N-terminal amino acid analysis of growth hormones from human, monkey, whale, and beef pituitary glands.

The isolation of growth hormone (somatotropin) from human, monkey, and whale pituitary glands has recently been reported (l-3). Preliminary studies on the hormone proteins from these species have suggested that phenylalanine is their sole N-terminal amino acid residue (l-3), in contrast to the two N-terminal residues, alanine and phenylalanine, which have been reported for the bovine somatotropin (4, 5). In this paper are reported the results of an investigation designed to confirm the findings of earlier N-terminal studies on human, monkey (rhesus, Macaca mulatta), and whale (humpback) growth hormones, and to elucidate a partial N-terminal amino acid sequence for the somatotropins from these three species and for the bovine hormone as well.