Studies on the serial extraction of pituitary proteins.

Abstract

Pituitary glands of beef, sheep and pig origin were successively extracted with water at pH 5.5, M/10 (NH4)2SO4 at pH 4.0, M/4 (NH4)2SO4 at cither pH 5.5 or 7.5, and finally with 60 percent ethanol at pH 9.8 to 10. The extracts were bioassayed for the anterior pituitary hormones and for the proteinases I and II. With certain exceptions, the first extract contained mainly FSH and proteinase I; the second, LH and TSH, the third, GH and proteinase II; and the fourth, prolactin. FSH and GH were further purified to establish the amenability of these extracts to fractionation. Growth hormone isolated from beef pituitary extracts prepared at pH 5.5 appears to be a mixture of two biologically active proteins: one with alanyl and phenylalanyl NH2-terminal groups and another with methionyl and alanyl NH2-terminal groups. Small amounts of NH2-terminal serine and glutamic acid were also present. By varying the conditions of extraction appropriately, the amounts of the two types of hormones could be varied inversely. ...