Schematic figure and features describing the three different scFv magnetic bead coupling strategies; epoxy, streptavidin and anti-FLAG.

The epoxy format is different to the other two in that scFv are coupled directly to the magnetic beads through a covalent coupling to any lysine residue on the scFv. This results in randomly oriented (non-oriented) scFv on the beads. As opposed to the streptavidin-coated beads and M2 anti-FLAG beads where the scFv is immobilized through coupling to the bead surface through a linker at the back-end of the scFv and thus an oriented coupling that is not interfering with the binding site of the scFv. The steptavidin and anti-FLAG formats also require much less scFv and shorter coupling time.