Sedimentation, diffusion, and molecular weight of crystalline pituitary growth hormone.

The recent work of Fishman, Wilhelmi, and Russell (1,2) has made available a crystalline growth hormone isolated from the bovine anterior pituitary gland. It was of considerable interest to determine the sedimentation behavior of this protein in the ultracentrifuge and, at the same time, to obtain the molecular weight by this method. The amorphous preparation of Li, Evans, and Simpson (3) has not been studied in the ultracentrifuge, although estimations of the molecular weight have been obtained by other methods (3-5). The lyophilized samples of the crystalline growth hormone were prepared as already described (2). The material was electrophoretically homogeneous at pH 4.0 and at pH 10.0. When the hormone was injected daily for 10 days into hypophysectomized male rats weighing 100 gm., it produced, at a daily dose of 20 Y, an average increase in body weight of 15.8 gm. and, at a daily dose of 100 Y, an increase in body weight of 25.0 gm. The corresponding increments in the width of the proximal epiphyseal cartilage of the tibia were 180 p and 207 p.