Did you resuspend the insoluble precipitate and run on SDS PAGE? The precipitate is not your target protein, then it might be host proteins co-purified with your target Ab.

Some times affinity chromatography can bind non targeted proteins. These proteins may co-purify with the target protein. That's could be the reason you did not see any reduction in antibody concentration even after the centrifugation.

hi

iam agree with Amal Senevirathne

good luck

Hi all, thanks for the reply.

Although it was difficult to resuspend the precipitate, I still tried it on SDS-PAGE and it wasn't my target protein for sure.

I only got the precipitation during the concentration of some specific recombinant IgGs, but since they aren't my target protein, what is the cause of this?

If the precipitate is not your target protein, and your target protein remains in solution upon concentration, you will not worry about it. It is a good thing to remove co-purified contaminants by centrifugation. However, you may have contaminant proteins in solution with your target proteins. I am not sure the impact of the contaminant protein in solutions. The purity of your target protein often depends on its intended use. Do you need high purity of your proteins? If the presence of contaminant proteins do not affect the downstream procedures/biological activities, I will not worry about the presence of trace amount of the contaminants.

Hi Alemu, I will use the antibody for animal injection, so high purity is preferred. But at this point it seems like letting precipitate, rather than adding high salt and preventing aggregation, is a better way to eliminate the contaminated products and increase the purity?