A murine monoclonal anti-metallothionein autoantibody recognizes a chemically synthesized amino-terminal heptapeptide common to various animal metallothioneins

Abstract

A murine hybridoma clone (MT 189-14-7) producing an IgM-class monoclonal antibody specific for metallothionein (MT) was produced with rat Zn-MT 2-keyhole limpet hemocyanin conjugate as an immunogen. The reactivity of the monoclonal antibody with MTs obtained from various animal species was determined by the competitive radioimmunoassay. The MT 189-14-7 antibody bound equally to various MTs 1 and 2 including mouse MTs 1 and 2. This indicates that the antibody is a murine autoantibody reactive with various animal MTs and recognizes a common structure of the various MTs. Subsequently, the location of the antigenic determinant recognized by the MT 189-14-7 antibody was determined by using various synthetic human MT 2 peptides. Among the synthetic peptides examined, both the amino-terminal beta-domain, Ac-(hMT 2 1-29)-OH, and an amino-terminal heptapeptide, Ac-(hMT 2 1-7)-OH, but not the carboxy-terminal alpha-domain peptides, H-(hMT 2 29-35)-OH and H-(hMT 2 30-61)-OH, showed inhibitory activities slightly higher than the native MTs in the competitive radioimmunoassay. These results demonstrate that the MT 189-14-7 autoantibody recognizes the epitope located within the amino-terminal heptapeptide common to various MTs.