Isolation and properties of porcine thyrotropin-releasing hormone.

Isolation on a preparative scale of thyrotropin-releasing rormone from porcine hypothalami is described. The yields ‘ram two batches of 100,000 and 165,000 hypothalami were !.8 mg and 4.4 mg, respectively. The material with thyro:ropin-releasing hormone activity, calculated to be purified Ibout 570,000 times, was active in mice at doses of 1 ng in jiuo, and stimulated the secretion of thyroid-stimulating rormone from rat pituitaries in vitro at doses of 10 pg. Thin ayer chromatography, electrophoresis, and paper chromatog‘aphy indicated that the material was homogeneous. Histiline, glutamic acid, and proline, which were present in an :quimolar ratio, accounted for about 32% of the dry weight )f the active material. However, eight synthetic peptides :ontaining histidine, proline, and glutamic acid or glutamine lad no thyrotropin-releasing hormone activity at doses as arge at 10 pg. Biological activity of thyrotropin-releasing lormone was abolished by diazotized sulfanilic acid, Nnomosuccinimide, or acid hydrolysis, but was not affected )y periodate or by incubation with proteolytic enzymes.