MONOCLONAL-ANTIBODIES CAN REVEAL IMMUNOREACTIVITY DIFFERENCES BETWEENPITUITARY AND RECOMBINANT BOVINE GROWTH-HORMONE

Monoclonal antibodies (MAbs) to pituitary bovine growth hormone (bGH) were used to assay the immunoreactivity of a recombinant form of bGH. The recombinant hormone used differed from the pituitary principally i n the presence of a short amino acid sequence starting with methionine added to the N-terminal end of the molecule. Monoclonal antibody 1D2 recognized the recombinant hormone with greater affinity than the pitu itary hormone, whereas MAb 5G1 bound the recombinant molecule with a l ower strength than the pituitary. The other MAbs showed different beha vior depending on the type of immunoassay used. Results indicate that the recombinant bGH molecule has been altered in its immunological str ucture, and suggest a possible interaction of the added N-terninal fra gment with the three-dimensional structure of the hormone.