The preparation of a human chorionic gonadotropin specific immunoadsorbent using human chorionic gonadotropin beta carboxyl terminal peptide antibody and its application to isolate human chorionic gonadotropin like substances from human pituitary glands
Matsuura, S.; Takeuchi, Y.; Mochizuki, M.
Folia Endocrinologica Japonica 60(6): 800-813
It has been difficult to distinguish hCG [chorionic gonadotropin] from hLH [luteinizing hormone] because the 2 are structurally similar. However, hCG.beta. subunit has a unique carboxyl terminal peptide, which is not present in hLH and other goandotropins. Taking advantage of this unique structural feature of hCG.beta. subunit, hCG-specific antisera were produced. To isolate hCG-like substances from human pituitary glands, the specific immunoadsorbent for hCG was prepared using the isolated monospecific antibody from these antisera.Specific IgG fraction was isolated from an antiserum by affinity chromatography using synthetic carboxyl-terminal peptides as ligands. The purified IgG was conjugated to Sepharose 4B to prepare a specific immunoadsorbent. Immunoadsorbent thus prepared was sully specific to hCG without any crossreactivity with hLH. Attempts to isolate hCG-like substances from 2 different human pituitary extracts were made by affinity chromatography using this hCG-specific immunoadsorbent. Elution conditions for hCG-like substances from the immunoadsorbent were studied. It was found that 1 M NH4OH was a highly effective eluent in this affinity chromatographic system. An advantage of 1 M NH4OH is its volatile nature, which permits further steps of purification to be performed directly or after lyophilization without extensive dialysis. The immunoaffinity procedures described may provide a convenient approach to purify hCG-like substances from both endocrine glands and biological fluids.