Attracting streptavidin magnetic beads with the 8/9 setup doesn't seem to work well: attraction to the side makes it difficult to discern a difference between setups. Orienting the magnet vertically seems a little more promising since it is the strength of the magnet directly against gravity; hopefully the gradients of magnetic particles will differ based on differing properties of large aggregates (densities, magnetic bead: thrombin bead ratio, surface area (and friction) differ. The vertical setup yields very little pulling power even for .2 mL PCR tubes, so I cut a couple up to get the magnet in range. This experiment is questionable as I reused the refrigerated 8/10 experiment beads (incubating on a rocker for 30 minutes).
I also reran streptavidin plus the various types of thrombin we've used and BSA on a SDS-PAGE 12% Tris-Glycine gel for 1.5 hours. Results shown below.
|1||Seeblue plus2 ladder|
|2||8 uL 1% BSA|
|3||40 pmol Haematologic Technonlogies human alpha thrombin|
|4||40 pmol Sigma Human thrombin|
|5||40 pmol Bovine Thrombin w/o BSA|
|6||90 pmol streptavidin|