Protease inhibitor in wash step? - (Sep/10/2013 )
Have you guys ever tried not adding any protease inhibitor or much lower concentrations in the wash buffer for CoIPs? Theoretically, after incubation with the beads, most of the proteases should be washed off.
I never add the PI at that step, just because I will be denaturing it at 95c within 30mins. I have never had any issues.
Adding PI to the wash buffer following bead pulldown seems kind of excessive. I would try them side by side and determine if the results change. At least this way if anyone higher up has a problem with it, you have evidence supporting you.