Enzyme modulator-ligand complexes - e.g. pepstatin-thyroxine ethyl ester complexes, and their use in enzyme mediated assay of ligands in body fluids

摘要

New enzyme modulator/ligand conjugates comprise an enzyme modulator component capable of irreversibly influencing and/or covalently binding the reference enzyme. New procedure for the determination of a ligand (esp. a biologically active cpd.) comprises (a) introducing into a liquid medium in a suitable order the (serum) specimen, the above enzyme modulator/ligand conjugate, a receptor which reacts under the influence of the enzyme modulator component, the reference enzyme and a substrate for the reference enzyme, (b) ccarrying out the reaction homogeneously or heterogeneously and (c) measuring the activity of the reference enzume. Measurement of substances such as pharmaceuticals, drugs, narcotics hormones, steroids, polypeptides, prostaglandins, toxins, etc. in body fluids such as blood or urine, e.g. in medical diagnosis. The use of enzyme modulator/ligand complexes in the determination is based on the finding that the irreversible effect of the enzyme modulator on the reference enzyme can be locked by the presence of receptors (esp. antibodies) for the ligand to which the enzymes modulator is bound. The new method is suitable for the determination of ligand concns. in the picomole range.