Optimization of magnetic bead-based protein purification
5 % suspension
|Binding capacity||32.4 mg/ml (1.2 pmol/µl of a 27 kDa protein)|
|Matrix||6% agarose, crosslinked, spherical magnetic beads|
|Bead diameter||20-40 µm (30 µm average)|
|Specificity||Strep-tag®II and Twin-Strep-tag®|
In the protocol and the following information on optimization of magnetic bead purification, “bead volume” refers to the total volume of beads. 20 µl of the 5 % suspension contain 1 µl of beads.
IBA’s protocol for MagStrep Strep-Tactin®XT beads describe the basic steps for magnetic bead protein purification. Depending on factors such as target protein concentration or size, it may be possible to increase the yield by adjusting parameters of IBA’s base protocol like bead volume or incubation time.
The more beads are used, the more target protein can be bound in a short time.
An increase of the incubation time for several minutes can increase the amount of bound protein and consequently the protein yield.
In comparison to small proteins, large proteins need more space to bind whereby binding sites on the beads are not accessible for other proteins. Thus, purifying large proteins requires more beads to purify an equal number of proteins as for small proteins.
In high concentrated samples, protein and bead can quickly find each other. This facilitates the purification of as much protein as possible.