A Rapid Means of Separating A₁₄-¹²⁵I-Insulin from Heterogeneously Labeled Insulin Molecules for Biologic Studies

We have used two methods for the preparation of a highly homogeneous insulin with high specific activity. After iodination with chloramine T, the labeled peptides were retained on a disposable Sep Pak cartridge and subsequently eluted. The eluted labeled insulins were further purified by either DEAE cellulose or high performance liquid chromatography (HPLC) to separate A₁₄-¹²⁵I- from A₁₉-¹²⁵I-insulin. Both methods of chromatography were effective, but HPLC offered the advantage of better resolution in less time and higher yields of A₁₄-¹²⁵I-insulin, which is suitable for biologic studies in various target tissues.