Purification and Properties of Reptilian and Amphibian Growth Hormones1

Abstract

Highly purified growth hormone was isolated from the pituitaries of 2 reptilian species, the snapping turtle [Chelydra serpentina] and the sea turtle [Chelonia mydas] and 2 amphibian species, the bullfrog [Rana catesbeiana] and the leopard frog [R. pipiens]. 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 [elution volume/void volume] 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 4 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. Many elements of growth hormone structure were probably strongly conserved during evolution.