Further Studies on the Chemical Nature of Reptilian Gonadotropins: FSH and LH in the American Alligator and Green Sea Turtle

Fractionation of pituitaries from the American alligator (Alligator mississipiensis) and the green sea turtle (Chelonia mydas) revealed the existence of two distinct types of gonadotropins in each of these reptiles. The behavior of these hormones in three chromatographic systems (Amberlite CG-50, sulfoethyl-Sephadex C-50 and DEAE-cellulose) and their activities in several nonmammalian bioasays paralleled those of FSH and LH from other tetrapod species. The hormones from each reptile were prepared in highly purified form for chemical analysis. Results of gel filtration on Sephadex G-100 indicated two distinct forms of FSH in each reptile, but other chemical and biological data revealed little differences between these two forms. In general, chemical characterization (N-terminal amino acids, amino acid composition and carbohydrate content) revealed a marked similarity among the FSHs and LHs of the various reptiles, birds and mammals studied thus far. For example, variations in LH composition between classes is not greater than within classes or orders. The action of neuraminidase on the reptilian gonadotropins suggested that the loss of sialic acid does not correlate well with biological activity.