Purification and properties of reptilian and amphibian growth hormones

Highly purified growth hormone was isolated from the pituitaries of two reptilian species, the snapping turtle and the sea turtle, and two amphibian species, the bullfrog and the leopard frog. Characterization studies were performed with these growth hormones in comparison with mammalian and avian growth hormones. Great similarities among these species were found in chromatographic behavior, Ve/Vo ratios (2.0) on gel filtration, disc electrophoretic patterns, terminal amino acid residues and immunochemical reactivity with snapping turtle growth hormone antiserum. Species differences were noted in amino acid composition and immunoactivity measured by rat growth hormone antiserum, and these appeared to reflect the phylogenetic relationships among the four tetrapod species. The turtle and frog growth hormones gave parallel dose responses in the rat tibia assay. All were less potent than the bovine growth hormone standard except the bullfrog growth hormone which was equipotent if not more active. The data indicate that many elements of growth hormone structure have been strongly conserved during evolution.