FIG. 1.

Characterization and quantification of rmSEB. Recombinant mutant SEB (rmSEB) was expressed in E. coli and purified as a C-terminal six-histidine-tagged fusion protein. (A) A Coomassie blue-stained SDS-PAGE gel of 1, 2, and 5 μg of purified rmSEB showed a single band migrating at approximately 28 kDa compared to the total E. coli protein lysate (lane L). Migration of protein standards are shown to the right of the gel. (B) Western blot analyses demonstrated that rmSEB (rm) could be recognized by the same antibodies used to detect native SEB (n). Note that rmSEB migrates at a slightly higher molecular weight due to the amino acid additions made to this recombinant protein. (C) Known quantities of standard proteins (bovine albumin, egg albumin, and lysozyme) were coelectrophoresed on a Coomassie blue-stained SDS-PAGE gel to quantify the amounts of rmSEB used in these studies.