Protein L Magnetic Beads 

Protein L Magnetic Beads contain a recombinant Protein L that binds to antibody species and subtypes with appropriate Kappa light chains, while Lambda light chains and some Kappa light chains do not bind. During IP, less magnetic beads are needed, non-specific binding is low, enabling Protein L magnetic beads to be used in IP conveniently and efficiently.

4°C, 2 years.

Do not centrifuge, dry or freeze the magnetic beads.

1. Preparation of Magnetic Beads

1.1 Resuspend the Magnetic Beads in the vial (tilt and rotate for 2 minutes or gently pipette for 10 times).

1.2 Transfer 25-50 μL of Protein L Magnetic Beads into a 1.5 mL tube (Transfer amount may be adjusted as required).

1.3 Add 400 μL of binding/wash buffer to the beads and gently pipette to mix. Place the tube into a magnetic stand to collect the beads against the side of the tube (Hereinafter referred to as magnetic separation). Remove and discard the supernatant. Repeat this step for 2 times.

2. Binding of Antibody

2.1 Dilute antibody (Ab) to the final concentration of 5-50 μg/mL with binding/wash buffer. The optimal amount of Ab may be adjusted as required.

2.2 Add 400 μL of diluted Ab to the Protein L Magnetic Beads. Rotate tube for 30 minutes at room temperature or 2 hours at 4°C.

2.3 Perform magnetic separation. Transfer the supernatant into a new tube for further analysis, if desired. The supernatant is the non-binding fraction.

2.4 Add 400 μL of binding/wash buffer to the beads and gently pipette to mix. Place the tube into a magnetic stand to collect the beads against the side of the tube. Remove and discard the supernatant. Repeat this step for 4 times.

3. Immunoprecipitation of Target Antigen

3.1 Remove the tubes from the magnetic separator and add your sample containing the antigen (Ag) (typically 5-50 μg in 400 μL binding/wash buffer) and gently pipette to resuspend the Protein L Magnetic Beads-Ab complex.

3.2 Incubate with rotation for 30 minutes at room temperature or 2 hours at 4°C to allow Ag to bind to the Protein L Magnetic Beads-Ab complex.

3.3 Perform magnetic separation. Remove and discard the supernatant.

3.4 Wash the Magbeads-Ab-Ag complex 5 times using 400 μL binding/wash buffer for each wash. Perform magnetic separation between each wash, remove supernatant and resuspend by gentle pipetting.

3.5 Resuspend the Protein L Magnetic Beads-Ab-Ag complex in 400 μL binding/wash buffer and transfer the bead suspension into a clean tube. This is recommended to avoid co-elution of the proteins bound to the tube wall.

4. Elution

This is a non-denaturation elution method.

4.1 Perform magnetic separation and remove the supernatant. Add 400 μL of binding/wash buffer into the tube and rotate for 5 minutes. Perform magnetic separation for 1 minute and remove the supernatant. Then add 25-50 μL elution buffer into the tube with magnetic beads-Ab-Ag complex, rotate for 5 minutes.

4.2 Perform magnetic separation, collect the supernatant.

4.3 The final solution can be used as samples for denaturing SDS-PAGE. Or the elution can be adjusted to neutral pH with neutralization buffer immediately and used for further analysis.