Separation by cation-exchange high-performance liquid chromatography of three forms of Chinese hamster ovary...

Purified recombinant (r) interleukin 2 (IL-2) produced by a transformed Chinese hamster ovary cell line shows a single peak when analysed by reversed-phase high-performance liquid chromatography, but it can be resolved into three forms by sodium dodecyl sulphate polyacrylamide gel electrophoresis. These three forms were successfully isolated by narrow-bore ion-exchange chromatography through optimization of the elution conditions. The addition of n-propanol as an organic modifier to the mobile phase proved to be essential for the recovery of the protein from the column in a yield of 90% or better based on protein quantification and biological activity determination. This chromatographic method was used for the purification of these three rIL-2 forms which represent variable glycosylation of a single polypeptide chain. A comparison of the biological activities using the murine CTLL-2 cell proliferation assay showed that the specific activities of the three forms are similar.