Immunochemical detection of carboxymethylated Apo B-100 in copper-oxidized LDL

The objective of this study was to detect carboxymethyllysine (CML) moieties in biological materials using immunological methods. We prepared a polyclonal antibody specific to the carboxymethylated protein. The antibody recognizes the CML moiety in protein. Protein-bound carboxymethylcysteine (CMS) is scarcely recognized by the antibody. By use of the antibody, the formation of carboxymethylated apo B in copper-oxidized low density lipoprotein (ox-LDL) was immunochemically confirmed. To clarify the source compounds of carboxymethylation, various aldehyde-modified BSAs were prepared, and their reactivities with the antibody were investigated. Among the aldehyde-modified BSAs used, the glyoxal-BSA adduct showed a strong antigenicity. As far as we know, this is the first report of the detection of the CML moiety in ox-LDL using immunological methods.