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IP no target protein in elution - (Mar/03/2011 )

Hi, I'm new in immunoprecipitation and just did one trial with Protein G Sepharose (Sigma), however I didn't see any target protein in my elution. What's wrong?
I used 20mM sodium phosphate (pH7.0) as my washing buffer, and 0.1M glycine-HCl (pH2.7) as eluting buffer. I'm using Anti-c-Myc (Sigma) as my AB, but not sure of how much should I use, so I added 2ul undiluted AB into 20ul resin. Does all this seem right? Thank you for help...



For magnetic beads 1-10µg Abs per 50µl beads.

A few suggestions
<*>Verify binding/specificity of your antibody to your antigen, e.g., by ELISA.
<*>Check the binding of Abs to the beads. If the Abs are not captured and bound to the beads,
<*>If you have used the indirect method, try the direct method. Conversely, if you have used the direct method, try the indirect method.
<*>Check the amount of beads and sample volume. increase the amount of beads or the concentration of your antibody during coupling.
<*>Increase the incubation time.
<*>Try another antibody.

Ketil Winther Pedersen, Ph.D
Head of Technical support for Dynabeads products
Tel: +47 22 06 11 10 (direct)
Fax: +47 22 51 95 05