title: Separation of recombinant human interleukin-2 and methionyl interleukin-2 produced in Escherichia coli.
abstract: Escherichia coli harboring the gene coding for human interleukin-2 (IL-2) produced methionyl IL-2 (Met-IL-2) having an additional methionine residue at the amino terminus as well as IL-2 starting with the amino terminal alanine. IL-2 and Met-IL-2 were copurified from a cell-free extract. It was difficult to separate these two molecular species from each other because of the similarities of their physico-chemical characteristics. We found that the isoelectric points of IL-2 and Met-IL-2 were slightly but significantly different and succeeded in separating these two molecular species by utilizing the difference of their isoelectric points. The isoelectric points of IL-2 and Met-IL-2 thus obtained were determined to be 7.7 and 7.5, respectively. The in vitro specific activities of these two species were the same and similar to that of natural human IL-2 derived from peripheral blood lymphocytes.
mesh_terms: D000595:Amino Acid Sequence; D006801:Humans; D007376:Interleukin-2 / Q000031:analogs & derivatives / Q000302:isolation & purification*; D007526:Isoelectric Point; D008715:Methionine; D011994:Recombinant Proteins / Q000302:isolation & purification*
chemical_list: D007376:Interleukin-2; D011994:Recombinant Proteins; D008715:Methionine