STABILITY OF ASSEMBLED EPITOPES ON HUMAN CHORIONIC-GONADOTROPIN TO COVALENT MODIFICATIONS - ANALYSIS USING MONOCLONAL-ANTIBODY PROBES

A measure of stability of a given epitope is an important parameter in the exploration of the utility of a desired MAb. It defines the condi tions necessary for using MAbs as an investigative tool in several res earch methodologies and therapeutic protocols. Despite these obvious i nterests the lack of simple and rapid assay systems for quantitating M Ab-Ag interactions has largely hampered these studies. A single step M Ab-Solid Phase Radioimmunoassay (SS-SPRIA), is described which elimina tes errors that may arise with multistep sandwich assays. SS-SPRIA has been used to demonstrate the differential stability of the assembled epitopes on gonadotropins. Differential stability towards specific rea gents can be exploited to identify aminoacid residues at the epitopic site. Inactivation of an epitopic region is indicative of the presence of the group modified, provided conformational relaxations are not in duced due to modifications at distant sites. Here we provide evidence to validate these conclusions.