I face certain problems with the BCA protein assay: I did some (first) testings with BSA standards that worked quite well. Using the same standard assay procedure with IgG also led to nice calibration curves.
Now I want to determine TNF quantities in presence of L-Cystein, which seems to be quite difficult: I´ve been using defined L-Cystein add-ons to the TNF standards but instead of TNF-dependent calibration curves I got more or less a bad extinktion constant.
Additionally my TNF samples show higher extinctions than the described TNF/L-Cystein-calibration standards.
My TNF sample consists of 10mM Na2HPO4/NaH2PO4 buffer, 2mM EDTA, 30mM NaCl, pH6,7 buffer. So far I could not find any literature saying that one of these substances interfere with the BCA Protein Assay.
Does anybody have a clue how to solve one of my problems?
Edited by Kataya, 29 June 2009 - 01:17 AM.