Factors That Affect the Fragmentation of Growth Hormone and Prolactin by Hypophysial Proteinases.

Ellis et al. (l), Li and Papkoff (2) and Ellis (3) have reported changes in biological activity and electrophoretic behavior after treatment of growth hormone with acidic and alkaline buffers, and Lazo-Wasem and Graham (4) have studied the stability of growth hormone prepared by different procedures. Recently, it has been shown (5) that highly purified preparations of growth hormone are contaminated with proteinases. The study reported here concerns the various factors that influence the action of these enzymes and data are presented that show that many of the observations made on the stability of growth hormone can be explained by the presence of proteolytic enzymes in samples of the hormone.