I was wondering if anyone knows an assay or an easy way in order to check the redox state of a protein that is secreted by the cells in the culture media?
HI Mina, If you have an antibody to your protein of interest you could percipitate your proteins from the media and do a redox blot using the MM(PEG) or something similar to react with your free thiols, the following article gives a number of options http://www.sciencedirect.com/science/article/pii/S2213231714000779?via%3Dihub . If you have access to a mass spectrometer you could also try to analyse the redox state of the protein this way. Hope this helps, Brian