分析物浓度下的底物转化为报告分子的转化率进行比较。