co-immunoprecipitation problem

[bg2z at musicb.mcgill.ca]

I am using a rabbit antibody to immunoprecipitate a protein under 
co-immunoprecipitation conditions, which should, and does bring down a complex 
containing another protein (HA tagged) against which I have a mouse Ab 
(12CA5). The problem I have is that my initial immunoprecipitating rabbit Ab 
is recognized on the nitrocellulose by the secondary Ab I use to detect 12CA5 
(Goat anti mouse HRP- I detect using ECL) and the heavy chain migrates almost 
exactly where the tagged protein is located. I know my protein is there 
because there is always extra signal right above the IgG heavy chain, but it 
would look much nicer if there was a way to degrade, or get rid of 
specifically the IgG heavy chain. Other than running really loose gels (7% and 
less) is there a way to get rid of that fat whopping IgG band? any advice will 
be greatly appreciated

Dino De Angelis, McGill Biochemistry