[Amino acid sequence of seiwhale somatotropin]

Thirteen homogenous peptides were isolated from the chymotryptic hydrolysate of seiwhale somatotropin. The amino acid composition and sequence of the chymotryptic peptides were determined. Two large peptides were isolated from the tryptic hydrolysate of the performic acid-oxidized somatotropin. One of them had 20 amino acid residues and contained cysteic acid; the other one consisted of 31 residues and contained tryptophane and numerous leucine residues. The amino acid sequence of tryptic peptides was established after their hydrolysis with chymotrypsin. Based on these and earlier published data a complete amino acid sequence of seiwhale somatotropin comprising 190 amino acid residues was proposed. O comparison of primary structure of somatotropins from 6 different sources revealed the most conservative and variable regions of the hormone polypeptide chain.