Isolation and characterization of luteinizing hormone from amphibian (Rana catesbeiana) pituitaries.

We report here the first isolation of an anterior pituitary hormone from an amphibian species, the bullfrog ($\text{Rana catesbeiana}$). Highly purified luteinizing hormone was isolated from alkaline extracts of bullfrog pituitaries by salt fractionation, chromatography on ion-exchangers and gel filtration. Characterization studies show the hormone to contain 9% carbohydrate and to possess an amino acid composition similar to ovine luteinizing hormone. Sedimentation-velocity experiments in the ultracentrifuge indicate that the bullfrog gonadotropin dissociates in acidic solution and is composed of subunits. Bullfrog luteinizing hormone is highly active in an $\text{in vitro}$ toad ovulation assay and also ellicits testosterone production $\text{in vitro}$ from isolated rat testis Leydig cells.