title: Oxidation of methionine residues of recombinant human interleukin 2 in aqueous solutions.
abstract: When recombinant human interleukin 2 (rIL-2) was stored for a long period in aqueous solutions, its methionine residues were spontaneously oxidized to the corresponding methionine sulfoxides. To clarify the oxidation process, rIL-2 was treated with hydrogen peroxide, and three oxidation products were separated by reversed-phase high-performance liquid chromatography. By means of amino acid analyses after cyanogen bromide cleavage of these products, we found that Met104, Met23, and Met39 were consecutively oxidized in this order; Met46 was not oxidized easily. The substances generated by extended storage of rIL-2 in aqueous solutions were identified by comparison of their peptide maps with those of the chemically oxidized products. The protein-chemical properties of these products, except for the modifications of the methionine residues, were similar to those of intact rIL-2; their biological activities were almost the same.
authors.forename: K
authors.initials: K
authors.lastname: Sasaoki
authors.forename: T
authors.initials: T
authors.lastname: Hiroshima
authors.forename: S
authors.initials: S
authors.lastname: Kusumoto
authors.forename: K
authors.initials: K
authors.lastname: Nishi
mesh_terms: D006801:Humans; D007376:Interleukin-2 / Q000032:analysis*; D008715:Methionine / Q000032:analysis*; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000032:analysis; D012996:Solutions
chemical_list: D007376:Interleukin-2; D011994:Recombinant Proteins; D012996:Solutions; D008715:Methionine