Human and porcine thyrotropins: A comparison of electrophoretic and immunological properties with the bovine hormone

Abstract

The electrophoretic and immunochemical properties of purified human and porcine thyrotropins (TSH) have been compared with those of the bovine hormone. Preparations from all three species show similar polymorphism in gel electrophoresis. Human TSH exhibits more electronegative character than either porcine or bovine TSH due to the presence of about 1.5% sialic acid whereas the bovine and porcine material are essentially free of sialic acid. Removal of the sialic acid by neuraminidase does not affect the hormonal activity or immunochemical properties of human TSH. Immunological cross reactivity was found in double diffusion between the TSH of all three species with antisera to any of the three. Anti-human TSH serum completely neutralized the biological activity of the bovine and porcine hormones. These studies also demonstrated the bovine and porcine hormones to be quite similar, a conclusion further supported by peptide maps. In addition, human TSH appears to be closely related immunologically to denatured bovine TSH when the two are compared against anti-bovine TSH serum. The separation of the closely related glycoprotein, luteinizing hormone (LH), from TSH has been studied by biological and immunochemical criteria. Rechromabovine tography of TSH on diethylaminoethyl cellulose yielded preparations whose LH content as assayed by depletion of ovarian ascorbic acid was about 2% by weight. Absorption by an anti-LH serum further reduced the LH activity to values representing less than 1% contamination by weight. Examination of immunodiffusion properties of LH and TSH with antisera to each hormone yielded no evidence of cross reactivity between either bovine or human TSH and the homologous luteinizing hormones.