APT^SEB1 binds to SEB, but not BSA.

<p>Aptamer-precipitation of SEB from 10-fold excess of BSA using several DNA sequences was visualized by 4–12% SDS-PAGE with silver stain. Dynabeads® M-270 Streptavidin magnetic beads coated with APT^SEB1 (lane 3), random 78-base ssDNA (lanes 4–6), PCR forward primer (used in this study, lane 7), and nothing (lane 8), were incubated in 500 µl PBS-T incurred with 10 µg BSA and 1 µg SEB. After washing the Dynabeads with PBS-T, the protein eluate (lanes 3–8) was loaded onto the SDS-PAGE gel. Lanes 1 and 2 contain 50 ng of standard BSA and SEB, respectively. The protein bands labeled as “SA” represent the monomer of streptavidin liberated by the elution protocol.