Ion exchange chromatography of glucagon in ureacontaining buffers.

Although the existence of the pancreatic hyperglycemic factor was postulated by Kimball and Murlin (1) in 1923, it was only recently that glucagon was isolated in crystalline form by Staub et al. (2). Glucagon was shown to be a basic polypeptide at that time. Such a peptide would be expected to yield successfully to chromatography on the carboxylic ion exchange resin Amberlite IRC-50, except for the fact that the hormone is insoluble in aqueous buffers in the region of pH 6. Glucagon is soluble, however, in this region of pH if urea is present, and may thus be used as an example of a special application of chromatography in urea-containing buffers (3) to peptides and proteins with similar solubility characteristics. Furthermore, it was of interest to apply chromatography to glucagon with the use of a buffer system similar to that used for insulin (3) to determine whether or not glucagon could be detected in the chromatograms of insulin.