Zone electrophoresis of hypophyseal growth hormone (somatotropin) on starch.

Growth hormone preparations were obtained by methods previously described (1, 3) from the anterior lobes of ox pituitary glands. The biological activity of these preparations was estimated by the tibia test (5) in hypophysectomized rats. Electrophoretic experiments were carried out in a cold room at 3”. The technique of zone electrophoresis is a modification of the method of Kunkel and Slater (6). Semicylindrical glass troughs’ were used as containers for the immobilized medium; these are made by cutting 40 or 60 cm. lengths of Pyrex tubing, 4 cm. inner diameter, in half longitudinally. The trough is filled with a viscid mixture of starch and buffer; the excess buffer is removed by pressing a triple layer of filter paper against the surface. Both ends of the trough are then covered with a double layer of filter paper cut in strips 15 cm. long, in order to insure contact between the starch block and the buffer solution in the electrode vessels. The top of the trough is covered first with a strip of Parafilm and then with a glass plate cut to size, held in place by means of rubber bands. The electrode vessels are similar to those described by Kunkel and Tiselius (7). After the trough has been left for at least 4 hours for equilibration with