Monoclonal antibodies to hog thyroglobulin recognizing disulfide-dependent conformational structures.

Monoclonal antibodies (MAbs) to hog thyroglobulin (Tg) were obtained by fusion of myeloma cells with B-lymphocytes from mice immunized with the protein. The five MAbs were classified into three groups which recognized different determinants; (1) MAb 4, (2) MAbs 6 and 10, and (3) MAbs 16 and 18. MAb 16 was IgG2b and the others IgG1. The immunoreactivity of Tg to the five MAbs was lost after reduction of the protein under denaturing conditions but remained after limited digestion by proteolytic enzymes. Tryptic fragments were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electrophoretically blotted and stained by a peroxidase-linked second antibody. Various sized tryptic fragments reacted similarly with the three MAbs which had different determinant specificities. All the MAb-reactable fragments in the tryptic digest completely lost their immunoreactivity after reduction of their disulfide linkages.