Immunochemical Properties of Bovine and Human Pituitary-Growth Hormone After Pepsin Digestion1

Abstract

Human and bovine pituitary growth hormone (HGH and BGH) were digested with pepsin. The electrophoretic mobility and immunological properties, such as precipitation reactions in agar gel and hemagglutination with antiserum to the whole hormone, were studied at different degrees of digestion. It was found that enzymatic digestion splits both growth hormones into several electrophoretic components, most of which moved toward the cathode. One component of BGH (named f) moved toward the anode and showed a mobility similar to undigested HGH. Enzymatic digestion reduced the ability of both HGH and BGH to react with their respective antisera, but weak hemagglutination reactions were found even after 60 or 70% digestion. The individual electrophoretic components were eluted from the agar gel and tested against antisera to both HGH and BGH. Besides reacting with its homologous antiserum, component f of BGH gave a positive hemagglutination reaction with antiserum to HGH. This finding was interpreted as evidence that BGH possesses an immunologically identical core with HGH. (Endocrinology74: 532, 1964)