Proteins in sample buffer - Interference with protein assays (Oct/27/2004 )

I have isolated proteins of HEPG2 cells in sample buffer and now I want to determine the amount of protein I have collected.
I have used a Bradford and a Lowry assay, but they give very different results.
My question now is, is it possible to do a protein quantitation assay when the protein is in sample buffer, and if so whitch assay?

Thanks for replying

Hi, Jeroen.

You can do the protein quantitation in that conditions with both of methods with an important consideration: check the detergent concentration in your sample buffer is compatible with the reagents used for the quantitation assay. This is because detergents can alter the spec readings. The quantitation reagents from a kit or package are calibrated with several substances for giving reliable results (check in the manual), but if the detergent concentration in your sample is over the compatibility range you can get weird results. If your sample buffer have too much detergent (or anything else that could alter the absorbance readings) you can dilute the protein sample until the detergent concentration get in the compatibility range.

Good luck.