Hi there
I am trialling a purification of OPN (osteopontin) from a bone lysate using anti-OPN bound protG seph.
My problem is that elution in 100mM glycine, 500mM NaCl elutes both the protein and the antibody from the column and neutralisation of the elutant allows rebinding of OPN to anti-OPN.
Any ideas on how to separate protein from antibody either on column or after elution without gel-purification from PAGE gel?

Cheers