Chapter 19. Peptide Hormones

Publisher Summary This chapter describes the advances in the development of peptide hormones. Abundant evidence has been accumulated that the secretion of the neurohypophyseal hormones is under the control of substances produced in the hypothalamus. These substances, releasing or inhibiting factors, travel to the anterior pituitary by means of the pituitary portal circulation, and there cause (or inhibit) the degranulation of specific cell types which contain the tropic hormones. Human placental lactogen, renamed “human chorionic somato-mauxnotropin,” had anabolic effects when administered to hypopituitary dwarfs in large doses. Thyroid-stimulating hormone (TSH), a glycoprotein of molecular weight about 25,000 has been purified from bovine, porcine, and human pituitaries. The human and bovine hormones have a common C-terminal pentapeptide sequence, His-Tyr-Lys-Ser-Tyr, while the porcine hormone lacks the C-terminal tyrosine. The human hormone may be two different molecules having a common C-terminal portion. Proinsulin antibodies have been prepared in several laboratories and have been used to show that when the disulfide bridges of proinsulin are broken by reduction in urea solution they can be reformed in the proper order in good yield by reoxidation.