Method for assaying receptor binding property and reagent for the assay

Abstract

The present invention provides a method capable of simultaneous processing of plural test samples for the receptor binding property of a chemical substance, which does not require imobilization of the receptor or a special device, and a reagent to be used for this method. That is a method for assaying the receptor binding property of an assay target substance is provided, the method comprising the steps of (a) competitively reacting a known concentration of a ligand and the assay target substance with a known concentration of the receptor in a solution, (b) measuring, without physically removing the ligand bound with the receptor prior to the assay, the amount of a free ligand in the solution using one or more antibodies against the ligand, and (c) determining the receptor binding property of the assay target substance using the amount of the free ligand as an index.

What is claimed is:  
     
         1 . A method for assaying the receptor binding property of an, assay target substance, comprising the steps of 
 (a) competitively reacting a known concentration of a ligand and the assay target substance with a known concentration of the receptor in a solution,    (b) measuring, without physically removing the ligand bound with the receptor prior to the assay, the amount of a free ligand in the solution using one or more antibodies against the ligand, and    (c) determining the receptor binding property of the assay target substance using the amount of the free ligand as an index.    
     
     
         2 . The method of  claim 1 , wherein the step (b) comprises adding one or more antibodies against the ligand and a labeled ligand to the reaction mixture obtained in step (a) to allow competitive reaction of the antibody and the free or labeled ligand, and measuring the amount of the label bound or not bound with the antibody.  
     
     
         3 . The method of  claim 1 , wherein the antibody retains its activity by 60% or more in a 1% organic solvent.  
     
     
         4 . The method of  claim 1 , wherein the ligand is not labeled, bound, processed or denatured.  
     
     
         5 . The method of  claim 1 , wherein the receptor is used in an amount that produces binding of 50% or more of the ligand with the receptor.  
     
     
         6 . The method of  claim 1 , wherein the receptor is selected from the group consisting of receptors of hormone, drug, drug metabolite, polypeptide, protein, saccharides, biochemical messenger and vitamin and ligand binding domains thereof.  
     
     
         7 . A reagent for assaying the receptor binding property of a substance, comprising a reagent containing a known concentration of a receptor, a reagent containing a known concentration of a ligand of a known concentration of the receptor, and a reagent for measuring a free ligand, which contains one or more antibodies against the ligand.  
     
     
         8 . The reagent of  claim 7 , further comprising a reagent containing the ligand which has been labeled.  
     
     
         9 . The reagent of  claim 7 , wherein the antibody retains its activity by 60% or more in a 1% organic solvent.  
     
     
         10 . The reagent of  claim 7 , wherein the ligand is not labeled, bound, processed or denatured.  
     
     
         11 . The reagent of  claim 7 , wherein the receptor is used in an amount that produces binding of 50% or more of the ligand with the receptor.  
     
     
         12 . The reagent of  claim 7 , wherein the receptor is selected from the group consisting of receptors of hormone, drug, drug metabolite, polypeptide, protein, saccharides, biochemical messenger and vitamin and ligand binding domains thereof.