What should I do if I get low binding to Dynabeads Protein A or Protein G magnetic beads?
Here are a few suggestions to try if you are getting low binding to the Dynabeads protein A/G beads:
-Verify the binding/specificity of your antibody to your antigen, e.g., by ELISA
-Check the binding of your antibodies to the beads; if the antibodies are not captured and bound to the beads, the immunoprecipitation experiment will not work
-If you have used the indirect IP method, try the direct IP method; conversely, if you have used the direct IP method, try the indirect IP method
-Check the amount of beads and sample volume with respect to the capacity of the different beads provided in the package inserts, and increase the amount of beads or the concentration of your antibody during coupling
-Increase the incubation time
-If using a commercially sourced antibody, confirm it is validated for IP
-Try another antibody
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
What should I do when the antibodies coupled to Dynabeads Protein A or Protein G magnetic beads have lost function after crosslinking?
Here are a few suggestions you can try:
-Perform the IP without crosslinking the antibody to the beads
-Reduce the amount of crosslinker used to covalently attach the antibody to the beads
-Try a different crosslinker
-To prevent co-elution of antibody, try one of our surface-activated Dynabeads magnetic beads; this allows you to conjugate the antibody to the beads directly, through covalent binding
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
What should I do if Protein G is coming off the Dynabeads Protein G magnetic beads?
Here are some suggestions:
-Wash the beads prior to use in 100 mM glycine at a pH of 11.3 followed by a wash with 200 mM glycine at a pH of 2.8 for a very short period. Immediately transfer the beads to PBS with 0.01% Tween-20.
-Perform the elution in the low pH, glycine-based elution buffer recommended in the manual.
-Crosslinking of the antibody to the Protein G also crosslinks the Protein G to itself, which anchors it to the bead surface.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
How can I reduce background using Dynabeads Protein A or Protein G magnetic beads?
Protein G is coated onto hydrophilic beads. If your background is protein-mediated, then we normally suggest having a combination of blocking protein and non-ionic detergent both in the coupling and washing buffer to reduce nonspecific binding
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
I was able to immunoprecipitate my protein using Dynabeads magnetic beads before, but after crosslinking the antibody to the beads I get no protein bands on my gel. What could be the problem?
The binding sites of your antibody have likely been altered by the crosslinking. When this occurs, your antibody will show reduced affinity or no affinity to its target antigen. Another consequence of crosslinking can also be increased affinity for unintended (nonspecific) targets. This is always a high risk with crosslinking, and it is a problem easily avoided by choosing another path to covalent antibody coupling. You can try using the Dynabeads Antibody Coupling Kit. This kit is a far superior solution for covalent antibody coupling to Dynabeads magnetic beads (compared to crosslinking with Dynabeads Protein A or G magnetic beads). The Dynabeads Antibody Coupling Kit is compatible with almost any antibody. It is designed specifically for covalent antibody coupling to Dynabeads magnetic beads. Unlike crosslinking, the Dynabeads Antibody Coupling Kit will not alter antibody specificity or affinity.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.